Causes of death in a community-based study of Parkinson's disease

The aim of this community-based study of Parkinson's disease (PD) was to investigate the causes of death among PD patients over a 4-year period and to examine the quality of death certificates with regard to PD.

A total of 245 patients were diagnosed with PD on Jan 1st 1993 in a defined geographical area in Norway. This patient cohort was followed from 1993 until Dec 31st 1996. Some 84 patients died in the 4-year period of follow-up. Their death certificates were collected, and causes of death were registered. A control group with the same age and sex distribution as the decedents, from the same geographical area, were also examined for causes of death.

We found that the deceased PD patients at baseline were older, had a higher Unified Parkinson's Disease Rating Scale (UPDRS) score and Hoehn and Yahr staging than those patients who did not die during the observation period. Twice as many PD patients (20%) as controls (9%) died from pneumonia, whereas more controls than patients died from ischemic heart disease. There was a trend towards more deaths from malignant neoplasms in the control group than among PD patients. Only 56% of the death certificates of the deceased patients had PD registered as either underlying or contributing cause of death.

We found that in an unselected group of PD patients there is a significant increase in deaths from pneumonia. The low frequency of PD on deceased patients' death certificates show that research based on these certificates should be evaluated with caution.