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Contents
1. SummaryMeasuresofPopulationHealth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Overview of the Role of Summary Measures in Health. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 The process of population health change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2.2 Past use of summary measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3PotentialSummaryMeasuresSuggestedforHealthyPeople2010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.4 Availability of Data for Estimating the Proposed Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2. MethodsforCalculatingHealthyLifeExpectancy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.2 The Life Table Technique. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1 Estimating the average expectation of life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.2.2 Estimating healthy life expectancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.2.3 Standard errors of healthy life expectancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113. ExpectedYearsofHealthyLifeUnderVariousDefinitionsofHealth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133.2 Expected Years of Healthy Life for Males and Females. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2.1 Expected years in good or better health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133.2.2 Expected years without activity limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143.2.3 Expected years without work limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153.2.4 Expected years without functional dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153.2.5 Expected years without diseases or chronic conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.2.6Expectedyearswithbodymass index(BMI) less than25andyearswithBMI lessthan30 . . . . . . . . . 18
3.3 Expected Years of Healthy Life for the White and Black Populations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.3.1Expectedyearsingoodorbetterhealthfor thewhiteandblackpopulations . . . . . . . . . . . . . . . . . . . . . . 203.3.2Expectedyearswithoutanyactivitylimitationforthewhiteandblackpopulations. . . . . . . . . . . . . . . . . 213.3.3ExpectedyearswithoutADLorIADLlimitationforthewhiteandblackpopulations. . . . . . . . . . . . . . . 223.3.4 Expected years with BMI less than 30 for the white and black populations . . . . . . . . . . . . . . . . . . . . . . 22
3.4 Comparison of Results from the Various Measures of Health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243.4.1 Comparison across measures at 30 and 65 years of age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.4.2 Comparison across measures for males and females at 65 years of age. . . . . . . . . . . . . . . . . . . . . . . . . . . 253.4.3Comparisonacrossmeasuresforthewhiteandblackpopulationsat65yearsofage . . . . . . . . . . . . . . . 273.4.4 Comparison across measures by age, sex, and race . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
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4. TrendsinLifeFreeofActivityLimitation:UnitedStates,198595. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424.2Age-AdjustedDeathandActivityLimitationRates:UnitedStates,198595. . . . . . . . . . . . . . . . . . . . . . . . . . . 424.3Age-SpecificDeathandActivityLimitationRates:UnitedStates,1985and1995 . . . . . . . . . . . . . . . . . . . . . . 434.4 Years Free of Activity Limitation: United States, 198595 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444.5GainsinLifeExpectancyandExpectedLimitation-FreeYears:UnitedStates,198595. . . . . . . . . . . . . . . . . . 454.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5. TheImpactofIncompleteDataonHealthyLifeExpectancyEstimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525.2The1995NoninstitutionalizedCivilianandInstitutionalizedPopulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.2.1 The noninstitutionalized civilian population. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 545.2.2 The 1995 nursing home population. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.3 Functional Limitation: The Community and Nursing Home Populations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 545.3.1 Functional limitation: The population 5 years of age and over. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555.3.2 Functional limitation: The population 65 years of age and over . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.4 Effect on Healthy Life Expectancy Estimates for the Older Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586. SummaryandConclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Figures1.1 Population health change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Potential health changes for individuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.3 Health care and public health intervention opportunities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.1 A schematic presentation of the model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.2 Aschematicframeworkforestimatinghealthylifeexpectancyat thenationallevelusingrespondent
assessed health status as an example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.3 Example of attributes for health classification system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.1 Percentageofpersonsreportinggoodorbetterhealth,byageandsex:UnitedStates,1995 . . . . . . . . . . . . . . . 143.2 Percentageofexpected lifeingoodorbetterhealthatbirth,20,and65yearsofage,bysex:
United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143.3 Percentage free of activity limitation, by age and sex: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153.4 Percentageof lifeexpectancyfreeofanyactivity limitationatbirth,20,and65yearsofage,bysex:
United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163.5 Percentageabletoperformpersonalcareneedsornot limited inotherroutineneeds,byageandsex:
United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163.6 Percentageof lifeexpectancyable toperformpersonalcareneedsornotlimitedinotherroutineneeds at 45, 65, and 75 years of age, by sex: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.7 Percentageof lifeexpectancyfreeofchronicarthritisat30,65,and75yearsofage,bysex:
United States, 199496 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.8 Percentageof lifeexpectancyfreeofchronicheartdiseasesat30,65,and75yearsofage,bysex:
United States, 199496 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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3.9 Percentageof lifeexpectancyfreeofchronichypertensionat30,65,and75yearsofage,bysex:United States, 199496 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.10 Percentage not obese, by age and sex: United States, 199496 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.11 Percentage in good or better health, by age and race: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.12 Percentagefreeofanytypeofactivitylimitation,byageandrace:UnitedStates,1995 . . . . . . . . . . . . . . . . . . 223.13 Percentageabletoperformpersonalcareneedsornot limited inotherroutine
needs, by age and race: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.14 Percentage not obese, by age and race: United States, 199496 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.15 Lifeexpectancyandexpectedyearsofhealthylifeunderdifferentdefinitionsofhealthat30yearsof
age, both sexes: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243.16 Lifeexpectancyandexpectedyearsofhealthylifeunderdifferentdefinitionsofhealthat65yearsof
age, both sexes: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.17 Lifeexpectancyandexpectedyearsofhealthylifeformalesunderdifferentdefinitionsofhealthat
65 years of age: United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.18 Lifeexpectancyandexpectedyearsofhealthylifeforfemalesunderdifferentdefinitionsofhealthat
65 years of age: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.19 Lifeexpectancyandexpectedyearsofhealthylifefor thewhitepopulationunderdifferentdefinitionsof
health at 65 years of age: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.20 Lifeexpectancyandexpectedyearsofhealthylifefor theblackpopulationunderdifferentdefinitionsof
health at 65 years of age: United States, 1995
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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3.21 Sexdisparities inhealthundervariousdefinitionsofhealthstatus,byage:UnitedStates,1995 . . . . . . . . . . . 283.22 Racialdisparitiesinhealthbetweenwhiteandblackpopulationsundervariousdefinitionsofhealthstatus,
by age: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294.1 Number of deaths per 1,000 for white males, by age: United States, 1985 and 1995 . . . . . . . . . . . . . . . . . . . . . 434.2 Numberofdeathsper1,000forwhitefemales,byage:UnitedStates,1985and1995 . . . . . . . . . . . . . . . . . . . 434.3 Number of deaths per 1,000 for black males, by age: United States, 1985 and 1995 . . . . . . . . . . . . . . . . . . . . . 444.4 Numberofdeathsper1,000forblackfemales,byage:UnitedStates,1985and1995 . . . . . . . . . . . . . . . . . . . 444.5 Percentageofwhitemaleswithactivitylimitationfromanycause,byage:UnitedStates,1985
and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444.6 Percentageofwhitefemaleswithactivitylimitationfromanycause,byage:UnitedStates,1985
and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 454.7 Percentageofblackmaleswithactivity limitationfromanycause,byage:UnitedStates,1985
and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 454.8 Percentageofblackfemaleswithactivitylimitationfromanycause,byage:UnitedStates,1985
and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464.9 Expectedyearsfreeofactivitylimitationaspercentageoflifeexpectancy,whitemales:UnitedStates,
1985 and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464.10 Expectedyearsfreeofactivitylimitationaspercentageoflifeexpectancy,whitefemales:UnitedStates,
1985 and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464.11 Expectedyearsfreeofactivitylimitationaspercentageoflifeexpectancy,blackmales:UnitedStates,
1985 and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474.12 Expectedyearsfreeofactivitylimitationaspercentageoflifeexpectancy,blackfemales:UnitedStates,
1985 and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475.1 Percentageof thefemalepopulation65yearsofageandoverwhoneedhelpwithat leastoneactivityof
daily living, by age and residence: United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 545.2 Percentageof thefemalepopulation65yearsofageandoverwhoneedhelpwithat leastone
instrumentalactivityofdaily living,byageandresidence:UnitedStates,1995 . . . . . . . . . . . . . . . . . . . . . . . . 555.3 Percentageof thefemalepopulation65yearsofageandoverwhoneedhelpwithat leastoneactivity
