Predictors of deterioration in health-related quality of life in Parkinson's disease: results from the DATATOP trial.

The aim of this study was to investigate factors associated with decline in health-related quality of life in Parkinson's disease, by a retrospective cohort study from referral centers in Canada and the United States. Subjects were patients with early Parkinson's disease (N = 362) enrolled in a clinical trial of deprenyl (selegiline) and tocopherol (DATATOP) and followed prospectively. The main outcome measure was change in health-related quality of life using SF-36 Mental and Physical Component Summary scores. The mean interval between SF-36 measurements was 1.7 +/- 0.1 years, beginning 5 to 6 years after enrolment into the trial. In multivariable analysis, baseline Hamilton Depression Scale scores and self-rated cognitive function were associated with subsequent decline in Physical Component Summary scores, while older age and Schwab and England activities of daily living scores were associated with decline in Mental Component Summary scores. The Postural Instability Gait Disorder score was the only variable found to decline concurrently with HRQOL. Our results suggest that depression, self-rated cognitive function, and one's degree of functional independence are predictors of subsequent changes in HRQOL. Our focus in clinical care needs to be broadened beyond assessing and treating Parkinsonism, recognizing the impact of mood, cognition and function on HRQOL.