Predictors of survival in patients with Parkinson disease

OBJECTIVE: To determine the life expectancy of patients with Parkinson disease (PD) in the United States and identify demographic, geographic, and clinical factors that influence survival. DESIGN: Retrospective cohort study of 138 000 Medicare beneficiaries with incident PD who were identified in 2002 and followed up through 2008. MAIN OUTCOME MEASURES: Confounder-adjusted 6-year risk of death as influenced by 3 groups of factors: (1) race, sex, and age at diagnosis; (2) geography and environmental factors; and (3) clinical conditions. We examined hospitalization diagnoses in patients with terminal PD and compared PD mortality with that of other common diseases. RESULTS: Thirty-five percent of patients with PD lived more than 6 years. Sex and race significantly predicted survival; patients who were female (HR [hazard ratio], 0.74; 95% CI, 0.73-0.75), Hispanic (HR, 0.72; 95% CI, 0.65-0.80), or Asian (HR, 0.86; 95% CI, 0.82-0.91) had a lower adjusted risk of death than white men. Dementia, diagnosed in 69.6% of cases and most often in African American patients (78.2%) and women (71.5%), was associated with a greater likelihood of death (HR, 1.72; 95% CI, 1.69-1.75). Parkinson disease mortality was greater than that of many common life-threatening diseases. Patients with terminal PD were hospitalized frequently for cardiovascular disease (18.5%) and infection (20.9%) but rarely for PD (1.0%). Regional survival rates were similar but patients with PD living in urban high industrial metal emission areas had a slightly higher adjusted risk of death (HR, 1.19; 95% CI, 1.10-1.29). CONCLUSIONS: Demographic and clinical factors impact PD survival. Dementia is highly prevalent in patients with PD and is associated with a significant increase in mortality. More research is needed to understand whether environmental exposures influence PD course or survival