An Exploration of the High Prevalence of Parkinson's Disease in a Rural Area of North West England.

BACKGROUND

Globally the prevalence of Idiopathic Parkinson's Disease (IPD) is rising. Increasing recognition is being given to the influence of environmental factors on this rise, although the precise impact of such factors remains poorly understood. We need accurate ways of measuring prevalence to understand regional and global trends.

OBJECTIVES

To use case finding methodology to measure the crude, and age adjusted, prevalence of IPD in a rural area of North West England, and to describe the difference in results with those obtained using electronic record searching alone to understand the accuracy of such methods. To compare prevalence between subgroups to build hypotheses that could guide further research.

METHODS

Local Parkinson's service records from several sources were searched electronically and manually reviewed against validated diagnostic criteria. Figures were age adjusted according to the national denominator population.

RESULTS

The age adjusted prevalence of IPD was 201/100,000 (95% CI 186-217), higher than in any other published UK study using similar case finding methods. Numbers were higher using electronic diagnostic code searching alone, which may over estimate prevalence. No significant difference was seen between rural and urban areas, relative risk 0.92 (95% CI 0.80-1.06), although there was a trend to higher prevalence in historically industrial coastal areas.

CONCLUSIONS

This study highlights some of the pitfalls in using large healthcare datasets to measure IPD prevalence. Overall, the prevalence of IPD is high in this predominantly rural area, and exhibits prevalence trends that warrant further investigation in relation to genetic and environmental factors.