The 10‐year Landscape of United States‐Registered Parkinson Disease Clinical Trials: 2007–2016

Abstract

Background We know little about how well the goals and results of clinical trials in Parkinson disease (PD) reflect the priorities of patients and the broader PD community. Objectives We conducted a review of registered trials on http://clincialtrials.gov from 2007 to 2016 to explore whether PD trials have moved closer to the therapeutic priority goals articulated by the PD community. Methods Using the search terms: Parkinson, interventional trials, phase “0‐4,” we categorized therapeutic PD studies from http://clinicaltrials.gov between January 1, 2007 and December 31, 2016. Seven hundred and sixty‐six trials met the criteria for analysis. We explored temporal trends in the utilization of balance problems and falls; mood symptoms, including stress and anxiety; cognitive dysfunction, including dementia; and dyskinesias as primary outcomes. We analyzed trials where recruitment was listed as “completed” (n = 391) to explore publication rates. Results Balance problems and falls were listed as primary outcome measures in 125 studies (16.3%), cognitive measures in 48 (6.3%), mood features in 37 (4.8%), and dyskinesias in 30 (3.9%). Trials using balance problems and falls as a primary outcome increased in frequency per year between 2007 and 2016 (Z = ‐2.128, p = 0.033) unlike the proportion of trials evaluating cognitive dysfunction including dementia (Z = ‐0.380, p = 0.704), mood symptoms including stress and anxiety (Z = 0.345, p = 0.730), or dyskinesias (Z = 0.340, p = 0.734), which did not show temporal changes. 231 (59.1%) completed trials had results published in manuscript form as of 5/1/2017, leaving 40.9% of trials unpublished. Conclusions PD trials focusing on balance problems and falls are becoming more common. About 40% of completed PD trials are unpublished, reflecting suboptimal utilization of participant efforts.