Differences in Control of Cardiovascular Disease and Diabetes by Race, Ethnicity, and Education: U. S. Trends From 1999 to 2006 and Effects of Medicare Coverage

Background: Efforts to improve the care of cardiovascular disease and diabetes or expand insurance coverage for adults with these conditions may reduce differences in clinical outcomes. Objective: To assess recent national trends in disease control, trends in sociodemographic differences in control, and changes in sociodemographic differences after age 65 years associated with near-universal Medicare coverage. Design: Observational and quasi-experimental analyses of repeated cross-sectional data. Setting: National Health and Nutrition Examination Survey, 1999 to 2006. Participants: Adults age 40 to 85 years with relevant clinical conditions. Measurements: Blood pressure control (< 140/90 mm Hg) and mean systolic blood pressure among adults with hypertension (n = 4521); glycemic control (hemoglobin A(1c) levels < 7.0%) and mean hemoglobin A1c levels among those with diabetes (n = 1733); and total cholesterol level control (< 5.2 mmol/L [< 200 mg/dL]) and mean total cholesterol levels among those with coronary heart disease, stroke, or diabetes (n = 2928). Temporal trends in these measures were compared by race, ethnicity, and education, and sociodemographic differences were compared above and below eligibility for Medicare at age 65 years. Results: Disease control improved significantly between 1999 and 2006 for all 6 measures ( P < 0.001). These trends did not differ by race or ethnicity or by education ( P >= 0.185 for group-time interactions), except that white-Hispanic differences in glycemic control widened (P = 0.042). Black-white differences in systolic blood pressure were smaller among adults age 65 to 85 years than among adults age 40 to 64 years (reduction in difference, 4.2 mm Hg; P = 0.009). Black-white differences in hemoglobin A(1c) levels were also smaller after age 65 years (reduction in difference, 0.7%; P = 0.005), as were Hispanic-white differences (reduction in difference, 0.7%; P = 0.007) and differences between less and more educated adults (reduction in difference, 0.5%; P = 0.033). Limitation: Data were cross-sectional, and estimates may have been biased by coincidental events at age 65 years, such as retirement, that may affect disease control. Conclusion: Control of blood pressure and glucose and cholesterol levels has improved since 1999 for adults with cardiovascular disease and diabetes, but racial, ethnic, or socioeconomic differences have not narrowed significantly. Medicare coverage after age 65 years is associated with reductions in these differences.