Motor and non-motor function predictors of mortality in Parkinson's disease

Doubts persist regarding the influence of Parkinson's disease (PD) on mortality. Our objective was to assess mortality rates in a prospectively followed cohort of PD patients and the impact of motor and non-motor symptoms in survival. 130 consecutive PD patients were followed during a 4-year period or until death. Baseline assessment included motor function (UPDRSIII, Hoehn and Yahr-HY), incapacity (Schwab and England-S&E, UPDRS II), Health-Related quality of life (EuroQol), non-motor symptoms (Non-Motor Symptom Scale-NMSS, MoCA, REM sleep behavior disorder symptoms questionnaire) and comorbidity burden (Charlson Comorbidity Index-CCI). These were used as predictor variables. Standardized mortality rates (SMR) were calculated, comparing with the general population. The association between mortality and predictors was tested with univariate and multivariate Cox proportional hazard regression models. Overall and gender-related SMRs were similar to the general population. SMR for pneumonia was five times higher than in the general population. Age, disease duration, CCI, EuroQol, dementia, MoCA, S&E, NMSS Hallucinations, HY, and PIGD motor phenotype were significantly associated with mortality. Adjusting for age, gender and disease duration, S&E remained significantly associated with mortality. In multivariate logistic regression analysis, death was significantly associated with disease duration, CCI and NMSS-mood/cognition scores. PD was not associated with an excess of mortality, but conferred a higher probability of dying from pneumonia. Comorbidity was a major determinant, but disease duration, baseline incapacity, cognition, psychosis, mood complaints and HRQL also contributed significantly to mortality.