of daily living, by age and residence: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565.4 Percentageof thefemalepopulation65yearsofageandoverwhoneedhelpwithat leastoneactivity
ofdailylivingorinstrumentalactivityofdaily living,byageandresidence:UnitedStates,1995 . . . . . . . . . . 57
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TextTablesA. Ratesperthousandwithchroniccondition,bytypeofconditionandsexatselectedages:UnitedStates,
199496. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17B. Classificationofoverweightandobesitybybodymass index(BMI):Adults,18yearsofageandover . . . . . 19C. Thecommunityandinstitutionalizedpopulation,bysex:UnitedStates,1990 . . . . . . . . . . . . . . . . . . . . . . . . . . 52D. Percentagedistributionof thenoninstitutionalizedandinstitutionalizedpopulation,bybroadagegroup:
United States, 1990 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53E. Percentagedistributionandsexratioofcommunitydwellersand thenursinghomepopulation,bybroadage
group: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
DetailedTables3.1. Lifeexpectanciesandexpectedyearsingoodorbetterhealthandexcellenthealthforselectedages,
by sex: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.2. Lifeexpectanciesandexpectedyearswithout limitationinactivityforselectedages,bysexandtypeof
activity: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313.3. Lifeexpectanciesandexpectedyearswithoutworklimitationforselectedages,bysex:
United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323.4. Lifeexpectanciesandexpectedyearswithoutfunctionaldependencyforselectedyears,bysex:
United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333.5. Lifeexpectanciesandexpectedyearswithoutchronicarthritisandchronicheartdiseasesforselectedages,
by sex: United States, 199496 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343.6. Lifeexpectanciesandexpectedyearswithoutchronichypertensionandchronicdiabetesforselectedages,
by sex: United States, 199496 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353.7. Lifeexpectanciesandexpectedyearswithbodymass index lessthan25andyearswithbodymass index
less than 30 for selected ages, by sex: United States, 199496. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363.8. Lifeexpectanciesandexpectedyearsingoodorbetterhealthforselectedagesof thewhiteandblack
populations, by sex: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373.9. Lifeexpectanciesandexpectedyearswithoutanytypeofactivitylimitationforselectedagesofthe
white and black populations, by sex: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383.10. Lifeexpectanciesandexpectedyearswithout limitationinpersonalcareorotherroutineneedsfor
selected ages of the white and black populations, by sex: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . 393.11. Lifeexpectanciesandexpectedyearswithbodymass indexlessthan30forselectedagesof thewhite
and black populations, by sex: United States, 199496 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.12. Expectedyearsatage30and65estimatedusingdifferentdefinitionsofhealth,byhealthstatus:
United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.13. Expectedyearsatage65estimatedusingdifferentdefinitionsofhealth,byhealthstatusandsex:
United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413.14. Expectedyearsatage65estimatedusingdifferentdefinitionsofhealth,byhealthstatusandrace:
United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414.1. Age-adjusted death rates for all ages, by race and sex: United States, 198595 . . . . . . . . . . . . . . . . . . . . . . . . . 484.2. Age-adjustedactivity limitationratesfromanycauseforallages,byraceandsex:
United States, 198595. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 484.3. Numberofdeathsfromallcausesfor thewhiteandblackpopulations,bysex:UnitedStates,1985and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.4. Limitationofactivityfromanycauseforthewhiteandblackpopulations,bysex:UnitedStates,1985and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.5. Lifeexpectancyandexpectedyearsfreeofanyactivity limitationformalesatbirth,byrace:United States, 198595. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.6. Lifeexpectancyandexpectedyearsfreeofanyactivity limitationforfemalesatbirth,byrace:UnitedStates,198595. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
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4.7. Lifeexpectancyandexpectedyearsfreeofany limitationatbirth,age20,andage65for thewhiteandblackpopulations, by sex: United States, 1985 and 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.1. Numberandpercentagedistributionofcommunityresidentsbysexandbyrace,according toageatinterview: United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.2. Numberandpercentagedistributionofnursinghomeresidentsbysexandbyrace,accordingtoageatinterview: United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.3. Percentageofpopulationneedinghelpwithatleastoneactivityofdailylivingandneedinghelpwithatleastoneactivityofdailylivingorinstrumentalactivityofdaily living,bybroadagegroup,sex,andplaceof residence: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5.4. Percentageofpopulationneedinghelpwithatleastoneactivityofdailyliving,byage,sex,andplaceof residence: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5.5. Percentageofpopulationneedinghelpwithatleastoneactivityofdailylivingorinstrumentalactivityof daily living, by age, sex, and place of residence: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5.6. Expectedyearsof lifeandhealthyyearsoffemalecommunitydwellersandnursinghomeresidentsatselected ages: United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
6.1. Absoluteandrelativedifferences inmaleandfemalehealthy lifeexpectancyat30and65yearsofage:United States, 1995. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
6.2. Absoluteandrelativedifferences inmaleandfemalehealthy lifeexpectancyfor thewhiteandblackpopulations at 30 and 65 years of age: United States, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
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1. SummaryMeasuresofPopulationHealth1.1 Introduction
Theconceptofhealthexpectancywasintroducedinthe
1960s(1)andfurtherdevelopedin the1970s(24).Inmore
recentyears,bothpolicymakersandmembersofthe
researchcommunityhavebeenincreasinglyinterestedinthe
estimationofhealthylifeexpectancy.Thisinterestarises
fromthefactthatmeasuresofhealthylifeexpectancy
potentiallyoffereasilycomprehensiblemeasuresofboththe
levelof,andchangein,thewell-beingofapopulation.
Becausethesemeasuresincorporatebothmortalityand
morbidity,theyseemhighlyappropriateassummary
measuresofhealthintheolderpopulation,wheretherehas
beenconsiderablemortalitydecline,butwherethereis
concernthattheextensionoflifemaynotbeequivalentto
theextensionofhealthylife.Therelationshipbetweenchangesinmortalityand
morbidityandtherelativelygreaterburdenofmorbidityin
theolderagesgainedinterestin the1980s.Debatecentered
onwhetherthefactorsresponsibleforthereductionsin
mortalitywouldhaveasimilareffectonmorbidity.Some
arguedthatmostoftheyearsoflifethattheelderlygained
duetothedeclineofmortalitywerehealthyyearseither
becausetheincidenceofchronicconditionswasbeing
pushedtothelastfewyearsoflife,thatis,thecompression
ofmorbidity(5,6)orbecausethelossoffunctioningor
disabilityfromchronicconditionshadsloweddown(7).
Othersarguedthat themedicalcareimprovementsthatsaved
liveswerenotaccompaniedbyeitherdiseasepreventionthatwouldmaintainhealthystatesorhealthcarethatwould
delayfunctionalconsequencesofdisease(8).
Healthylifeexpectancyisalsoperceivedasausefultool
forhealthplanningandmakinghealth-relatedpolicy
decisions.Anindicationoftheperceivedusefulnessfor
policymakersoftheconceptofhealthylifeexpectancyis
thefactthatyearsofactivelifearenowincludedamong
nationalandinternationalhealthgoals.Fortheyear2000,
theU.S.goalwas65yearsofactivelifeexpectancyatbirth
forthetotalpopulation(9).Thetwooverarchingnational
healthgoalsidentifiedforHealthyPeople2010areto:+
Increasethequalityandyearsofhealthylifeand+ Eliminatehealthdisparities(10).
Thegoalsandobjectivesoutlinedforthedecadein
HealthyPeoplehavebecomecentraltobothmonitoringthe
Nationshealthandplanninganagendatopromotehealth
andpreventill-health.Monitoringthegoalsandobjectives
fortheyear2010will,inpart,beachievedthroughLeading
HealthIndicators,asmallnumberofmeasuresthataddress
majordeterminantsofhealth.TheseLeadingHealth
Indicatorsprovideawayofunderstandinghealthinthe
future,buttherealsohasbeenaneedtodescribe,ina
summaryway,thecurrenthealthof thepopulation.Somesummarymeasurescombineboththequalityand
quantityoflifetoreflectyearsofhealthandcanbeusedto
monitorprogresstowardthe firstof theoverarchinggoals.
Becausetheyarecomparableacrosspopulationswith
differentagestructures,thesemeasuresalsocanbeuseful
formonitoringprogresstowardthesecondgoalof
eliminatinghealthdisparities.Morespecifically,summary
measuresofpopulationhealthcombineage-specific
schedulesofhealthandmortalitytoderiveglobalmeasures
ofpopulationhealththatreflectbothmortalityand
morbidity;inthisway,expectedyearsoflifecanbedivided
intohealthyandunhealthylife.Theyhavebeenproposedas
themostcomprehensivemeasuresforevaluatingoveralltrendsanddifferencesinpopulationhealth.
Asaninitialeffortinthedevelopmentofsummary
measuresofhealth,theNationalCenterforHealthStatistics
(NCHS),CentersforDiseaseControlandPrevention,
sponsoredaworkshopentitledIdentifyingSummary
MeasuresforHealthyPeople2010onSeptember1718,1998,attheUniversityofMarylandsUniversityCollege
ConferenceCenter.Thepurposeofthisworkshopwasto
identifyasetofsummarymeasuresthatcouldbeusedto
evaluateprogresstowardtheoverallgoalsofHealthyPeople2010.
Thecentralquestionaddressedat thisworkshopwashow
tobestcharacterizetheprocessofhealthchangeanddifferentialsinasetof summarymeasuresthatcouldbe
estimatedreliablyandpotentiallyusedbyFederalandState
governmentstodeterminetrendsaswellasdifferencesin
healthbyage,gender,raceorethnicity,andgeographicarea.
Theobjectivesoftheworkshopwereto:
+ ProvideabriefoverviewoftheroleofsummarymeasuresinHealthyPeople2000/2010, includingreportingrequirementsanddataconstraints;
+ Identifyasetofpotentialsummarymeasuresthatshouldbeconsideredformonitoringprogresstowardthefirst
goalofHealthyPeople2010;+ Specifyabilitytocomputethepotentialmeasureswith
existingdatacollectionsystemsorcost-effective
modificationstoexistingdatathatwouldallowthe
computationofmeasures;and
+ Specifya researchagendaforthenextdecadetoevaluatepotentialsummarymeasures.
Thisreportpresentsthefindingsofresearchthatwas
initiatedinresponsetotheworkshoprecommendations.The
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workfocusesonmethodologicanddataissues.Thereport
providesdefinitionsofconceptsandmethodsforcalculatingthe
recommendedsummarymeasures;evaluatesanumberof
possiblemeasuresofmorbidity;reviewsthetrendsovera
decadeforonemeasureofhealthylifeexpectancy;and
examinestheeffectofcombiningdatafromdifferentsources.
