Rotterdam study - higher incidence of PD than previously reported

In Neurology, a report from the Rotterdam study describes higher incidence rates for parkinsonism and Parkinson disease than previously reported. The authors attribute the higher rates to their intensive case-finding methods.Dr de Lau and colleagues determined the incidence rates of parkinsonism and Parkinson disease (PD) in participants in the Rotterdam study using in-person screening, plus additional information from general practitioners' and pharmacy records. The study included 6,839 Rotterdam study participants who were free of parkinsonism at baseline.The authors report, "After a mean follow-up period of 5.8 years, 132 subjects with incident parkinsonism were identified, of whom 67 (51%) had PD." Incidence rates for PD increased from 0.3 per 1,000 person-years in people aged 55 to 65 years to 4.4 per 1,000 person-years for those aged 85 years and older. The risk of developing any parkinsonism between the age of 55 and 85 years was 7.7% for women and 8.5% for men and the risk of PD was 4.2% for women and 6.1% for men. "The overall age-adjusted incidence rate of any parkinsonism was not different in men and women, but men seem to have a higher risk for PD (male-to-female ratio, 1.54; 95% CI, 0.95 to 2.51)," the authors note.Dr de Lau and colleagues note that these incidence rates are higher than most of the figures previously reported. They explain that this is most likely the result of how they identified patients with parkinsonism or PD. "We think that the high rates in our study are mainly the result of more intensive case-finding methods. Most of the previously published studies were based on existing medical records. Prevalence surveys have shown that a large proportion of patients with parkinsonism remain undiagnosed if search strategies only rely on medical records and no population screening is done." Reference...