Supplementary Material for: Tolerability and the Accelerome: Open-source Wrist Accelerometry Relates to Symptom Burden in Androgen Ablated Older Men with Prostate Cancer

Background: Older men on androgen suppression for prostate cancer experience substantial symptom burden that is often missed between clinic visits. In prior work from our group, frequency-domain features ranked highly for predicting geriatric impairment, motivating a focus on interpretable spectral measures from open-source wrist accelerometry.
Objective: To identify accelerometry features from a pre-specified library that track weekly symptom burden in older men on ADT, and to characterize the temporal scale of the top candidates; spectral features were of particular interest.

Methods: Retrospective secondary analysis of an open-source pilot. Ten men ≥65 years with metastatic prostate cancer completed weekly PRO-CTCAE items and self-rated health over 12 weeks. Symptom-triggered (or random) 48-h, 10-Hz wrist-accelerometry sessions were aggregated to 60-s counts-per-minute (CPM) and vector-magnitude change (VMC). From these, 98 pre-specified statistical and spectral features were extracted. Associations with a weekly Symptom-Burden + SRH composite (SBSI) were assessed using linear mixed-effects models (days + random intercept), Spearman correlations across five 30-day bins, penalized mixed-effects regression LASSO (λ=0.5, 1), and a 500-tree random forest.

Results: Nine participants provided 44 monitoring windows (14–48 h). In mixed-effects models, two CPM features were nominally associated with SBSI but did not survive false-discovery-rate adjustment. Across 30-day bins, a minute-scale restlessness pattern (CPM_top_15_freq3) rose with higher SBSI (ρ=+0.95; p=0.012), while an overall rhythm balance measure (CPM_median_freq) tended to shift lower (ρ=−0.88; p=0.049). Penalized models (λ=1) retained both features, and random-forest importance ranked them highest. Within-participant plots showed restlessness increased during higher-symptom weeks, while rhythm balance showed individual variability.

Conclusion: Two interpretable CPM spectral features—restlessness (CPM_top_15_freq3) and global rhythm balance (CPM_median_freq)—were consistently associated with weekly symptom burden in this cohort. Findings are preliminary and warrant prospective validation for remote symptom monitoring.