Machine Learning Approaches to Classify Self-Reported Rheumatoid Arthritis Health Scores Using Activity Tracker Data: Longitudinal Observational Study - Kaushal Rao; William Speier; Yiwen Meng; Jinhan Wang; Nidhi Ramesh; Fenglong Xie; Yujie Su; W Benjamin Nowell; Jeffrey R Curtis; Corey Arnold (JMIR Formative Research, 2023)