1.2Overviewof theRoleofSummaryMeasures inHealth
Thischaptersummarizesconceptualmaterialabout
healthandmortalitythatisidentified,summarized,
measured,andtrackedwithsummarymeasures.Inorderto
identifytheprospectivesummarymeasuresthatbestmonitor
thequalityandyearsofhealthylife(i.e.,oneofthe
overarchinggoalsofHealthyPeople2010) it isnecessarytofirstclarifythedimensionsofpopulationhealthandshow
howtheyarerelatedtohealthbehaviorsandpotential
interventions.
Mortalityoftenhasbeenusedasabasicindicatorof
health.Lifeexpectancyisthemostfrequentlyusedsummarymeasureofmortalityconditionsbecauseitsummarizes
mortalityratesacrosstheentireagerange. Two
characteristicsoflifeexpectancymakeita valuablemeasure
forportrayingmortalityconditionstoaudiencesthatinclude
thegeneralpublicandpolicymakers.First, itisnotaffected
bypopulationage-structure.Thismeansthatvaluescanbe
comparedfordifferentsubgroupsofthepopulationatone
pointintimeorforthesamegroupsatdifferentpointsin
time.Inaddition,becauselifeexpectancyisexpressedin
yearsoflife,itiseasilyinterpretedbybothpolicymakers
andthepublic.Bothofthesecharacteristicsmakelife
expectancyanessentialtoolformonitoringbothtrendsand
differencesinmortalityforthepopulationandsubgroupsofthepopulation.Consequently,extendingthisstatistical
concepttoincorporatevariousstatesofhealthmaygenerate
acceptableandunderstandablestatistics.
Theextensionofthebasiclifetablemodeltoinclude
measuresofhealthcanbeusedtocreatesummarymeasures
ofpopulationhealththatdivideexpectedlifeintohealthy
andunhealthyyears(11,12).Whenhealthstatusisdominated
bychronicconditionsatolderagesratherthaninfectious
diseasesatyoungerages,itispossibletohavebothlonger
lifeanddeterioratingpopulationhealth(13).Forinstance,if
increasedtreatmentofheartdiseaseresultsinmortality
decline,peoplewill livelongerwiththedisease; this,in
turn,willresultinincreasedheartdiseaseprevalence,
especiallyifnewcasesarenotprevented.Iftheyearsoflife
livedwithheartdiseasecontinuetobecharacterizedby
diminishedfunctioning,overallpopulationhealthwill
deteriorateaslifeexpectancyincreases.
Theassociationbetweenmortalitychangeandhealth
changeisweakenedfurtherbecausemanycausesof
morbidityarenotfatalconditions.Forinstance,osteoarthritis
isamongtheleadingcausesofdisabilityamongolder
people,butitisnotalikelycauseofdeath.Asmortality
fromothercausesdeclines,osteoarthritisprevalencecould
increase.Summarymeasuresthatcombinemortalityand
morbidityattemptto capturetheseaspectsofhealthstatus.
1.2.1TheprocessofpopulationhealthchangeThekeyissueindevelopingsummarymeasuresis
definingandmeasuringhealthandhealthchange.Individual
researchersandinternationalgroupshavedonesignificant
workindefiningthedimensionsofhealthandclarifyingthe
processofpopulationhealthchange(14,15). Aconceptual
outlineofthedimensionsofhealthandtheprocessof
changeinpopulationhealthisshowninfigure1.1(16).Any
orallofthedimensionsofhealthcouldbecapturedin
summarymeasures.
Diseases,conditions,andimpairments(e.g.,heart
disease,arthritis,andvisualimpairment)occurbeforethere
isalossinfunctioningortheabilitytoperformcertain
actions(e.g.,walkingablock,climbinga specificnumberof
stairs,orsittingforanallottedtime).Functioninglosscan
thenresultindisabilityoran inabilitytoperforman
expectedsocialrole,oftendefinedasworkforthe
middle-agedandself-careor independentlivingforanolder
population.Deathistheendoftheprocess.Overtime,
changecanoccurinsomeorallofthesedimensions,thatis,
gettingorlivingwithdiseases,experiencingfunctioningloss,
anddying(17).
Disabilityin thiscontextreferstothesituationinwhich
anindividualsabilitiesorlimitationsaredeterminedbythe
interactionoftheirphysical,mental,orcognitivestatuswith
theenvironmentinwhichtheywouldperformsocialroles.
Thedegreeof limitationordisabilityisdependentonhow
Figure1.1.PopulationhealthchangeSOURCE:VerbruggeandJette. TheDisablementProcess.SocialSciencesandMedicine,1994.
2 SummaryMeasuresofPopulationHealth
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wellthepersonalenvironmentaccommodatesthelossin
functioning.Thisdefinitionisequivalenttothatdevelopedin
theInstituteofMedicalModel(18)andsimilartothe
participationdimensionoftheInternationalClassificationof
Functioning,DisabilityandHealth.Inothercontexts,
disabilityisusedtorefertothephysical,mental,or
cognitivestatusoftheindividual.Althoughconsiderable
workhasbeendoneoverthelastfewyearstoward
clarifyingthemeaningofdisability,thereisstillsomeconfusioninvolvingterminology.However,researchersare
comingtomoreofaconsensusthatdisabilityisacomplex
phenomenonandthatneitherofthedefinitionsoutlined
aboveadequatelydescribesallthecharacteristicsofthe
phenomenon.
Thisschemeisonlyappropriateforpopulationhealth
change,notindividuallifecyclechange.Thecomplexityof
changeattheindividuallevelisshowninfigure1.2.Each
arrowrepresentsapotentialhealthchangeforanindividual.
Thesumofthesechangesacrossallindividualsis,of
course,whatproduceschangeinthepopulation.Any
individualcanskipstagesandmaynotnecessarily
experienceanystageotherthandeath.Individualscanalsoexperiencechangeinbothdirections,thatis,theymay
becomeimpairedandmayregainfunctioning.For
populations,however,theorderofhealthchangein
figure1.1isappropriate;onaverage,diseaseoccursfirst,
followedbyfunctioninglossanddisability,andfinally,
death.Thedifferencebetweenindividualsandpopulationsis
important inevaluatingthetypeofdataandmethodsused
forsummarymeasures.Informationontheindividual
processesrequireslongitudinaldataandmethods;
informationonthepopulationmaybecollectedas
cross-sectionalinformation.
1.2.2PastuseofsummarymeasuresSummarymeasuresofpopulationhealthcanbe
categorizedintotwomajorgroups.Thefirstmajorgroupof
measuresiscalledhealthexpectancy(HE),andincludes
measuressuchasdisability-freelifeexpectancy(DFLE)and
healthylifeexpectancy(HLE).Thesecondmajorgroup,
whichmeasureshealthgaps,includeshealthmeasuressuch
asdisability-adjustedlifeexpectancy(DALY)(19).Although
thesummarymeasuresthatindicateyearsofhealthyand
non-healthylifederivedfromthesetwogeneralapproaches
(andtheirmyriadvariations)maylooksimilar tothe
consumeroftheresearchfindings,summarymeasures
currentlyinusearebasedonavarietyofhealthoutcomes,
assumptions,andmethods.Thesedifferencesareimportantbecausetheyrelatetothevalidityandreliabilityofthe
measures.Becausetheoutcomesofallmeasuresappear
similarandareexpressedinyearsoflife,theymayallbe
equallyacceptabletothegeneralpublic;however,
researchersevaluatethepotentialusesoftheindicesquite
differently.Summarizinghealthismadeconsiderablymore
complexbytheneedformultiplemeasuresandtheneedto
lookathealthylifeasmeasuredinbothyearsandasa
percentageofremaininglifespentinthehealthystate.This
evidencesupportstheconclusionthattherearenosimple
measuresofhealth.
Healthylifeexpectancy(HLE)Thissummarymeasurethatlinkshealthdimensionsandmortalitywasproposedmorethan30yearsago(1,3).Themethodsdevelopedby
Sullivan,atNCHS,havebeenadoptedworldwideandare
thebasisfortheHLEfamilyofmeasures(20).(Seechapter
2fordetailsofthemethodology.) Asubstantialbodyof
workusingSullivansproposedsummarymeasuresandwith
modificationstofitavailabledatahasbeendevelopedover
thelast10years.Modificationstotheoriginalformulation
areduetothespecificdimensionofhealthusedindefining
healthylife.Oftenapplicationsofthismethodhavebeen
determinedbyavailabledatamorethananyclear theoretical
ideaofwhataspectofhealthisappropriate.Mostofthis
researchhasfocusedoncomparinglengthoflifeindifferent
healthstatesatvariouspointsintimeandacrosspopulationgroupsatonepointintime.
Theoriginallyproposedmeasurelinkedmortalityto
measuresoflong- andshort-termdisabilitytoestimatelife
withandwithoutdisabilityusingdatafromtheNational
Figure1.2.PotentialhealthchangesforindividualsSummaryMeasuresofPopulationHealth 3
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HealthInterviewSurvey(NHIS)(3). Yearslivedwith
disabilitycouldbefurtherdividedintosevereormoderate
disabilityandyearsoflifeinan institution.
Inthelast10years,anumberofadditionalapproaches
tomeasuringhealthylifeexpectancyusingdifferent
generalizationsofdisabilityorhealthhavebeendeveloped.
Forinstance,intheolderpopulation,disabilityhasoften
beenindicatedbytheinabilitytoperformActivitiesofDaily
Living(ADL)orInstrumentalActivitiesofDailyLiving(IADL),taskswhichreflectaninabilityto live
independently.Otherestimatesofhealthylifeexpectancy
havebeenbasedonmeasuresthatcategorizeyearsoflife
usingdiseasestatesor lossof cognitivefunctioningas
measuresofhealthstate.Forexample,healthylifeis
estimatedasyearswithoutheartdiseaseoryearswithout
impairedcognitivefunctioningordementia.
