1. 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

2. 2 Collaborators Arlene Ash, PhD Health Care Research Unit Boston University School of Medicine Yuqing Zhang, PhD & David T. Felson, PhD Clinical Epidemiology & Research Training Boston University School of Medicine

3. 3 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 Relative to whites, TKA rates lower among blacks & Hispanics Remarkably lower TKA rates among black men

4. 4 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

5. 5 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 Study Institute of Social Research, University of Michigan

6. 6 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) Private3) Medicaid 4) Medicare FFS only5) Medicare FFS + private6) Medicare HMO 7) Medicare + Medicaid –Household Income (1993 $) –Non-housing assets (1993 $)

7. 7 Other Covariates Adjust 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) Estimation Logistic Random Effects Regression Lagged (one-period) covariates Sampling weights used to adjust for over-sampling of non-whites

8. 8 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

9. 9 Table 3. Unadjusted & Adjusted TKA Rates & Odds Ratios (OR) 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

10. 10 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

11. 11 Table 5. Affordability Indicators by Race & Ethnicity 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

12. 12 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