In the Unites States, Parkinson disease (PD) is more common in white men than in persons in other ethnic groups, and most patients with the disease live in the Midwest and Mid-Atlantic regions, according to the results of an epidemiological study. Allison Wright Willis, MD, a neurologist at the Washington University School of Medicine in St Louis, and colleagues undertook this study because past estimates have shown inconsistent results of PD prevalence by race and region.1
Willis and her team examined Medicare data from more than 450,000 patients with PD in the United States that had been collected in 1995 and from 2000 through 2005. The prevalence, and incidence of PD were calculated according to race, sex, and county. The researchers found that the prevalence of PD (per 100,000) was 158.21 in white men, 75.57 in African Americans, and 84.95 in Asians. These results indicate a substantial variation in the prevalence of PD among races, with an approximately 50% higher prevalence of PD among white men than among African Americans and Asians. In African Americans, the prevalence ratio was lower than the incidence ratio, signifying decreased survival.
The researchers grouped counties by degree of rurality using US Census Bureau Rural Urban taxonomy. Geographic distribution was determined through the use of spatial clustering analysis. It was concluded that geographic distribution of PD was not random, with higher prevalence in the Midwest and Mid-Atlantic regions. This was not explained by rurality, although completely rural counties had higher prevalence of PD than completely urban counties.
1. Willis AW, Evanoff B, Racette B. Ethnic variation and Ggographic distribution of Parkinson disease in the United States. [P09.046] Poster Session IX: Epidemiology of Parkinson’s Disease, April 30, 2009.