Assessing uptake of the core outcome set in randomized controlled trials for Parkinson's disease: A systematic review

Background: Parkinson's Disease (PD) affects more than 10 million individuals, with increasing incidence worldwide. As PD's incidence rises, research funding is increasing substantially. PD's core outcome set (COS) provides standardization for PD clinical trial outcomes, improves research quality, and study comparability. Our study aimed to analyze COS uptake rate before and after the PD COS publication. Methods: We searched ClinicalTrials.gov to retrieve phase III/IV adult PD trials published between 2013 and 2023. Screening for inclusion and data extraction occurred in a masked, duplicate fashion. Trial characteristics and COS uptake rate were extracted from this sample. Results: In our 111 included trials, the COS uptake rate was highest for the 'Walking and Balance' outcome and lowest for the 'Hospital Admissions' outcome. Overall, there was a non-significant monthly increase of 0.26 % (P = 0.266, CI = [-0.20, 0.72]) in "COS-defined outcome" measurement when comparing pre- and post-COS publication. Conclusion: Our study found no significant increase in COS uptake in PD clinical trials. We found multiple outcomes to be vastly unmeasured and heterogeneity among the measurement instruments used. These findings complicate standardizing and comparing RCT outcomes. Overcoming these barriers is vital to improving the usefulness of PD research.