To assess the stability of remote application of the Movement Disorder Society (MDS) prodromal Parkinson’s disease (PD) criteria and of expert determination of concern for parkinsonism in a cohort of LRRK2 G2019S carriers at high risk for PD over one year.

Remote application of the MDS prodromal PD criteria is feasible. The longitudinal stability, sensitivity and specificity of remote application has not been established.

Using the MDS prodromal PD criteria, we calculated likelihood ratios among LRRK2 carriers without PD ≥ 50 years of age enrolled in a 36-month decentralized, remote study. Those with a likelihood ratio that exceeded age-based minimum likelihood ratios necessary to meet the recommended 80% threshold were classified as having probable prodromal PD.  Movement disorders experts blinded to self-reported PD status conducted a modified MDS – Unified Parkinson Disease Rating Scale motor examination and identified cases of concern for parkinsonism.

At baseline, the prodromal PD criteria were applied in 127 of the 211 participants without PD (mean (SD) age 53.3 (15.0), 59% female, 73% Ashkenazi Jewish). Probable prodromal PD was identified in ten and concern for parkinsonism in 20.  Six participants met both conditions. At year one, six of ten (60%) with probable PD at baseline were again classified as probable PD and 14 of 20 (70%) with concern for parkinsonism remained in that category. Of the six cases where concern for parkinsonism resolved, two had essential tremor, four had potentially confounding medical conditions, and two had completed their baseline visit in a car. None were diagnosed with PD.

In a LRRK2 G2019S cohort, the identification of probable prodromal PD and concern for parkinsonism did not remain stable over one year in one-third of cases.  This may reflect fluctuation of symptoms included in the prodromal PD criteria or limitations of the remote examination.