Parkinsonism in Ontario: increased mortality compared with controls in a large cohort study

Background — PD was associated with increased mortality before levodopa therapy became available. There have been conflicting reports of PD mortality in the modern era.

Objective — To assess current mortality rates in a large unselected population receiving treatment for parkinsonism (PKM) followed for up to 6 years.

Methods — Cases were identified using linked administrative databases, including physician service and prescription drug claims, generated in Ontario's universal health insurance system. Control subjects were identified from the provincial registry of citizens and age and sex matched to cases. Comparative mortality was evaluated over the 6-year period of the study (1993/94 to 1998/99). The sensitivity of the findings was tested with differing case definitions.

Results — In 1993, 15,304 patients with PKM were identified and were age and sex matched to 30,608 control subjects (1:2 ratio). Over the study period, 50.8% (7,779) of the cases with PKM died compared with 29.1% (8,899) of the control subjects. The cases with PKM had an overall mortality odds ratio of 2.5 (95% CI: 2.4, 2.6) compared with the control group. Results were consistent whether cases were defined by physician diagnosis, use of anti-PD drugs, or both criteria.

Conclusion — Despite modern drug therapy, PKM continues to confer a sharply increased mortality on unselected patients followed for several years.