Determination of county-level prostate carcinoma incidence and detection rates with Medicare claims data.
BACKGROUND: To the authors' knowledge, national-level population-based data regarding prostate carcinoma incidence and detection currently are not available. The availability of such data could identify those regions with a disproportionately high cancer incidence as well as the population-level association between prostate carcinoma detection and incidence. METHODS: Inpatient, hospital outpatient, and physician/supplier Medicare claims from 1997 were used to identify incident cases of prostate carcinoma in men age > or = 65 years and to calculate state and county-level incidence rates. The 1991 and 1997 claims data were used to determine small area rates of prostate-specific antigen (PSA) testing and prostate biopsy and to determine their correlation with incidence. RESULTS: The calculated incidence rates for 1997 were 890 per 100,000 and 1196 per 100,000, respectively, in white males and African-American males and varied substantially between counties (i.e., 25--75th percentile, 676--1124 per 100,000). Rates of PSA and prostate biopsy increased markedly from 1991 to 1997 in both white men (1580 per 100,000 to 24,286 per 100,000) and African-American men (1277 per 100,000 to 15,190 per 100,000), and considerable variation in detection between counties was observed. Counties that had higher rates of prostate biopsy also had higher age-adjusted incidence rates, and county-level PSA testing was found to be associated with incidence in African-American patients, but not in white patients. CONCLUSIONS: Medicare claims may provide an alternative source of population-based data, particularly for areas in which registry data are not readily available or are of limited scope. In addition, claims provide otherwise unavailable national data concerning cancer detection.