Measuresofhealthylifeexpectancyhavebeenusedto
trackandexplainchangesinpopulationhealth.Forexample,
researchbyCrimminsandassociateshasshownthatthe
1980swereaperiodwhenincreasesinlifeexpectancywere
concentratedinyearswithoutdisability; incontrast,gainsin
lifeexpectancyduringthe1970swereindisabledyears.Thisapproachhasalsobeenimportantindeterminingage,
socioeconomic,andracialdifferentials(21,22).Hayward
andHeron(1999)havelookedattherelationshipbetween
disabilityandlifeexpectancyforethnicgroupsinthe
UnitedStates;theirresearchhasshownthatsomeethnic
groupshavelongerlifebutworsehealth(Native
Americans)thanthenon-Hispanicwhitepopulation,while
othershavelongerlifeandbetterhealth(Asian
Americans)(23).
Thehealthylifeexpectancymeasuresdescribedabove
incorporatenominallydefinedstatesofhealth,andthey
estimatelifewithandwithouthealthinthesenominally
definedstates.Inordertoexpandtherangeofhealthincludedinthedefinitionofhealthylife,someresearchers
haveweightedstatesofhealthaccordingtoanindexof
healthproblemseverity.Measuresofhealthylifedeveloped
inthismannermayweightstatesthatcharacterizeone
dimensionofhealthorcombinehealthdimensionsintostates
whichareweightedtoproduceamultidimensionalindexof
healthylifeexpectancy.Thesemeasures,oftencalled
Health-AdjustedLifeExpectancies(HALE)or
Health-AdjustedLife Years(HALY),canuse awidevariety
ofdimensionstodefineasetofhealthstatestowhichthe
weightingschemeis thenapplied.Theseincludesocial
functioning,cognitivefunctioning,socialactivities,
psychologicalfunction,painandsymptoms,aswellasloss
infunctionanddisability.Theweightingschemesprovidea
numberrangingfrom 0 to 1 toreflectthequality oflifeor
thesocialutilityof thehealthstateindividuals
experience(24).Optimalhealthisvaluedat1;deathisvaluedat0.Thesemeasuresarethenintegratedwithlife
tablestoproducehealth-adjustedlifeexpectancy.Because
theweightsaresoimportantindeterminingtheoutcome,
andbecausetheyhavegreatsocialsignificance,mucheffort,
discussion,andevaluationhasgoneintoproducingthe
weightingschemesforuseinthesemeasures.Agreementhas
notbeenreached,however,on thevalidityofthevarious
schemes.
Insummary,measuresreflectinghealthylifeexpectancy
canbebasedonavarietyofdefinitionsofhealthandcan
utilizeavarietyofmethods.Nosinglemeasurehasbeen
agreeduponasthebestapproach.Theappropriatenessof
measuresdependsonthedimensionsofhealthofprimaryinterest(e.g.,disabilityordisease).If thereisadesireto link
thesemeasurestohealthpoliciesandprogramsandto
individualhealthbehaviors,thepointsof interventioninthe
healthprocessshouldbeconsidered (figure1.3).Observed
changesinthesemeasurescanreflectarangeof factors.
Healthylifeexpectancycanbebroughtaboutbychangesin
risk-relatedhealthbehaviors(becauseoftechnologicalor
medicaladvancementaffectingthediagnosis,treatment,and
progressionofdiseases)orbecausedisabilityhasbeen
reduced(bybetterintrinsichealthorbecausetheextrinsic
environmentbecomesmoreadaptedtopersonswith
functioningproblems).Consequently,careandadditional
dataarerequiredtointerprettheanalysesunderlyingthesestatistics.
Disability-AdjustedLifeYears(DALYs)The WorldBankand WorldHealth Organizationhavesupported a
projecttodevelopmethodstoevaluatethedistributionof
scarcehealthresourcesindevelopingcountries.Asaresult,
thereisnowagrowinginterestinanotherapproachto
summarymeasuresDisability-AdjustedLife
YearsDALYs(2532).DALYsrepresentanalternative
Figure1.3.Healthcareandpublichealth interventionopportunities4 SummaryMeasuresofPopulationHealth
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approachtosummarymeasureconstructionthatlinks
disease,disability,anddeath.Thisapproachestimatesyears
oflifelostfromdeathswhichoccurbeforesome
theoreticallyachievableage(e.g.,internationalreportsuse80
yearsformenand82.5yearsforwomen)andattributingthis
losstodeathrates.Next,yearslosttononfataldiseasesare
calculatedbylinkingtheincidenceofdiseasestodisability
levelsandlengthoftimewithdisability.DALYsdifferfrom
othermeasuresdescribedbecausetheyreflectyearslosttoill-healthinsteadofyearslivedwithill-health;another
differenceis that theylinktwomajordimensionsofhealth:
diseaseanddisability.
DALYsalsoincorporateweightstoreflecttheseverityof
disability,and,becauseoftheemphasisonhealthpolicyin
theinternationalapplications,DALYsincorporatean
additionaleconomicapproachtoweightingyearsof life.
Thisapproachgivescurrentyearsoflifehigherweightsthan
futureyearsoflife,andlifeintheproductiveyearsor
workingagesisgivenhigherweightsthanlifein
nonproductiveyears.Theseweightingschemesdramatically
affecthowyearsofhealthylifearecalculatedforpeopleof
differentagesaswellasforpeoplewithdifferentdisabilities.
Incontrasttothecross-sectionalSullivanapproachto
estimatinghealthylifeexpectancy,DALYshavebeen
developedasanincidence-basedmeasure,thatis,onethatis
basedon thetransitionintodiseaseordisability.Incidenceis
aflowmeasure,whereasprevalenceisa stockmeasure.
Researchershavelongrecognizedthatincidenceratesare
theoreticallypreferabletoprevalencedataforindicating
healthchange:incidenceratesreflectonlyrecentevents,
whileprevalencedatareflecteventsthatoccurredearlierina
personslifetime.Incidencerates,however,require
longitudinaldatafromlargesamples,andtheyusuallyare
notavailableformostconditionsorfornationallyrepresentativepopulationsofmostages.
Becausetheincidencedatarequiredforinputto the
DALYsdonotexist,theyhavebeenestimatedfrom
whateverepidemiologicalinformationcanbepieced
together.Forexample,community-basedsurveyslikethe
FraminghamStudyprovideasourceofinformationon
diseaseonset.Disabilitylevelsrelatedtodiseaseonsetwere
thendeterminedusingexpertopinions. Weightsfor the
valueof lifespentindisease-disabilitylevelswerethen
developedinaseriesofworkshopswithavarietyof
experts.
1.3PotentialSummaryMeasuresSuggestedforHealthyPeople2010
Afterdiscussingbothgeneralapproachestoestimating
summarymeasuresanda largenumberofspecific
approachestothesemeasures,workshopattendeeswere
askedtorecommendsummarymeasuresforconsideration
fortheHealthyPeople2010,keepingdataavailabilityinmind.Themostimportantrecommendationresultingfrom
thismeetingwasthat:
Nosinglemeasurecanadequatelyincorporateallaspectsof health and mortality. A set of summary measuresincludingbothmortalityandvariousaspectsofmorbidityor health that canbecalculatedfromexisting orcollect-abledatashouldbeproposedforHealthyPeople2010.Usingasetofmeasuresratherthanasinglemeasurewill
makeitpossibletotraceavarietyofhealthylifedimensions
andtonotedifferencesinvariousaspectsofhealth.Itwill
alsobepossibleto identifyprogressinsomedomainsofhealththathaveledtowhatappearstobedeteriorationin
otheraspectsofhealth.For instance,progressmadein
prolongingthelivesofpersonswithAIDS(broughtabout
byavarietyofpharmaceuticaldevelopments)may
lengthenaveragelife,increasethenumberofyearslived
withAIDS,leadtoanincreaseinthenumberofpeople
withAIDSinthepopulation,andchangethehealthstatus
ofthoselivingwithAIDS.Usingasetofsummary
measuresinsteadofasinglemeasurewillhelpclarifythe
meaningofchangeinthemostgeneralmeasuresand
disentangleeitherprogrammaticormedicalinfluences;
thus,progresstowardreachingHealthyPeople2010goalscanbebettermonitored.
Although the two types of measures,HLE andDALYs,were discussed,HLE measures were recommendedforHealthyPeople2010.Inaddition,allsuggestedmeasureswerebasedoncross-sectional data.Further investigationofthepropertiesofincidence-basedmeasuresneedstobecompletedbeforeusingthemforhealthmonitoring.Thesetofmeasuresrecommendedformonitoringthe
firstgoalofHealthyPeople2010includethefollowing:Yearsofhealthy lifedefinedaslifewithoutdisability:
Thisrepresentsoneofthemostgeneralsummarymeasures
asdisabilityisalatestageinfigure1.1andreflectspopulationhealthstatesofallthepriorhealthdimensions.
Becausedisabilityreferstotheinabilitytoperformexpected
tasks,thisdefinitionofyearsofhealthylifemayreflectthe
overallimpactofhealthproblems.Healthylifecanbe
definedaslifelivedwithoutanyhealthlimitationthat
preventsnormalactivity.Lifewithdisabilitycanbe
subdividedintolifewithsevereandmoderatedisabilityas
wellaslifewithlimitationinpersonalcare,work,or
school.Thistypeofmeasurecanclearlydefineand
characterizeahealthyyearoflife,thatis,ayearwithout
disability.
