Objective:

To characterize the longitudinal motor progression of Parkinson’s disease (PD) over 104 weeks both in practically defined on and off medication states using a smartphone-based mobile application.

Background:

A critical requirement for these digital health technologies is the ability to independently track the underlying disease progression and the symptomatic response to L-DOPA therapy through frequent at-home testing.

Method:

For this analysis, we used data from the L-DOPA subgroup of the placebo arm of the Phase IIb PADOVA study (NCT04777331) in individuals with early-stage PD. Participants utilized the Roche PD Mobile Application to perform active motor tests, summarized in the following scores:  Bradykinesia Summary Score (BSS), Postural Tremor Total Tremor Power (PT), Rest Tremor Total Tremor Power (RT), and a Simple Sum Score capturing different domains (bradykinesia, tremor, speech) (SSSv1.2). Assessments were classified into on or practically defined off medication state based on the timing of the last L-DOPA dose. Longitudinal trajectories were estimated using Generalized Additive Mixed Models (GAMM) to calculate change from baseline.

Results:

Over the course of two years, participants on stable L-DOPA voluntarily collected 40% of digital data off medication. Analyses identified groups performing assessments in the off state (N=68) and the on state (N=137). Numerical decline from baseline was observed in both states across several digital scores at 104 weeks, with consistently less progression in data collected in the on state:

BSS: ON 0.40 [0.27, 0.53] vs. OFF 0.58 [0.41, 0.75]: 31% relative difference (RD)  

PT: ON 0.23 [0.02, 0.44] vs. OFF 0.47 [0.082, 0.85]: 51% RD

RT: ON 0.36 [0.068, 0.66] vs. OFF 0.44 [-0.054, 0.92]: 18% RD

SSSv1.2: ON 1.3 [-0.27, 2.8] vs. OFF 3.4 [1.4, 5.4]: 62% RD

Conclusion:

These results suggest that standardized, remote “off” medication state testing at home may be achievable in individuals with early-stage PD. Moreover, the present findings replicate differences reported for MDS-UPDRS Part III progression in the on and practically defined off states in PPMI [1], and demonstrate that digital motor testing measures known impact of L-DOPA alongside underlying disease worsening. Understanding the differences in digital motor score progression enables future informed study design decisions.

References: [1] Simuni, T. et al. (2018), Longitudinal Change of Clinical and Biological Measures in Early Parkinson’s Disease: Parkinson’s Progression Markers Initiative Cohort. Mov Disord., 33: 771-782.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/characterizing-longitudinal-motor-progression-in-parkinsons-disease-leveraging-digital-health-technologies-in-l-dopa-on-and-off-states/