Objective: Investigate the measurement properties of exploratory sensor-derived measures (SDMs) from a smartphone-based typing test in the LUMA study of BIIB122/DNL151 for Parkinson’s disease (PD).

Background: Typing is a critical everyday function that relies on fine motor control but is not directly assessed in the MDS-UPDRS. Keystroke dynamics during smartphone typing can capture motor and nonmotor function as an activity of daily living in PD. A smartphone application (Konectom, Indivi AG), including an active typing task (Copying Words), is used as an exploratory outcome in LUMA.

Method: Treatment-blinded longitudinal data from 78 selected trial participants (baseline age, 61.7±8.9 years; MDS-UPDRS, 19.3±7.7) were analyzed. Data included 48 weeks of weekly remote administration of Copying Words, where participants typed as many prompted words on the screen as possible for 60 seconds. Four SDMs, shown to be reliable at baseline and have discriminant and construct validity compared with clinical anchors, were investigated: Number of Correct Words, Reaction Time at word initiation (median), and Letter Interval (median and fastest [5th centile]). Reliability was assessed in two 4-week windows, over weeks 23 to 26 (intraclass correlation coefficient ICC_w24 and standardized minimum detectable change MDC95%_w24) and 45 to 48 (ICC_w48, MDC95%_w48). SDM longitudinal responsiveness was quantified as the standardized response mean (SRM; change from baseline divided by its SD) at weeks 36 and 48. SRM was also calculated for the MDS-UPDRS part III hand scores (mean of MDS-UPDRS 3.4, 3.5, and 3.6 for both hands [UPDRS3-Hand]).

Results: Reliability was high across study periods (SDM ranges: ICC_w24, 0.83-0.93; MDC95%_w24, 17%-21%; ICC_w48, 0.75-0.90; MDC95%_w48, 18%-23%). The fastest Letter Interval was the most promising measure, having greater SRM than UPDRS3-Hand both at weeks 36 (0.27 vs. 0.14) and 48 (0.44 vs. 0.24).

Conclusion: In LUMA, a smartphone-based typing test provided longitudinally reliable SDMs capturing multiple dimensions of keystroke dynamics. Among these, the fastest Letter Interval showed a favorable responsiveness compared with UPDRS3-Hand scores over 48 weeks, suggesting a potential higher sensitivity to detect change in this functional domain. This exploratory outcome may complement other assessments in LUMA.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/responsiveness-of-sensor-derived-measures-from-a-smartphone-based-active-typing-test-in-the-phase-2b-luma-study-of-parkinsons-disease/