A community-based study of explanatory factors for the excess risk for early renal function decline in blacks vs whites with diabetes: the Atherosclerosis Risk in Communities study.

CONTEXT: The explanation for the excess risk for diabetic renal disease in blacks is uncertain. OBJECTIVES: To compare the incidence of early renal function decline in black and white adults with diabetes and to examine possible explanatory factors for racial differences. DESIGN: Prospective cohort study. SETTING: Four US communities participating in the Atherosclerosis Risk in Communities study. PARTICIPANTS: Community-based sample of 1434 diabetic adults aged 45 to 64 years. MEASUREMENTS: Detailed baseline assessment using structured interview, results of physical examination, and laboratory measurements. MAIN OUTCOME: Development of early renal function decline defined by an increase in serum creatinine of at least 35.4 micromol/L (0.4 mg/dL) during 3 years of follow-up. RESULTS: During 3 years of follow-up, early renal function decline developed in 45 blacks (28.4 per 1000 person-years [PY]) and 25 whites (9.6 per 1000 PY). After adjustment for age, sex, and baseline serum creatinine level, early renal function decline was more than 3 times as likely to develop in blacks than whites (odds ratio, 3.15; 95% confidence interval, 1.86-5.33). Additional adjustment for education, household income, health insurance, fasting glucose level, mean systolic blood pressure, smoking history, and physical activity level reduced the relative odds in blacks to 1.38 (95% confidence interval, 0.71-2.69), corresponding to a 82% reduction in excess risk. CONCLUSIONS: These data suggest that early renal function decline is 3 times more likely to develop in blacks than whites and that potentially modifiable factors, including lower socioeconomic status, suboptimal health behaviors, and suboptimal control of glucose level and blood pressure, account for more than 80% of this disparity.

Patterns of expenditures and use of services among older adults with diabetes. Implications for the transition to capitated managed care.

OBJECTIVE: To examine health care use and expenditures among older adults with diabetes, investigate factors that are associated with higher expenditures, and describe the policy implications of caring for this population under managed care. RESEARCH DESIGN AND METHODS: A cross-sectional analysis of expenditures for individuals with diabetes over age 65 years from a nationwide 5% random sample of Medicare beneficiaries was conducted during 1992. All components of medical care covered under Medicare were examined. Multivariate analysis was used to assess the contribution of age, race, sex, number of diabetic complications, and comorbidity (Charlson Index) on total expenditures. RESULTS: On average, individuals with diabetes (n = 188,470) were 1.5 times (P < 0.0001) as expensive as all Medicare beneficiaries (n = 1,371,960). However, there were wide variations, with the most expensive 10% of beneficiaries with diabetes accounting for 56% of expenditures for individuals with diabetes and the least expensive 50% accounting for 4%. Acute care hospitalizations accounted for the majority (60%) of total expenditures, whereas outpatient and physician services accounted for 7 and 33%, respectively. There were no differences in the number of complications for all older adults with diabetes compared with those with the highest expenditures. However, the average number of hospitalizations was 1.6 times (0.53 vs. 0.34; P < 0.0001) higher, and the average length of stay was 2 days longer, among older adults with diabetes (P < 0.0001). In the regression model, age and male sex (factors currently used to set payment rates for Medicare managed care enrollees), and number of diabetic complications, but not race, were positively related to expenditures, yet had minimal predictive power (R2 = 0.0006). The addition of the Charlson Index, also positively related to expenditures, was able to explain up to 20% of the variation in total expenditures (R2 = 0.196). CONCLUSIONS: There are large variations in expenditures among older adults with diabetes. Because elderly beneficiaries with diabetes are more expensive than the average older adult, current Medicare capitation rates may be inadequate. To avoid selection bias and under-treatment of this vulnerable population under managed care, methods to construct fair payment rates and safeguard quality of care are desirable.

Predicting expenditures for Medicare beneficiaries with diabetes. A prospective cohort study from 1994 to 1996.

OBJECTIVE: To describe health care expenditures and utilization patterns among older adults with diabetes and to examine factors associated with expenditures over a 3-year period. RESEARCH DESIGN AND METHODS: We conducted a prospective cohort study of health care expenditures and utilization by diabetic patients from a random nationwide sample of aged Medicare beneficiaries from 1994 to 1996. All services covered by the Medicare program were examined. Multivariate regression was used to assess the contribution of patient characteristics in 1994 on Part B, inpatient, and total expenditures in 1995 and 1996. RESULTS: Per capita expenditures for beneficiaries with diabetes (n = 169,613) were 1.7 times greater than those for those beneficiaries without diabetes (n = 968,832) in 1994. This ratio remained fairly constant over the 2 years of follow-up. Expenditures for beneficiaries with diabetes were highly skewed. However, few of these individuals remained in the highest expenditure quintile over the 2 years of follow-up. Using multiple regression analysis to adjust for demographic and clinical characteristics, we were able to explain 7% of the variation in total expenditures in 1995 and 6% of the variation in 1996. Using the same model, we were able to explain 10.7% of the variation in Part B expenditures in 1995 and 8% in 1996. CONCLUSIONS: Beneficiaries with diabetes are consistently more expensive than beneficiaries without diabetes. Demographic and clinical factors at baseline are able to predict only a small portion of future expenditures among this population, and the most expensive patients in one year were often not the most expensive in subsequent years. More work is necessary to assure equitable risk adjustment in the calculation of capitation rates for health plans and practitioners who specialize in the care of individuals with diabetes.