Objective: To quantify the prevalence of prodromal phase of Parkinson’s disease (PD) defined per 2015 MDS research criteria and their potential to predict incident clinically manifest PD in the general elderly population.

Background: In 2015, the International Parkinson and Movement Disorder Society (MDS) Task Force on the Definition of PD published research criteria for the diagnosis of the prodromal phase of PD, based on a data driven probabilistic approach using a Bayesian naive classifier methodology. Probable prodromal PD was operationally defined by a post-test probability of ≥80%. These criteria have not yet been applied to population-based cohorts.

Methods: We retrospectively applied the MDS criteria for prodromal PD to participants aged 55-94 years of the 2005 examination of the longitudinal population-based Bruneck Study. The following data were available to calculate baseline posttest probabilities: 1. age for pretest probability; 2. sex, pesticide or solvent exposure, non-use of caffeine, smoking status, family history, and substantia nigra hyperechogenicity as risk markers; and 3. probable RBD, possible subthreshold parkinsonism, olfactory loss, constipation, excessive daytime somnolence, symptomatic hypotension, urinary dysfunction, and depression as prodromal markers. Presence of clinically defined motor PD was ascertained per United Kingdom PD Society Brain Bank criteria at baseline and, to identify de-novo cases of incident motor PD, at 3- and 5-year follow-up visits.

Results: Of the 574 participants in the 2005 assessment, 17 had secondary parkinsonism and 18 had motor PD and were excluded from further analysis. In the remaining 539 participants the median post-test probability for prodromal PD was 2.4% (25th–75th percentile, 0.6–8.7). The prevalence of probable prodromal PD was 2.2% (95%CI, 1.2–3.9). Of the 488 participants undergoing at least on follow-up visit, 11 participants were diagnosed with incident motor PD. Sensitivity of baseline probable prodromal PD status for incident PD over 5 years was 54.6% (95%CI, 28.0–78.8), specificity was 99.2% (97.8–99.8), PPV was 60.0% (31.2–83.3), and NPV was 99.0% (97.5–99.6).

Conclusions: Our findings suggest that the MDS research criteria are a promising tool to identify individuals who will go on to develop motor PD over 5 years with a high specificity and positive predictivity in the general population.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/application-of-the-mds-research-criteria-for-prodromal-parkinsons-disease-to-the-longitudinal-population-based-bruneck-study-cohort/