Racial differences in the diagnosis of Parkinson's disease.

The objective of this cohort study was to determine the incidence of Parkinson's disease (PD) and the effects of race/ethnicity, other demographic characteristics, geography, and healthcare utilization on probability of diagnosis. The authors used the Pennsylvania state Medicaid claims dataset from 1999 to 2003 to identify newly diagnosed cases of PD among the 182,271 Medicaid enrolled adults age 40-65; 319 incident cases of PD were identified. The 4-year cumulative incidence of PD was 45 per 100,000; 54 per 100,000 among whites, 23 per 100,000 among African-Americans and 40 per 100,000 among Latinos (P < 0.0001), corresponding to a relative risk (RR) of PD of 0.43 for African-Americans (P < 0.0001) compared with whites. After adjusting for age, sex, geography, reason for Medicaid eligibility, and average number of visits, African-Americans were still half as likely to be diagnosed with PD as whites (RR 0.45, P < 0.0001). Older age, more healthcare visits and Medicaid eligibility because of income alone also were significantly associated with PD diagnosis, while male sex was not. Observed racial differences in incidence of PD are not explained by differences in age, sex, income, insurance or healthcare utilization but still may be explained by biological differences or other factors such as education or aging beliefs. Better understanding of the complex biological and social determinants of these disparities is critical to improve PD care. (c) 2009 Movement Disorder Society.