Survival study of Parkinson disease in Olmsted county, Minnesota

Objective: To compare survival in incident cases of Parkinson disease (PD) with survival in subjects free of PD from the general population. Methods: We used the medical records linkage system of the Rochester Epidemiology Project to identify incident cases of PD in Olmsted County, Minnesota, for the period 1976-1995. Cases were matched by age and sex to referent subjects from the same population. For 196 cases and 185 referent subjects, we studied survival between the date of diagnosis of PD (or index date) and death, loss to follow-up, or end of the study (May 1, 2000). Results: The median length of follow-up was 7.2 years for cases and 8.0 years for referent subjects; 110 patients with PD and 79 referent subjects died during follow-up. The median survival was 10.3 years in cases and 13.4 years in referent subjects. The relative risk (RR) of death was 1.60 (95% confidence interval [CI], 1.20-2.14; P=.002) overall, 1.81 (95% CI, 1.15-2.84; P=.01) in women, and 1.49 (95% Cl, 1.01-2.20; P=.04) in men. There was a decreasing trend in the RR of death according to age at onset of PD (in tertiles): younger than 67 years, RR, 2.04 (95% CI, 0.99-4.19; P=.05); 67 to 76 years, RR, 1.76 (95% CI, 1.08-2.86; P=.02); and older than 76 years, RR, 1.48 (95% CI, 0.95-2.29; P=.08). Patients with PD who had both rest tremor and pronounced asymmetry had a better prognosis than patients with neither clinical characteristic. Patients with PD who smoked survived better than expected. Conclusions: Patients with PD face a higher risk of death compared with subjects free of PD from the general population. Certain clinical characteristics and smoking modify survival.