The 10-year Landscape of United States-Registered Parkinson Disease Clinical Trials: 2007-2016.

Abstract

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. 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. 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. 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changes. 231 (59.1%) completed trials had results published in manuscript form as of 5/1/2017, leaving 40.9% of trials unpublished. 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 About 40% of completed PD trials are unpublished, reflecting suboptimal utilization of participant efforts.