Methods for Wearable-Derived Pulse Rate Measures and Their Application to Modeling the Relationship between Pulse Rate and Motor Activity in Narcolepsy Type 1.

Introduction: Narcolepsy type 1 (NT1) is a chronic, rare neurological disorder caused by loss of orexin neurons that disrupts the sleep-wake cycle. Current research suggests a link between orexin neuropeptide deficiency and heart rate regulation. Wrist-worn devices enable continuous monitoring of physiological data, including heart rate. We aim to effectively utilize wearables in clinical research by developing robust methodologies to address challenges including data artifacts and missing data. Methods: Empatica wrist-worn smartwatch data were collected for 2 weeks at baseline in the TAK-861-2001 randomized, phase 2 clinical trial (NCT05687903) from participants with NT1. Epoch-level (minute-level) pulse rate data were rigorously screened for artifacts. Daily pulse rate measures (24-h, daytime, and nighttime averages) were derived. Numerical experiments were conducted to evaluate the stability of daily measures as a function of the proportion of valid minute-level data within a given day. Mean pulse rate and motor activity daily measures and the association between the two were quantified using linear mixed-effects models. Results: Participants ( Conclusion: This work proposes a robust framework for preprocessing smartwatch pulse rate data for analyses in clinical research. The findings from our smartwatch data demonstrate a significant positive association between pulse rate and motor activity in participants with NT1 during a 2-week baseline period.