Presented at The 129th Annual Meeting of the American Public Health Association Atlanta, GA, October 21–25, 2001

Presented by Kristine R. Broglio Thomas J. Hoerger James P. Boyle Amanda A. HoneycuttLinda S. GeissTheodore J. Thompson

Forecasts of Diabetes in the U.S.: Results from a Markov Model

P.O. Box 12194 · 3040 Cornwallis Road · Research Triangle Park, NC 27709Phone: 770-234-5014 · Fax: 770-234-5030 · honeycutt@rti.org · www.rti.org

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Background

In 1997, 10.3 million people in the U.S. were estimated to have diagnosed diabetes 35% higher than the estimated number in 1992

Diabetes prevalence is highest among the oldest age groups and among certain racial/ethnic minorities Future changes in diabetes prevalence may be

expected given projected changes in the size and age/racial composition of the U.S. population and life expectancies

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Study Objectives

Generate forecasts of diabetes prevalence and the number of people with diabetes through 2050 by age, sex, and race/ethnicity

Use a dynamic modeling approach to predict the number of people with diabetes in each year based on flows into and out of the diabetes “state”

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Overview of Previous Studies

Forecasts of the number in the U.S. with diabetes Helms (1992) — 12 million in 2050 King, Aubert, and Herman (KAH; 1998) — 22 million in

2025 (diagnosed and undiagnosed) Boyle et al. (2001) — 29 million in 2050

Limitations of previous studies Assume constant prevalence (or linear trend)

Prevalence is not determined based on flows into (incidence) or out of (death rates) the diabetes state

Most do not account for prevalence differences across race/ethnicity (e.g., Helms and KAH)

Generate forecasts for age groups (e.g., 0 to 44 years), rather than individual ages

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Methods — The Markov Modeling Approach

Markov models are used to simulate the progression of individuals through mutually exclusive disease states

3 states of the diabetes forecasting model: no diabetes, diabetes, and death

Age, race/ethnicity, and sex-specific subgroups transition between states in each 1-year cycle of model age (0 to 100 years, plus 101+) sex (male, female) race/ethnicity (non-Hispanic White, non-Hispanic Black,

Hispanic, and Other)

Total number of subgroups = 816

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Markov Model of Diabetes Disease States and Transition Probabilities

Diabetes

Death

Forecasts ofLive U.S.

Births

DiabetesIncidence

Mortality,People without Diabetes

Mortality,People with

Diabetes

Net Migration

No DiabetesDiabetes

Death

Forecasts ofLive U.S.

Births

DiabetesIncidence

Mortality,People without Diabetes

Mortality,People with

Diabetes

Net Migration

No Diabetes

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Data for Model Inputs (I)

Base Year (1999) Diabetes Prevalence Estimated using NHIS for 1980–1998 Used to determine initial distribution of individuals across

the Diabetes and No Diabetes states

1999 Diabetes Incidence Estimated using NHIS for 1984–1998 Age-, race/ethnicity, and sex-specific incidence rates

used to forecast the flows of individuals into the Diabetes state

Base model assumes no temporal changes in incidence

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Data for Model Inputs (II)

Baseline U.S. Population Census Bureau — middle series of population projections Used to determine initial distribution of individuals across

Diabetes and No Diabetes states

Forecasts of the Number of Live Births Census Bureau — forecasts of number of children under

one year of age through 2050 Added to No Diabetes state in each model cycle

Forecasts of Net Migration Census Bureau — middle series of population projections

through 2050 Added to Diabetes and No Diabetes states based on

age, sex, and race/ethnicity-specific 1999 prevalence

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Relative Risk of Mortality

Age Group Males Females

18 to 44 6.5 8.845 to 64 3.0 5.365 to 74 2.3 3.475 and older 2.1 2.1

Data for Model Inputs (III)

Forecasts of the U.S. Population Mortality Rate Census Bureau — mortality rate projections through 2050 Used to estimate Diabetes and No Diabetes mortality rates

(in conjunction with 1999 prevalence and estimated relative risk of death from diabetes)

Estimates of the Relative Risk of Mortality from Diabetes From Tierney et al. (2000)

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Results — Forecasts of the Number of People with Diabetes, 1999–2050