YearsofHealthyLife(asusedforHealthyPeople2000):ThesummarymeasurethatwasdevelopedforHealthyPeople2000representsmultipledimensionsofhealth(33).Itincludesbothdisabilityandtheindividualsassessmentofall
aspectsofhealth.Itshouldcontinuetobe includedamong
theHealthyPeople2010measuresforcomparisonovertimeandwithothermeasures.Thismeasureusesaweighting
scheme;thatis,itincludesseverityofhealthproblemsinthe
calculation.Itismoredifficulttodefinethemeaningofa
yearofhealthylifewiththismeasurebecauseitincorporates
multipleaspectsofhealth.
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Inadditiontothetwomeasuresabove,morenarrowly
definedmeasuresofhealthalsocanbethebasisofsummary
measuresthatarecomparableovertimeandacross
populationsubgroups.Measuresbasedonhealth-related
behaviors,functioning,disease,andself-assessedhealth,
coupledwithmortality,weresuggested.Theseadditional
measureshavethepotentialtoclarifywhichdimensionsof
healtharechangingandthuscanbelinkedtoprogramsand
policiesthatmightbecausinghealthchange.Suchmeasurescaninclude:
Yearsof lifewithoutfunctioningproblems:Summarymeasuresbasedon functioningcouldbedefinedbyabilityto
performcertainfunctions,suchaswalking,lifting,picking
upobjects,etc.For thispurpose,bothphysicalandmental
functioningshouldbeconsidered.
Yearsof lifewithoutspecifieddiseases:Summarymeasurescouldincludeyearswithoutavarietyofmajor
diseasesandconditions;theconverse,yearswithconditions,
couldalsobeestimated.
Yearsof life inexcellentorverygoodhealth:Self-perceivedhealthcanbeusedaloneina summary
measuretoreflectchangeinpeoplesassessmentof theirhealth.Lengthoflifeinexcellenthealthorinverygoodor
excellenthealthcanbeasummarymeasureascanyears
spentinpoorhealthorfairorpoorhealth.
Yearsof life livedwithgoodhealthbehavior:Thismeasurecanserveasasummarymeasureofyearsspent
withriskfactorsforsomeoftheotherhealthoutcomes.For
instance,theaverageyearswithnoriskyhealthbehavior
(e.g.,smoking,drinking,obesity,andnohealthcare)canbe
estimated.Estimatescanbebasedonsinglebehaviorsor
groupsofbehaviors. Yearswithoutanyriskbehaviorscan
alsobeestimated.
Alloftheproposedsummarymeasurescanbeconstructedwithavailabledataandshouldbeavailablefor
majorsubgroupsof thepopulation.Somecanbeconstructed
forsub-nationalgeographicalareassuchasStates.Allthe
recommendedmeasurescanbeusedtoreflectprogress
towardbothgoalsofincreasingthequalityandyearsof
healthylifeanddecreasinghealthdisparitiesastheycanbe
estimatedforgenderandmajorracialandethnicgroups.
1.4AvailabilityofDataforEstimating theProposedMeasures
Thesuggestedmeasurescanbeestimatedforanumber
ofyearsinthe1990susingavailabledatafromNHIS.
However,the1997redesignoftheNHISsurveywillmakeit
difficulttohavealengthyseriesforsomeof themeasures.
Forsubgroupsofthepopulation,itmaybenecessaryto
combineyearstoproducereliableestimatesforsomeage,
racial,andethnicgroups.Onenecessarycomponentofthe
measuresistheannuallifetableforthepopulationalong
withthelifetablesfor thesubgroupsofinterest.Lifetables
bysocioeconomicstatus(SES)arenotregularlyproduced
butcouldbeproducedusingdatasuchasthemortality
followupforNHIS.Considerationshouldbegiventothe
reliabilityofannualchangesofmortalityaswellashealth
data.
Itwillbeimportanttoapplythesemeasuresacross
variousgeographicandpoliticallevels,includingStatesand
municipalities.Manyofthesemeasurescanbeestimatedfor
States.Thepossibilityofestimatingthesestatisticsfor
smallergeographicareasneedstobeinvestigated.Estimates
fortheinstitutionalpopulationneedtobeincludedinthesummarymeasures.Estimatesofthesizeandcompositionof
therelevantinstitutionalpopulationaredifficulttoobtainbut
needtobepartofthemeasuresiftheyaretodescribethe
entirepopulation.Issuesofdataavailabilityforthe
institutionalpopulationneedtobeaddressed.
Thisreportpresentstheresultsofresearchconductedto
investigatevariousissuesofimmediateinterestfor
monitoringprogresstowardtheHealthyPeople2010goals.Healthylifeexpectancieswereestimatedusingdifferent
definitionsofhealth.Selectedestimatesforvarious
populationsubgroupsarepresentedin chapter 3.Allofthe
estimatespresentedinthechapterarecalculatedbasedon
healthdatafromNHIS.SinceNHISdoesnotincludetheinstitutionalpopulation,theestimatesin chapter 3mightbe
atvariancewithestimatesmadeincludingtheinstitutional
population.Thepossibleimpactofnotincludingthe
institutionalpopulationinestimatinghealthylife
expectanciesisdiscussedin chapter 5. Twootherimportant
pointsshouldbekeptinmindinreadingtheestimated
healthylifeexpectanciesin thisreport.First, theexpected
yearsofhealthylifepresentedinthisreportaredifferent
fromthe YearsofHealthyLife(YHL)usedinHealthyPeople2000 inboththeinterpretationoftheresultsaswellasinthemethodofcalculation.(Themethodofcalculation
andinterpretationofYHLusedinHealthyPeople2000isdescribedinStatisticalNotesno 7(33).)Second, thesurveyinstrumentsandmethodofdatacollectionofNHISwere
revisedin1997.However,sinceallNHISdatausedinthis
reportarefromsurveysconductedpriorto1997,the1997
revisionofNHISdoesnotaffecttheresultsofthisreport.
DatausedforthisreportaremainlyfromtheNCHSand
theU.S.CensusBureau.Themethodthatiswidelyusedfor
calculatinghealthylifeexpectationusingcross-sectiondata
isexplainedsuccinctlyfollowingthisintroductorychapter.
Expectedyearsofhealthylifeundervariousdefinitionsof
healthandvariationofresultsbymeasurearediscussedin
chapter 3.Chapter 4summarizestrendsinyearsfreeof
activitylimitationfortheperiod198595.Inadditionto
estimatinghealthylifeexpectancyunderdifferentattributes
ofhealthandlookingat trendsinlimitation-freelife,the
reportincludesatestoftheeffectofincludingdatafrom
differentsourcesonestimatedhealthyorlimitation-free
years.Anillustrationofthis impactanalysisispresentedin
chapter 5.Theoverallsummaryofthereportand
recommendationsforthelongertermendeavorofsolving
problemsofdataconstraintsandtheconstructionofmore
comprehensivemodelsofsummarymeasuresofhealthare
highlightedinthelastchapter.
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References1. SaundersB.Measuringcommunityhealthlevels.Am JPublic
Health54106370.1964.
2. SullivanDF.Conceptualproblems indevelopinganindexof
health. VitalandHealthStatistics,2(17):NationalCenterfor
HealthStatistics, Washington,D.C.1966.
3. SullivanDF. Asingleindexofmortalityandmorbidity.
HSMHSHealthReports86:34754.1971a.
4. SullivanDF. Disabilitycomponentsforanindexofhealth.VitalandHealthStatistics.2(42)NationalCenterforHealth
Statistics,Rockville,Maryland.1971b.
5. FriesJF. Aging,naturaldeath,andthecompressionof
morbidity. NEngl J Med303(3):1305.1980.
6. FriesJF.Thecompressionofmorbidity:Nearorfar. Milbank
Q67(2):20832.1989.
7. MantonKG.Changingconceptsofmorbidityandmortalityin
theelderlypopulation.MilbankQ:HealthSociety60(2):
183224.1982.
8. Gruenberg EM.Thefailureofsuccess.MilbankQ:Health
Society55(1):324.1997.
9. U.S.DepartmentofHealthandHumanServices,Officeof
DiseasePreventionandHealthPromotion.Healthypeople
2000. Washington,D.C.1991.10. U.S.DepartmentofHealthandHumanServices.Healthy
people2010.2nded. Withunderstandingandimproving
healthandobjectivesforimprovinghealth. 2vols.
Washington,D.C.:U.S.GovernmentPrintingOffice.2000.
11. FieldMJ, GoldMR.(eds).Summarizingpopulationhealth:
Directionforthedevelopmentandapplicationofpopulation
metrics.InstituteofMedicine,NationalAcademyPress,
Washington,D.C.1998.
12. U.S.DepartmentofHealthandHumanServices.Leading
indicatorsforhealthypeople2010: AreportfromtheHHS
workinggroupon sentinelobjectives.U.S.Government
PrintingOffice. Washington,D.C.1998.
13. CrimminsE,HaywardMD,Saito Y.Changingmortalityand
morbidityratesandthehealthstatusandlifeexpectancyoftheolderU.S.population.Demography31:15975.1994.
14. VerbruggeL.Disabilityinlatelife.InAgingandqualityof
life.AbelesR,GiftH,and Ory M.(eds).pp.7998.Springer,
New York.1994.
15. WorldHealthOrganization.Internationalclassificationof
impairment,disabilitiesandhandicaps: A manual of
classificationrelatingto theconsequencesofdisease.Geneva.
