OBJECTIVES : The aim of this systematic literature review was to identify cohort studies evaluating progression of Parkinson’s disease (PD) using the Hoehn and Yahr scale (H&Y), the Movement Disorder Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS), or the UPDRS.

METHODS : MEDLINE (via PubMed) and Embase were searched to identify English-language full text articles published between January 2013 and January 2018. Eligible studies were observational studies of a cohort diagnosed with PD conducted in North America or Europe that reported longitudinal data on changes in H&Y, MDS-UPDRS, or UPDRS. Studies with fewer than 50 patients or less than three years of follow-up were excluded. Specific information such as baseline characteristics, change in clinical measures over time, and interventions (i.e., levodopa equivalent dose) were extracted from each article.

RESULTS : 2,569 citations were screened and 21 longitudinal studies identified and extracted (mean sample size: 215; range: 60 to 733; mean follow-up: 4 years; range: 3 to 8). Patients with de novo PD were included in 5 studies, early PD and on medications (i.e., dopamine agonist) in 5 studies, subthalamic nucleus deep brain stimulation in 4 studies, and unspecified PD in 7 studies. UPDRS was most frequently used (20 studies), followed by H&Y (6 studies) and MDS-UPDRS (2 studies). Most studies reported UPDRS part III (motor examination; 18 studies), whilst fewer measured part I (mentation, behavior, and mood; 5 studies), part II (activities of daily living; 9 studies), or part IV (complications of therapy; 5 studies). Two studies used MDS-UPDRS in early PD, one evaluating parts I and II, and the other all four parts.

CONCLUSIONS : Most studies described the progression of motor symptoms, whereas non-motor symptoms were less studied. Although MDS-UPDRS was released in 2008 with the expectation to gradually supersede the original UPDRS, currently only two published studies have measured PD progression using the MDS-UPDRS.