Geographic Variation in Diagnosis Frequency and Risk of Death Among Medicare Beneficiaries

CONTEXT: Because diagnosis is typically thought of as purely a patient attribute, it is considered a critical factor in risk-adjustment policies designed to reward efficient and high-quality care. OBJECTIVE: To determine the association between frequency of diagnoses for chronic conditions in geographic areas and case-fatality rate among Medicare beneficiaries. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional analysis of the mean number of 9 serious chronic conditions (cancer, chronic obstructive pulmonary disease, coronary artery disease, congestive heart failure, peripheral artery disease, severe liver disease, diabetes with end-organ disease, chronic renal failure, and dementia) diagnosed in 306 hospital referral regions (HRRs) in the United States; HRRs were divided into quintiles of diagnosis frequency. Participants were 5, 153, 877 fee-for-service Medicare beneficiaries in 2007. MAIN OUTCOME MEASURES: Age/sex/race-adjusted case-fatality rates. RESULTS: Diagnosis frequency ranged across HRRs from 0. 58 chronic conditions in Grand Junction, Colorado, to 1. 23 in Miami, Florida (mean, 0. 90 95% confidence interval CI, 0. 89-0. 91; median, 0. 87 interquartile range, 0. 80-0. 96). The number of conditions diagnosed was related to risk of death: among patients diagnosed with 0, 1, 2, and 3 conditions the case-fatality rate was 16, 45, 93, and 154 per 1000, respectively. As regional diagnosis frequency increased, however, the case fatality associated with a chronic condition became progressively less. Among patients diagnosed with 1 condition, the case-fatality rate decreased in a stepwise fashion across quintiles of diagnosis frequency, from 51 per 1000 in the lowest quintile to 38 per 1000 in the highest quintile (relative rate, 0. 74 95% CI, 0. 72-0. 76). For patients diagnosed with 3 conditions, the corresponding case-fatality rates were 168 and 137 per 1000 (relative rate, 0. 81 95% CI, 0. 79-0. 84). CONCLUSION: Among fee-for-service Medicare beneficiaries, there is an inverse relationship between the regional frequency of diagnoses and the case-fatality rate for chronic conditions.