Can real-world measures of activity, sleep, and cardiorespiratory function stratify Sjogren’s disease participants with persistent fatigue? Insights from the BRC tools study

<h2>ABSTRACT</h2><h3>Objectives</h3> Fatigue is a common and debilitating symptom for many people with Sjogren's disease (SjD). A major challenge in research with fatigue is its highly subjective nature, and unlike subjective measures of sleep and activity, no previous works have found reliable objective measures for identifying fatigue. The current analysis explored if categorising participants based on the patterns of their self-reported fatigue, rather than overall severity, would reveal more group differences in real-world measures of activity, sleep, and cardiorespiratory function estimated by digital wearables. <h3>Methods</h3> In total, 97 participants with SjD wore a VitalPatch chest-worn sensor and ActiGraph wrist-worn sensor for up to two 7-day periods while self-assessing their fatigue severity up to 4 times daily. These devices estimated 31 measures relating to activity, sleep, and cardiorespiratory function. Participants were grouped based on the persistency of their fatigue, and for comparison, a more conventional approach grouped participants based on their overall fatigue. <h3>Results</h3> Between-group differences for both approaches showed that those with more fatigue had reduced activity intensity, poorer sleep quality, and a higher heart rate. But, separating participants by fatigue persistency, compared with overall fatigue, returned more statistically significant (<i>P</i> < .05) parameters, 10 compared with 5, indicating clearer relationships when this approach is taken. <h3>Conclusions</h3> Isolating participants with higher lower-variable fatigue revealed more between-group differences than that with simply isolating those with higher overall fatigue. This alternative strategy demonstrates that digital wearables do have the potential to identify fatigue in participants with SjD. Thus, contributing towards objective, continuous estimates of fatigue in chronic diseases.