1980.
16. VerbruggeLM,JetteAM.Thedisablementprocess.SocSci
Med38(1):114.1994.
17. CrimminsE,HaywardMD,Saito Y.Differentialsinactivelife
expectancyin theolderpopulationof theUnitedStates. J
Gerontol BPsycholSciSocSci51(B3):S111S120.1996.
18. BrandtEN,PopeAM.Eds.EnablingAmerica:Assessingtheroleofrehabilitationscienceandengineering.Divisionof
HealthSciencesPolicy,InstituteofMedicine,National
AcademyPress, Washington,D.C.1997.
19. MathersE.Healthexpectancies:anoverviewandcritical
appraisal.InSummarymeasuresofpopulationhealth:
Concepts,ethics,measurementandapplications.C.J.L.
Murray,etal. (eds).pp.177204.WHO,Geneva.2002.
20. JaggerC.HealthexpectancycalculationbytheSullivan
Method: Apracticalguide.Euro-REVES.1997.
21. CrimminsE,Saito Y,IngegneriD.Changesinlifeexpectancy
anddisability-freelifeexpectancyintheUnitedStates.
PopulationandDevelopmentReview15:23567.1989.
22. CrimminsE,Saito Y,IngegneriD. Trendsindisability-free
lifeexpectancyintheUnitedStates19701990.Population
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23. HaywardMD,HeronM.Racialinequalityinactivelife
amongadultAmericans.Demography36(1):7791.1999.24. FrybackD.Methodologicalissuesinmeasuringhealthstatus
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patternsin 1990.Bulletinofthe WorldHealthOrganization
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26. MurrayC,LopezA.Quantifyingdisability:Data,methods,
andresults.Bulletinofthe WorldHealthOrganization
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2020.Cambridge:HarvardUniversityPress.1996b.
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2. MethodsforCalculatingHealthyLifeExpectancy2.1 Introduction
Healthylifeexpectanciesarecalculatedusingmodelsthatincorporatemeasuresofmortalityandmorbidityas
schematicallypresentedin figure2.1(1).
Age-specificdeathratesaccountforthemortality
component.Age-specificratesofpopulationmorbidity,
disability,or someotheraspectofhealthaccountforthe
morbiditycomponent.Thesetwocomponentsarecombined
usinga mathematicalfunctionthattransformsthetwosetsof
partialmeasuresintoasinglecompositemeasureusinga life
tablemethodology.Figure2.2displaystheframeworkofthis
calculation,includingthetypeofdataneededandthe
techniquesusedtoestimatethetwocomponentsofthe
measureatthenationallevel.
NationalmortalitydataareobtainedfromtheNationalVitalStatisticsSystemofNCHS.Mortalitydataarecollected
byeachStateandtheDistrictofColumbiaandcompiledat
thenationallevelbyNCHS.Mid-yearpopulationestimates
arefromtheU.S.CensusBureau.
Healthdatacancomefromanumberofdifferent
sources,dependingonthetypeofhealthmeasureandthe
populationbeingconsidered.Therangeofitemsthatcould
beusedtocharacterizehealthisillustratedbyahealthstate
classificationsystemdeveloped byBoyleand Torrance
(displayed,inpart,infigure2.3) (2).Theclassification
systemofBoyleand Torranceconceptualizesthe
interrelationshipofhealthattributesashierarchal,basedon
breadthandoncoverageofdifferentaspectsofhealth.Forexample,physicalfunction,whichisoneoftheprimary
healthattributes,hasfoursecondaryattributes,oneofwhich
isself-care.Self-caremay, inturn,bedisaggregatedinto
morespecifichealthattributes,shownasthethirdlevelof
classificationinfigure2.3.
Theestimationofhealthylifeexpectancybeginswiththe
calculationoflifetablevaluesfollowedbythecalculationof
age-specificprevalenceratesofbeinghealthyandnotbeing
healthy.Theformulasneededtocalculatethelifetable
valuesforanabridgedlifetablearesummarizedinsection
2.2.1. Tocalculatetheage-specificprevalenceratesofbeing
healthy,firstcalculatetheratesofreportingfairorpoor
health (nx).Theratesofbeinghealthy,thatis,reporting
goodorbetterhealthisthen(1nx).Thenforeachage
interval (x,x+n),theratesofbeinghealthy(1nx)aremultipliedbythetotalnumberofyearslivedwithinthe
sameageinterval (nL
x).Thiscalculationprovidesan
estimateofthetotalnumberofyearsagroupofpersonsare
expectedtoliveinahealthystateduringtheinterval.The
ageinterval (n,n+x)equals 1forsingle-yearagegroups;itequals 5 ifdatausedarein5-yearagegroupsand10for
10-yearagegroups.ThemodelusedtoestimateHLE(i.e.,
theexpectednumberofyearsingoodorbetterhealth)is
summarizedinsection2.2.2.
Healthylifeexpectancycouldbeestimatedusingavarietyofhealthattributes.Forinstance,themodelmaybe
usedtoestimatedisability-freelifeexpectancyorlife
withoutactivitylimitation,alsoreferredtoasexpectedyears
ofactivelife.Regardlessofthehealthattributechosen,the
modelusestwoseparateandindependentpartialhealth
measures:(1nx)forthemorbiditycomponentandlx and
nLx forthemortalitycomponent.
2.2TheLifeTableTechniqueThelifetable,alsoknownasthemortalitytable,isused
topresentthemostcompletestatisticaldescriptionof
mortality(3).Thelifetablealsohasbeenanimportanttoolfordemographerswhoareinterestedinestimatingthe
probabilityofmarriageandremarriage,widowhood,
orphanhood,andinmigrationandpopulationprojections(4).
Abriefsummaryofthemethodcommonlyusedtoestimate
lifetablevalues,healthylifeexpectancy,andthestandard
errorsofHLEwillbepresentedintheremainingpartsof
thischapter.Foramoredetailedexplanationofthemethod
withillustrativeexamplesandtheassociatedsensitivity
analysis,refertoHealthyPeople2010StatisticalNotes,No.21andNo.22(5,6).
2.2.1Estimatingtheaverageexpectationof lifeTheobjectiveofthelifetableistocalculatetheexpected
numberofyearslived,ifagroupofpeople,currentlyagex,
livedtherestof theirlivesexperiencingalltheage-specific
mortalityratesobservedforthepopulationataspecifictime.
Theestimationof lifetablevalues,suchastheexpectation
oflife,beginswiththecomputationofage-specificdeath
rates.Thetwosetsofdatarequiredtoconstructalifetable
arethemid-yearpopulationandthenumberofdeathsinthat
year.Thesedatacouldbeanalyzedinsingleyearsofageor
5- or10-yearagegroups.(Methodsforconstructinga
completeannuallifetablearediscussedinNCHS Vitaland
HealthStatistics,no.129.)(7)Theprocesscouldbeapplied
totheconstructionofalifetablefornational,State,orlocalpopulations.
TheestimationbeginswithcountsforthepopulationnPx
anddeathsnDx foreachagegroup.Populationcountsare
basedonmid-yearestimates.Deathsarefortheentireyear.
Theseareusedtocomputetheaveragedeathrateofeach
agegroupfortheyear (nM
x,wheren,thenumberofyearsin
theagegroup,can be 5 or 10years),as
nMx = nDx /nPx . [1]
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Thecomputedage-specificdeathratesneedtobechecked
forstability.Age-specificdeathratesareconsideredtobe
stableiftheyarebasedon20ormoredeaths.Ratesbased
onfewerthan20deathshavea relativestandarderrorof
23percentormoreandthereforeareconsideredhighly
variable.(8)
Theconditionalprobabilityofdyingwithinagivenage
groupnqx istheproportionofpeopleintheagegroupaliveatthebeginningoftheageintervalwhodiebeforereachingthenextagegroup.Whereas
nM
x isanannualdeathrate,nqxisaconditionalprobabilityofdying.Thisprobabilityis
estimatedas:
nqx= [nnMx] / [1 + n(1ax) nMx] , [2]wherea
x istheaverageproportionofyearslivedbythosewhodiedinthisageinterval.Theconditionalprobabilityof
dyingisassumedtobe1.0fortheopen,oldestageinterval.
Intheexamplepresentedhere,n is 5years,sotheprobabilitybecomes:
5qx = [55Mx] / [1 +5(1ax) 5Mx] .
Thevaluesforax areconstantsderivedfromthecompletelifetables(9).Forsingle-yearlifetablevaluecalculations, axmaybeassumedtobe.
