Geographical difference in Parkinson's disease prevalence within West Scotland.

The wide range in reported prevalence of Parkinson's disease (PD) in the United Kingdom (between 108 and 164 per 100,000) is usually attributed to differences in study methodology. We report prevalence of PD in four geographic areas within West Scotland, which was calculated using the same methodology, from prescription database searches within primary care, combined with full case record review. Crude prevalence was 119.2 per 100,000 (95% CI 109.7-128.6) and age-adjusted prevalence was 129.5 (95% CI 119.6-139.4) in 92 General Practices covering a population of 511,927. Prevalence was significantly lower in South Glasgow (men 98.3, CI 78.7-117.9; women 83.9, CI 65.6-102.2) than South Lanarkshire (men 202.7, CI 175.0-230.4; women 151.1, CI 127.7-174.5), age-adjusted rates, both P < 0.001. Factors associated with higher prevalence of PD, such as lower cigarette smoking rates, higher education level, and rural living, were higher in South Lanarkshire than South Glasgow, but the magnitude of the difference was greater than expected considering studies describing relative risk for these factors. Access to services, and specialist clinic attendance were both higher for South Glasgow, which may influence diagnostic accuracy, time to diagnosis, and time to initiating antiparkinson therapy. Exploration of these factors is justified to explain further such wide variation in PD prevalence. (c) 2008 Movement Disorder Society.