Data source
We analyzed patient-level data from a de novo cohort of the Parkinson’s Progression Markers Initiative (PPMI) study - an ongoing multi-cohort observational study to identify biomarkers of Parkinson’s disease progression. The study design and its inclusion and exclusion criteria can be found at http://www.ppmi-info.org/wp-content/uploads/2017/02/PPMI-Am11-Protocol.pdf. In brief, patients in this cohort were enrolled within two years of positive diagnosis. They had not taken PD medications for more than 60 days prior to the baseline and were not expected to require PD medications for at least six months from baseline. The MDS-UPDRS observations were collected every 3 months up to 12 months and thereafter every 6 months. We used data that were available as of January 2020.
Symptomatic treatments were allowed at any time during the study. For treated subjects, both Off-Med) and On-Med MDS-UPDRS observations on the same day were recorded. To minimize the symptomatic impact of PD medications and anticipate the intended analysis in the eventual drug trials, this analysis used the Off-Med observations. The MDS-UPDRS Part III assessment included 33 items.