Predictors of functional dependency in Parkinson's disease

Abstract

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.

Keywords: Parkinson's disease; dependency; predictors; prognosis.

Figure 1

Flowchart of participation in the Parkinsonism Incidence in North‐East Scotland study. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

Figure 2

Kaplan–Meier probabilities of remaining independent with dependency defined in (A) by the Schwab & England scale and (B) by the Barthel Index. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]