Outcome Measures for Parkinson's Disease Dementia: A Systematic Review

Abstract

Background: Parkinson's disease (PD) dementia (PDD) is a major cause of morbidity and mortality in PD, which severely affects patient functioning and quality of life and increases the risk for nursing home admission. Unfortunately, current treatment options for PDD are limited and have only marginal therapeutic effects. As novel treatments are developed, there will be a need to assess their efficacy in well-designed, randomized, controlled trials. However, there is no consensus on the optimal outcome measures for use in PDD clinical trials. Methods: A systematic review of PDD clinical trials and empirical studies of outcome measures used in PDD was performed. Outcome measures were divided into 5 categories: (1) cognitive; (2) behavioral and mood; (3) activities of daily living and quality of life; (4) global; and (5) caregiver burden. Findings: A total of 20 PDD pharmacological clinical trials were identified. These trials incorporated a broad array of outcome measures, which were used inconsistently across trials. We summarize the psychometric properties and other relevant data on outcome measures used, including their diagnostic utility, inter-rater reliability, test-retest reliability, responsiveness, clinically meaningful change, and availability of alternate forms. Conclusions: We have identified the best-evidenced PDD outcome measures in each domain. Further research is needed to assess the validity, reliability, and clinically meaningful change of these measures in PDD to inform the design of future clinical trials and enhance the ability of clinicians, researchers, and policy makers to interpret study results. In addition, the development of outcome measures specific to PDD may be warranted.