Age-, and gender-specific incidence of vascular parkinsonism, progressive supranuclear palsy, and parkinsonian-type multiple system atrophy in North East Scotland: The PINE study

Introduction
There have been few incidence studies of vascular parkinsonism (VP), progressive supranuclear palsy (PSP), and parkinsonian-type multiple system atrophy (MSA-P). We measured the age-, gender- and socioeconomic-specific incidence rates for these conditions in north-east Scotland.

Methods
Incident non drug-induced parkinsonian patients were identified prospectively over three years by several overlapping methods from a baseline primary care population of 311,357. Parkinsonism was diagnosed if patients had two or more cardinal motor signs. Patients had yearly follow-up to improve diagnostic accuracy.

Incidence rates using the diagnosis by established research criteria at latest follow-up were calculated for each condition by age, gender, and socioeconomic status.

Results
Of 377 patients identified at baseline with possible or probable parkinsonism, 363 were confirmed as incident patients after median follow-up of 26 months (mean age 74.8 years, SD 9.8; 61% men). The crude annual incidence was 3.2 per 100,000 (95% confidence interval (CI) 2.2–4.3) for VP, 1.7 per 100,000 (95% CI 1.0–2.4) for PSP, and 1.4 per 100,000 (95% CI 0.8–2.1) for MSA-P. VP and MSA-P were more common in men (age-adjusted male to female ratios 2.58 (95% CI 1.65–3.83) and 8.65 (95% CI 4.73–14.5) respectively). Incidence did not vary with socioeconomic status.

Discussion
This is the first community-based, prospective study to report the incidence of vascular parkinsonism and the third to report the incidence of PSP and MSA-P. Further follow-up and comparison with similar studies in different populations will yield valuable prognostic and aetiological information on these conditions.