Havingcalculatedtheconditionalprobabilityofdying,
onecannowcalculatetheprobabilityofsurvivingtoan
exactagemarkingthebeginningofaninterval.Inthelife
table,thisisexpressedasthenumberofpersonssurvivingto
anexactage(ortheexactageatthebeginningofanage
intervalwhengroupdataareused),startingwithanassumed
cohortpopulation (l0)frequentlyexpressedas100,000at
birth.Foranyotheragex,thenumberofsurvivorsatthat
agelx canbecalculated.Hence,thenumberaliveatexact
agex+n (lx+n) iscalculated bymultiplyingthenumber of
survivorsatexactagex (lx) bytheprobabilityofsurviving
fromagex toagex+n(1nqx)or:lx+n=lx(1nqx) . [3]
Thetotalnumberofperson-yearslivedfor thosepeoplewho
werealiveatthebeginningoftheageintervalx tox+n isthenthesumofthetotalnumberofyearslivedby
individualssurvivingtotheendoftheageintervalplusthe
totalnumberofyearslivedbythosewhodiedintheage
interval.Thisbecomes:
nLx=n {lx+n +ax (lxlx+n)}. [4]Intheexamplepresentedhere,n= 5so,
5Lx = 5{lx+5 + ax (lx lx+5)} .Theperson-yearsremainingforthepopulation,thatis,
Tx, issimplythe totalofalltheperson-yearsforagexand
allsubsequentagegroups,or:
Tx= nLifori=x,x+n,...,oldestagegroup. [5]Theaverageexpectedyearsperpersonisthenthetotal
person-yearsdividedbythenumberofpersonssurvivingto
thebeginningoftheageintervalx,or:
ex= Tx / lx . [6]2.2.2Estimatinghealthy lifeexpectancy
Thelifetabletechniqueis apowerful toolforestimating
theremainingyearsoflifethatagroupofpersonswould
Figure2.1.Aschematicpresentation ofthemodelSOURCE:AdaptedfromamodelbytheInstituteofMedicine,NationalAcademyofSciences,1998.
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Figure2.2.Aschematicframeworkforestimatinghealthylifeexpectancyatthenational levelusingrespondent-assessedhealthstatusasanexample
Figure2.3.ExampleofattributesforhealthclassificationsystemSOURCE:BoyleandTorrance. Developing Multi-attributeHealthIndexes. MedicalCare,1984.
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expect toliveoncetheyhadreachedacertainage.Regardlessoftheirage,theremainingyearsof lifemightbelived ingoodhealthorin lessoptimalhealthstatesorsomecombinationofboth.Thetraditionallife table techniquedoesnotdistinguishbetweenremaininghealthyyearsandunhealthyyears.Additionaldataareneeded todisaggregatethe totalnumberofyearsintoexpectedyearsofhealthyandofunhealthy life.
Thetotal
number
of
expected
years
of
life
are
partitioned
intohealthyandunhealthyyearsusinghealthdata(figure2.2).Ingeneral,healthdata,collectedthroughhealthsurveysorfromclinicalobservations,areused toestimatetheprevalenceofdifferenthealthstates.Thepopulation isthenpartitionedintoproportions thatareexperiencingvaryingstatesofhealth.Thepartitionmaybeassimpleasdividing thepopulationintothosewhoarehealthyand thosewhoareunhealthy.Or,thepopulationmaybepartitionedintomore than twopopulationsubgroups,accordingtovaryingdegreesofhealth,usingmultidimensionalscaling todescribehealthstates.
TocalculateHLE,thepopulationofeachageintervalinthe lifetable ispartitionedintotheproportionexperiencinganunhealthycondition(5x)andthosethatareconsideredhealthy(1
nx).SincenLx isthe totalnumberofperson-yearslivedforthepopulation inage intervalxtox+n(equation5), theproportionof theseyears livedinahealthystate(
nL
x) isthen:
xLx=(1nx)nLx. [7]
Oneofthefollowing twoequationscanbeused todetermineHLE:
w1
e x=lx nLx.i =x [8]
orw
1e x=lx (1ni)nLi
i =x [9]where
ex isHLEatagex,orthenumberofremainingyears
ofhealthy lifeforpersonswhohavereachedagex;lx isthenumberofsurvivorsatagex;(1nx) represents theage-specificrateofbeinghealthy;nLx isthe totalnumberofyearslivedbyacohort intheageinterval(x,x+n);andw istheoldestagecategory.
Theexpectedyearsofunhealthylife isexex.However,
ifmultiplestatesofhealthstatusaredescribed,theprevalenceforeachofthosestatesforeachage intervalmustbecalculated.Equationssimilarto[8]and[9]areusedtoestimateseparatelytheexpectedyearsof lifein thosehealthstates.
2.2.3Standarderrorsofhealthy lifeexpectancyTheestimatesforage-specificprevalenceofhealthyand
unhealthystatesarederivedfromsurveysorsamples.Consequently,theseestimateshaveassociatedsamplingerror.Calculating thestandarderrorof theresultingestimatedHLEisespecially importantwhencomparingpopulationsubgroups.Thissectiondiscusses themethodofestimating thestandarderrorsofHLE,withandwithoutinformationonthesurveysampledesign.Standarderrorsfortheother lifetablevaluescanbecalculatedseparatelywhenneeded.SeeChiangandKeyfitzfordetails(10,11).
Eachage-specificvalueof theprevalenceof thepopulationexperiencinghealthylife,(1
nx), isanestimated
proportionwithanassociatedvarianceandstandarderror.Thevariancesoftheseproportionsandtheirstandarderrorsmaybeestimatedusingroutinestatisticalmethods.Consequently,thevariance(S2) isgivenbythebinomialvarianceof:
S2(nx) = [nx(1nx)]/nNx, [10]wherenNx is thenumberofpersonsin theage interval(x,x+n)ofthesamplefromwhichtheprevalencerateswerecomputed.
Thevariancesof theprevalenceratesfromequation10canbeusedtoestimate theoverallvarianceofex usingthe
followingformula:w
1VAR(ex) = 2 [nLi2S2(1ni)].lx
i =x [11]IllustrativeapplicationsofthevarianceofHLEusing1995U.S.populationdataarepresentedinHealthyPeople2010Statistical
Note
No.
21
(5).
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7. AndersonRN.MethodsforconstructingcompleteannualU.S.lifetables.NationalCenterforHealthStatistics.VitalHealthStat2(129).1999.
8. NationalCenterforHealthStatistics.VitalstatisticsoftheUnitedStates,1992,volII,mortality,partA.Washington:PublicHealthService.1996.
9. SirkenMG.Comparisonoftwomethodsofconstructingabridgedlifetablesbyreferencetoastandardtable.NationalCenterforHealthStatistics.VitalHealthStat2(4).1966.10. ChiangCL.Astochasticstudyofthelifetableanditsapplication:II.Samplevarianceoftheobservedexpectationof lifeandotherbiometricfunctions.HumBiol32:22138.1960.
11. KeyfitzN.Introductiontothemathematicsofpopulationwithrevisions.Cambridge,MA:AddisonWesley.1968.
12 Methods forCalculatingHealthyLifeExpectancy
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3. Expected Years of Healthy Life Under Various Definitions of Health
3.1 Introduction
Nosingledefinitionofthecomponentofhealthy lifeexpectancymeasures thenonfatalhealthoutcome.Prevalenceorincidenceofhealth-relatedoccurrencesarenumerousandmeasuredifferentaspectsofhealth.Theseincludeself-ratedhealthormeasuresofwork,activity,orfunctional limitations.Theycouldalsobeobservedratesorprobabilitiesoftheoccurrenceofbadphysicalormentalhealth,acuteorchronicconditions,health-relatedbehaviors,orevenhealthserviceutilization.Inthischapter,thepracticalapplicationof thecompositemeasureisillustratedbycombiningvariousnonfatalhealthoutcomemeasureswith lifetablevalues;thesecombinationsareusedtoestimateavarietyofhealthylifemeasuressuchasexpectedlife
in
good
or
better
health,
free
of
activity
limitation,
or
withoutneedinghelp inADLorIADL.
Healthy lifeexpectancywillbeestimatedfirstasexpectedyearswithouthealth-related limitation.That is,theprevalenceofactivity,work,andfunctional limitationswillbeusedasthenonfatalmeasure.Second,healthylifeexpectancyfrom theperspectiveofdiseasesorchronicconditionswillbediscussedusingtheprevalenceofchronicarthritis,heartdiseases,hypertension,anddiabetes.Prevalenceofoverweightandobesityamongadultswillbeused todiscusshealthylifeexpectancyasameasureofhealth-relatedbehavior.
Healthy lifeexpectanciesareestimatedby5-yearagegroupandsex.Estimatesarealsopresentedbyracewheneverdatabyraceareconsideredreliable.Datafromvarioussourcesareusedfortheestimates.Lifeexpectanciesby5-yearagegroup,sex,andraceareestimatedusingdatafromNCHSand theU.S.CensusBureauasdescribedinchapter2.Prevalenceratesof thevarioushealthstatesarecalculatedfromthepersonandconditionfilesofNHISfortheyears198596.3.2 Expected Years of Healthy Life for Malesand Females
Asnumerousstudieshaveshown thathealthylifeexpectanciesvaryconsiderablybothbyageandsex(14),disparitiesinhealthy lifeexpectancieswillbediscussedforsubgroupsdefinedbythesefactors.Measuresusedforthediscussionincludeexpectedyears ingoodorbetterhealth,years inexcellenthealth,yearswithoutactivitylimitation,yearswithoutwork limitation,yearswithoutlimitation inADLorIADL,andyearswithoutdiseaseorchronicconditions.
3.2.1 Expected years in good or better health
Expectedyears
of
life
is
first
measured
using
expected
yearsingoodorbetterhealth.First,respondentswhostatedthat theywere ingood,verygood,orexcellenthealthwereclassifiedaspersonsingoodorbetterhealth;respondentswhoassessedtheirhealthasfairorpoorwereconsideredpersonsinpoorhealth.Expectedyearsofhealthylifecanalsobeestimatedusingexpectedyears inexcellenthealth.Toestimateexpectedyears inexcellenthealth,respondentswereclassifieddependingonwhethertheirself-assessedhealthwasexcellent.Figure3.1presentsthedistributionofthosereportinggoodorbetterhealthby5-yearagegroupandsex.Thepercentageofthosewhowere ingoodorbetterhealthdeclineswithage,slowlyforyoungeradults,butrelativelyfasterforolderadults.Theestimatedyearsingoodorbetterhealthandinexcellenthealthforselectedagesbysexarepresentedalso intable3.1.