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

1999 2004 2009 2014 2019 2024 2029 2034 2039 2044 2049

Year

Nu

mb

er

10.9 million

25.3 million

35.5 million

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Results — Forecasts of Diabetes Prevalence, 1999–2050

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

1999 2004 2009 2014 2019 2024 2029 2034 2039 2044 2049

Year

Ra

te (

Pe

r 1

00

)

7.58 %

8.97 %

3.99 %

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Results — Forecasts of Diabetes Prevalence, by Race/Ethnicity, 1999–2050

0

2

4

6

8

10

12

14

1999 2004 2009 2014 2019 2024 2029 2034 2039 2044 2049

Year

Ra

te (

Pe

r 1

00

) Non-Hispanic Blacks

Hispanics

Non-Hispanic Whites

Other Races

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Results — Impact of Changes in Incidence/Relative Risk of Death from Diabetes, 1999–2050

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

45,000,000

50,000,000

1999 2004 2009 2014 2019 2024 2029 2034 2039 2044 2049

Year

Nu

mb

er

of

Pe

op

le

46 million — increasing incidence

38.7 million — decreasing RR of death from diabetes

35.5 million — baseline forecasts

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Interpreting Results (I)

Projected growth in the population would lead to forecasts of 15.8 M in 2050 v. baseline forecast of 35.5 M

0

50,000,000

100,000,000

150,000,000

200,000,000

250,000,000

300,000,000

350,000,000

400,000,000

450,000,000

1999 2004 2009 2014 2019 2024 2029 2034 2039 2044 2049

Year

Tota

l Po

pu

lati

on

334 M

273 M

396 M

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Interpreting Results (II)

Projected aging of the U.S. population + population growth would lead to 19.9 M with diabetes in 2050 as compared to baseline forecasts of 35.5 M

<45 years 45-64 yrs >64 years

2050 Age Distribution

58%22%

20%

1999 Age Distribution of Population

65%

22%

13%

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Interpreting Results (III)

Projected changes in the racial composition + age composition + population growth would lead to 22.4 M with diabetes in 2050 v. baseline forecast of 35.5 M

NHW NHB Hisp Other

1999 Racial Distribution

71%

12%

12%5%

2050 Racial Distribution

53%

13%

24%

10%

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Interpreting Results (IV)

What accounts for the rest of the growth in the number with diabetes from 1999 to 2050? Dynamic modeling approach

Prevalence is determined within the model — not assumed to remain constant over time

Projected mortality rates Increases in life expectancy mean an increase in the

number of people at risk of developing diabetes in the oldest — highest incidence — age groups

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Sensitivity Analyses

Impact of using age-, race/ethnicity-, and sex-specific incidence rates that are 20% lower than baseline rates: Projected number with diabetes in 2050 is 29.4 million 2050 forecasts are 2.7 times greater than the number

with diabetes in 1999

Impact of using age- and sex-specific relative risks of death from diabetes that are 20% higher than baseline rates: Projected number with diabetes in 2050 is 33.99 million 2050 forecasts are more than 3 times higher than the

number with diabetes in 1999

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Comparison to Previous Studies

Our forecasts suggest that 35.5 million people will have diagnosed diabetes in 2050, as compared to previous forecasts of 12 million (Helms, 1992) 29 million (Boyle et al., 2001)

Why are our forecasts higher than previous estimates? Use 1999 prevalence and incidence data Forecasts are by age (0–100 years and 101+),

race/ethnicity (NHW, NHB, Hispanic, Other) Diabetes prevalence is determined within a dynamic

model — not assumed to remain constant or follow a linear trend

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Study Limitations

Relative risk of death from diabetes Available only for adults Not available by race/ethnicity

Uncertainty about the future Population growth Diabetes incidence (assumed to remain

constant) Relative risk of death for people with diabetes

(assumed to remain constant)

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Summary and Conclusions

Forecasts suggest that the number of people with diabetes will more than triple between 1999 and 2050 Rising from 10.9 million in 1999 to 35.5 million in 2050

Diabetes prevalence is projected to grow from 4% to 9% from 1999 to 2050 Race/ethnicity-specific: Highest projected prevalence

among non-Hispanic blacks — increases from 5.6% in 1999 to 11.9% in 2050

Age-specific — Largest increase for 75+ years — from 12.8% in 1999 to over 23% in 2050

Findings suggest an increased demand for health care resources in the next 50 years to treat people with diabetes