Recruitment bias resulted in poorer overall health status in a community-based control group.

OBJECTIVE: During a prospective community-based incidence study of parkinsonism, a control group was recruited for comparison with the incident patients. This study compared the demographic and health status of recruited vs. nonrecruited controls. STUDY DESIGN AND SETTING: For each incident patient, attempts were made to recruit an age-gender matched control from the same general practice or, failing that, from a previously identified community cohort of people aged over 64 years who had expressed an interest in taking part in future research. Recruited controls were compared with those who were approached but not recruited in terms of age, socioeconomic status, gender, several measures of health status, and survival. RESULTS: A total of 74 controls (40%) were recruited out of 186 potential controls who were approached. Recruited controls scored slightly worse than nonrecruited controls on every measure of health status, which reached statistical significance for numbers of acute prescriptions and major surgical procedures. There were no significant differences in age, gender, socioeconomic status, or survival. CONCLUSION: The control cohort was affected by recruitment bias, which suggested that recruited controls had slightly poorer health compared to nonrecruited controls. This bias may reduce differences in health when comparisons are made between the controls and the parkinsonian patients.

Changes in quality of life in people with Parkinson's disease left untreated at diagnosis.

BACKGROUND: The issue of whether to adopt a "wait and watch" strategy or to initiate drug therapy soon after diagnosis in Parkinson's disease (PD) has been the subject of some debate. A recent observational study supported early treatment by demonstrating deterioration in self-reported health status in those left untreated, but not those who received therapy. We aimed to replicate this observation. METHODS: People with PD from a prospective incidence study underwent follow-up with yearly clinical assessment of parkinsonian impairment (Unified Parkinson's Disease Rating Scale (UPDRS)) and self-reported health status (Parkinson's Disease Questionnaire (PDQ-39)). Two year outcomes were compared with those who started treatment within 1 year of diagnosis and those left untreated. RESULTS: 42 patients with PD were followed-up for 2 years, of whom 26 started treatment during the first year and 16 remained untreated. Those receiving treatment had significantly higher UPDRS and PDQ-39 scores at baseline. There was no significant deterioration in PDQ-39 score in either group (median change untreated 0.8 vs treated 4.0; p = 0.47), despite a significant difference in the change in motor UPDRS scores (untreated 6.0 vs treated -6.0; p = 0.03). CONCLUSION: Given the lack of significant deterioration in the PDQ-39 in untreated patients, we believe a "wait and watch" strategy for the treatment of newly diagnosed PD remains a credible approach unless randomised trials prove otherwise.

Screening for undiagnosed parkinsonism in people aged 65 years and over in the community.

We screened a random sample of 2449 people aged 65 years and over for undiagnosed parkinsonism, using a postal screening questionnaire followed by clinical neurological assessment. Amongst the 1556 (63.5%) patients who responded, four patients with previously undiagnosed parkinsonism were identified, suggesting a prevalence of 257 per 100,000 (95% CI 70, 658) in this age-group. Although only small, the numbers were sufficient to significantly increase the incidence of parkinsonism in an incidence study. Two simple screening questions achieved a high sensitivity for newly diagnosed parkinsonism of 95%, but a low specificity of 28%.