The tableindicatesthat in1995,anewbornbabywouldexpectto live75.8years(72.8yearsformalesand78.8yearsforfemales).Of thistotalexpectedlifespan,66.5years(87.7percent)wereexpectedtobeingoodorbetterhealth,whereasonly26.4years(34.8percent)wereexpectedtobeinexcellenthealth.Expectedyearsofhealthy life,measured inyearsaswellasapercentageof total lifeexpectancy,variesbyage.Asonegetsolder,years ingoodorbetterhealthdecreaseinbothabsoluteandrelativeterms.In1995,forexample,apersonatage20wouldexpecttospend84.3percentofhisorherfuture lifeingoodorbetterhealthandonlyabout29.0percent inexcellenthealth.Atage65, thesepercentagesdeclinedto71.0percentand14.9,respectively.
Expectedyears ingoodorbetterhealthandinexcellenthealthalsovariedbysex.Femalescouldexpect tolivemoreyearsingoodorbetterhealththan theirmalecounterparts.Ontheotherhand,malescouldexpectarelativelyhigherproportionoftheirfuture lifeingoodorbetterhealthat theyoungerageswhereasfemalesseemslightlybetteroffafterage65(figure3.2).Whenhealthy lifeismeasured in termsofexpectedyears inexcellenthealth,malesatyoungerageswouldexpecttospendmoreyearsandahigherproportionoftheir livesinexcellenthealth thanfemales.Theoppositewas trueafterage75.Thetablealsoindicatesthatas thepopulationages,thedifference inhealthylifebetweenmalesandfemalesdeclinesslightly,especiallywhenhealthy lifeismeasured inyearsratherthanasapercentof lifeexpectancy.Thedifferencebetweenexpectedyears ingoodorbetterhealthformalesandfemales isstatisticallysignificant(p
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Figure3.1.Percentageofpersonsreportinggoodorbetterhealth,byageandsex:UnitedStates,1995
3.2.2 Expected years without activity limitation
Inthe1995NHIS,respondentswereaskedaboutactivitylimitation.Respondentswerecategorizedintooneofthefollowinggroups:notlimitedinanyway;unabletoperformtheirmajoractivity;limitedeither inkind/amountof theirmajoractivity;andlimitedinactivitiesother than theoneidentifiedasthemajoractivity.Respondentswithunknownactivitylimitationstatuswereassumed tobenot limited(5).Expectedyearsofhealthy lifedefinedasdisability-free lifeexpectancy(DFLE)wereestimatedbasedontheprevalenceofmajoractivitylimitationonlyandonanytypeofactivitylimitation.Thedistributionofthosefreeofanyactivitylimitationby5-yearagegroupandsex ispresented infigure3.3.Thefigure indicatesthatactivitylimitation isafunctionofage.Thepercentageofmalesandfemaleswithoutanyactivitylimitationdeclineswithageataslowerrateat theyoungeragesandarelativelyfasterrateat theolderages.
Theexpectedyearswithoutmajoractivitylimitationandyearswithoutany limitationforselectedagesbysexispresented intable3.2andfigure3.4.Onaverage,individualsofallagescouldexpecttospendmore than4ofevery5yearswithoutlimitation intheirmajoractivity.Ababybornin1995wouldbeexpected tospendmore than94percent(94.1formalesand94.7percentforfemales)ofhisorhertotal lifeexpectancywithoutlimitation inmajoractivity.Atage65,thispercentagedroppedonlybyabout5percentagepoints to89.1percent(88.6formalesand89.5percentfor
females).Ontheotherhand,when thebroaderdefinitionofthemeasureanyactivity limitationisused, thepercentageoflifeexpected tobewithout limitationdeclinedfrom94.4to82.5percentatbirth(from94.1to83.2percentformalesandfrom94.7to81.9percentforfemales)andfrom89.1 to61.3percentatage65.
Femalescouldexpect to livemoreyearswithoutmajororanyother typeofactivity limitation.Thedifferencebetweenmalesandfemalesinexpectedyearswithoutmajor
Figure3.2.Percentageofexpected life ingoodorbetterhealthatbirth,20,and65yearsofage,bysex:UnitedStates,1995
14 ExpectedYearsofHealthyLifeUnderVariousDefinitionsofHealth
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Figure3.3.Percentagefreeofactivity limitation,byageandsex:UnitedStates,1995
activitylimitation isstatisticallysignificant(p
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Figure3.4.Percentageof lifeexpectancyfreeofanyactivitylimitationatbirth,20,and65yearsofage,bysex:UnitedStates,
food;shoppingforpersonal items;managingmoney;usingthe telephone;anddoingheavyworkaroundthehouse(5).Therecodedresponsecategorieswerepersonswhoneedthehelpofotherpersonstoperformpersonalcareneeds,thosewhoneedthehelpofotherpersonstoperformotherroutineneeds,andthosewhoarenotlimitedinperformingpersonalorroutineneeds.Thosewithunknownlimitationstatuswereassumed tobenot limited inperformingpersonalcareorotherroutineneeds.Figure3.5
presentsthepercentagedistributionof thosewhowereabletoperformpersonalcareneedsorwhowerenot limited inotherroutineneedsofdailylivingby5-yearagegroupandsex.Thedistribution indicates thatlimitation inpersonalcareorotherroutineneedsofdailylivingwasahealthproblemmostlyassociatedwitholdage.Expectedyearswithoutfunctionaldependencywerecalculated,andtheresultsforsomeselectedagesbysexarepresented in table3.4.
Accordingto
the
results
of
the
1995
NHIS
data,
those
whowereyounger thanage75couldexpect tolivemorethan90percentoftheirremaininglifewithoutfunctionaldependency.A75-year-oldmalewouldexpect toliveabout90.2percentofhis totalexpectationoflifewithoutfunctionaldependency.Thepercentagedeclined toonly88.1percentatage80.Atage75,onaverage,adultfemaleswouldexpecttolivenearly88percentof theremainderoftheirlivesfreeoffunctionaldependency.Onaverage,an80-year-oldfemalewouldexpectto live83.4percentofherlifeexpectationfreeoffunctionaldependency.
Whenyearswithout limitationweremeasuredin termsoffunctionaldependencyduetolimitationsinADLorotherroutineneeds(IADL),adultsyoungerthan65yearsofagecouldexpectto livemorethan80percentof theirexpectedlivesfreeof limitation(morethan86.5percentformalesand80.1percentforfemale).Atanygivenage,femaleswouldexpectto livemoreyearswithoutfunctionaldependencybecauseofADLorIADLlimitation.Thedifferencebetweenmalesandfemales inexpectedyearswithoutADLorIADL
Figure3.5.Percentageabletoperformpersonalcareneedsornotlimitedinotherroutineneeds,byageandsex:UnitedStates,199516 ExpectedYearsofHealthyLifeUnderVariousDefinitionsofHealth
1995
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Figure3.6.Percentageof lifeexpectancyabletoperformpersonalcareneedsornot limited inotherroutineneedsat45,65,and75yearsofage,bysex:UnitedStates,1995
limitation isstatisticallysignificant(p
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weight in thecalculationofBMIsresultsin theover-estimationofexpected lifewithBMI less than25andwithBMI lessthan30.
Thepercentageofadult lifeexpectancyexpectedtobespentwithBMI lessthan25decreasedcontinuouslywithageforyoungeradultsandthenroseat theolderages.Byage65,thepercentagewas50.4,andbyage80,itwas63.6percent.Ateachage,adultfemalesexpectedtospendalarger
share
of
their
future
years
with
aBMI
less
than
25
thandidadultmales.Atage20,forexample,whileadultfemalescouldexpect tospend57.2percentoftheiraveragelifeexpectancywithaBMI less than25;theshareofaveragelifeexpectancyforadultmalesof thesameagewasonly40percent.Atage65, thepercentageof lifeexpectancytobespentwithaBMIlessthan25rosetoabout54percentforadultfemalesbutwasexpectedtobeonly50percentforadultmales.
Thetablealsoshowsthat,onaverage,adultsaged20yearsandovercouldexpecttospendmorethanfourfifthsoftheirliveswithoutbeingobese(BMIlessthan30);theyalsocouldexpectthepercentageofremaininglifeexpectedtobespentwithoutbeingobesewouldrisewithage,forbothadultmalesandfemales.Atage20,onaverage,adultfemalescouldexpect tospend83.4percentoftheirexpectedliveswithBMIlessthan30,whileadultmalescouldexpecttospend84percentof theirremainingliveswithanaverageBMI lessthan30.Atage65, theaveragepercentageofremaining lifeexpectedtobespentwithaBMIof less than30was84.2forfemalesand88formales.Becauseoftheirhigher lifeexpectanciescompared tomalesofthesameage,adultfemalesexpected tospendmoreof theirremainingyearswithaBMIoflessthan25aswellasaBMIoflessthan30.ThedifferencebetweenmaleandfemaleexpectedyearswithBMI lessthan25andBMIlessthan30issignificant(p
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Figure3.11.Percentageingoodorbetterhealth,byageandrace:UnitedStates,1995
expectancyforawhitemale;yet,itwasonly60.1percentfora65-year-oldblackmale.
Thelasttwocolumnsofthe tableshow theracialdifferencesbothinlifeexpectancyandexpectedyears ingoodorbetterhealth.Formalesaswellasfemales, thedifferenceinyears ingoodorbetterhealth islargerthanthedifferencein