Exploring The Determinants Of Racial & Ethnic Disparities In Total Knee Arthroplasty:

Health Insurance, Income And Assets

Amresh Hanchate, PhD

Health Care Research Unit

Boston University School of Medicine

AcademyHealth

Annual Research Meeting 2006

June 25, 2006

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Collaborators

• Arlene Ash, PhDHealth Care Research UnitBoston University School of Medicine

• Yuqing Zhang, PhD & David T. Felson, PhDClinical Epidemiology & Research TrainingBoston University School of Medicine

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Disparities in TKA by race/ethnicity

Source:Skinner, Jonathan et al (2003), “Racial, Ethnic, and Geographic Disparities in Rates of Knee Arthroplasty among Medicare Patients”, NEJM

TKA rate / 1,000 % of WhiteWomen White 5.97 100% Black 4.94 83% Hispanic 5.37 90%Men White 4.82 100% Black 1.84 38% Hispanic 3.46 72%

Table 1. Mean TKA rate per 1,000 Medicare enrollees per year(1998-2000)

• Relative to whites, TKA rates lower among blacks & Hispanics• Remarkably lower TKA rates among black men

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Affordability & TKA Disparities

Objective:

To investigate the role of indicators of affordability.

• Estimate TKA rates associated with• comprehensiveness of insurance coverage

• household income

• household assets

• After adjusting for affordability, we estimate the size of residual disparities (by race/ethnicity) in TKA

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Data

• Offers a very rich array of data covering health, demographic and economic domains

• Nationally representative of persons born in 1947 or earlier• Consists of 4 distinct birth cohorts – two of which surveyed prior to

1998 – but all pooled in 1998 and surveyed biennially with a common survey instrument

• This study starts with 19,983 persons in the 1998 survey round and follow through 2000 and 2002 rounds

• Final sample of 18,376 after excluding 1,597 persons who• had prior (pre-1998) history of TKA• were not White (non-Hispanic) / Black (non-Hispanic) / Hispanic• had incomplete covariate data

Health & Retirement StudyInstitute of Social Research, University of Michigan

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Measures

Outcome:Binary (1/0) indicator of whether respondent had first TKA,

because of arthritis, in the survey period• Each round respond to: Have you had a TKA in the last two years?• Maximum of 3 records per person (6 years of total exposure)• If TKA reported then subsequent rounds excluded• If death after 1998 then subsequent rounds excluded

Affordability indicators–Health insurance:

1) No insurance 2) Private 3) Medicaid4) Medicare FFS only 5) Medicare FFS + private 6) Medicare HMO7) Medicare + Medicaid

–Household Income (1993 $)

–Non-housing assets (1993 $)

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Other CovariatesAdjust for differences in need as in Dunlop et al (2003, Medical Care)

• Demographics– Gender, age, education, race & ethnicity

• Health conditions– Ever had

• 1) Heart disease, 2) lung disease, 3) cancer, 4) hypertension, 5) diabetes

– Whether has difficulty in • 1) walking one block, 2) getting up from a chair, 3) climbing one flight of

stairs, 4) stooping or crouching

• Geographic regions (10)

EstimationLogistic Random Effects Regression

• Lagged (one-period) covariates • Sampling weights used to adjust for over-sampling of non-whites

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# Persons # Observations# persons with TKA in study

periodWomen White, Non-Hispanic 7,997 18,499 247 Black, Non-Hispanic 1,586 3,645 46 Hispanic 796 1,824 17Men White, Non-Hispanic 6,405 14,785 167 Black, Non-Hispanic 983 2,205 10 Hispanic 609 1,378 7Total 18,376 42,336 494

(Health & Retirement Study, 1998-2002)

Table 2. Study Sample & TKA Counts

• Average of 2.2 records per person – same across all race & ethnicity groups – about 4.5 years of exposure period• 44% of observations are for ages 64 or younger• 32% of TKAs at age 64 or younger

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Table 3. Unadjusted & Adjusted TKA Rates & Odds Ratios (OR)

Mean rate /1,000 persons

/yearOR relative

to whiteOR relative

to white95% CI

OR relative to

white95% CI

WomenWhite 6.5 1.00 1.00 - 1.00 -Black 6.9 1.06 0.80 [0.56, 1.15] 0.96 [0.66, 1.40]Hispanic 4.5 0.68 0.69 [0.40, 1.18] 0.96 [0.55, 1.68]

MenWhite 5.4 1.00 1.00 - 1.00 -Black 2.1 0.38 0.32 [0.15, 0.66] 0.39 [0.19, 0.81]Hispanic 2.4 0.44 0.49 [0.22, 1.06] 0.64 [0.29, 1.42]

Adjusted also for Affordability Indicators

(Health & Retirement Study, 1998-2002)

UnadjustedAdjusted for

Demographics + Health Status

• Compared to whites, TKA rates are lower among Hispanics and black men• Higher rate among black women – most of this occurs when 64 or younger• Adjusting for need based on health status increases rate-gap among blacks & marginally reduces rate-gap among Hispanics• Further adjusting for affordability indicators significantly rate-gap among blacks and Hispanics – large gaps remain for non-white men

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Table 4. Affordability Indicators & TKA Odds Ratio (OR)

• Among 65+, compared to those with Medicare FFS only, probability of TKA among those with more comprehensive coverage it is at least 32% higher• Among 64 or younger, probability of TKA almost 30% lower among insured compared to those insured• Lower income/assets, lower TKA probability

Affordability Indicator OR 95% CIHealth insurance access (%) Medicare FFS Only Medicare with Private 1.30 [0.99, 1.70] Medicare with Medicaid 1.73 [1.09, 2.73] Medicare HMO Only 1.49 [1.05, 2.10] Private 1.01 [0.66, 1.55] Uninsured 0.71 [0.41, 1.22] Medicaid only 1.41 [0.90, 2.20]Household income < $10k 0.73 [0.54, 0.98] $10k - 20k 0.78 [0.62, 0.98] $20k+Household assets < $5k 0.72 [0.54, 0.96] $5k - 20k 0.88 [0.67, 1.15] $20k+ Reference

(Health & Retirement Study, 1998-2002)

Reference

Reference

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Table 5. Affordability Indicators by Race & Ethnicity

% with no insurance

among under 65

% with Medicare FFS only among over-65

% with income <

$10k

% with assets <

$5k

WomenWhite 18 36 17 16Black 19 36 49 58Hispanic 37 25 52 57

MenWhite 14 33 9 11Black 16 34 31 44Hispanic 33 26 42 47

(Health & Retirement Study, 1998-2002)

• Among 64 or younger, uninsured % for Hispanics double that for whites• But among 65+, larger % of Hispanics have comprehensive coverage• Higher % blacks and Hispanics with low income & assets

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Conclusions

• Adjusting for need, blacks and Hispanics have significantly lower TKA rates compared to whites

• Among women, adjusting for affordability indicators leaves no residual TKA disparities

• Among men, a large gap remains even after adjusting for affordability indicators – particularly among black men

• Limitations– Some loss of accuracy – recall data– Some loss of representativeness - attrition due to loss to follow up– Absence of data on out-of-pocket expenditures and more detailed

clinical information on need for TKA