Parkinson disease and risk of mortality: a prospective comorbidity-matched cohort study

To evaluate the association between Parkinson disease (PD) and mortality after adjustment for comorbidities.

We conducted a matched cohort analysis among 22,071 participants in the Physicians' Health Study. Five hundred sixty incident PD cases were identified by self-report. We used a modified Charlson Comorbidity Index to calculate a comorbidity score. Each PD case was matched by age to a comparator who was alive and had an identical comorbidity score at the time of PD diagnosis of the case. Both cohorts were followed for all-cause mortality. We used proportional hazards models to calculate hazard ratios (HRs) for mortality.

A total of 330 participants died over a median follow-up of 5.8 years, 200 (35.7%) in the PD group and 130 (23.2%) in the reference group. After adjustment for smoking and age at PD onset, the HR for mortality was 2.32 (95% CI 1.85-2.92). The mortality risk remained significant with increasing age at onset, even in those aged >or=80 years (HR = 2.10; 95% CI 1.44-3.00). The increased risk was apparent for short PD duration (<2 years) and remained stable with increasing duration. We found no different risk of mortality associated with PD according to smoking status.

In this large prospective cohort of men and after matching on comorbidities, we found that Parkinson disease patients had an increased risk of all-cause mortality. Mortality was increased regardless of disease duration, did not diminish with increasing age at onset, and was not influenced by smoking status.