Predictors of functional dependency in Parkinson's disease

BACKGROUND Functional dependency, the need for help in basic activities of daily living, is an important patient-oriented outcome. We aimed to describe the development of dependency in Parkinson's disease (PD) and identify independent prognostic factors for this outcome. METHODS We analyzed data from the Parkinsonism Incidence in North-East Scotland (PINE) study, a prospective, community-based incident cohort of PD with ongoing follow-up. We described the development of dependency defined by a Schwab & England score of < 80% and a Barthel Index of <19. We identified the baseline predictors of dependency using multivariable Cox regression. RESULTS In 198 patients with PD, the rate of development of dependency was 14 per 100 person years. Older age at diagnosis (hazard ratio for 10-year increase 2.23 [95% confidence interval 1.66-2.98]), greater smoking history (hazard ratio for 10-pack-year increase, 1.15 [1.04-1.26]), more severe axial impairment (hazard ratio for 5-point increase in sum of axial items from UPDRS scale, 1.78 [1.30-2.44]), and lower MMSE score (hazard ratio 0.88 [0.79-0.98]) were independently associated with a higher risk of dependency as defined by Schwab & England. Only older age (hazard ratio for 10-year increase 1.35 [1.04-1.76]) and severity of axial impairment (hazard ratio for 5-point increase 1.85 [1.31-2.62]) were associated with a higher risk of dependency as defined by the Barthel Index. Sex, deprivation, comorbidity, overall UPDRS motor score, and disease stage were not independently associated with dependency. CONCLUSION This is the first community-based study of dependency in PD. There was a high rate of dependency development. Older age, more smoking, more axial impairment, and poorer cognition were independent predictors. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.