Survival and cause of death in a cohort of patients with parkinsonism: possible clues to aetiology?

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Abstract
Most previous studies that have examined the survival of patients with parkinsonism have recruited them from specialist centres. No previous study has ever reported cause specific mortality. We report on the mortality of a cohort of 220 parkinsonian patients recruited between 1970 and 1972 from 40 primary health care practices all over England and Wales and matched to 421 controls. At 20 years of follow up, 195 cases (88.6%) and 295 controls (70.1%) were no longer alive (P < 0.001). The median age at death for cases was 77.6 (range 53.8-97.3) and 83.5 (range 55.0-100.1) for controls (P < 0.001). The all cause hazard ratio for cases compared with controls was 2.6 (95% confidence interval (95% CI) 2.2-3.2) controlling for age, sex, and geographical region. There was little difference between men and women. Differences for cause specific mortality also emerged. Both ischemic heart disease (2.3, 95% CI 1.5-3.4) and cerebrovascular disease (3.6, 95% CI 2.2-6.1) showed significantly increased hazard ratios. Possible reasons for these findings are discussed in terms of (a) competing causes of death, (b) a secondary effect of drug treatment, and (c) common aetiological factors for both parkinsonism and cardiovascular disease.