HRV Variation in Rheumatoid Arthritis

The goal of this observational study is to determine the association between continuous Heart Rate Variability (HRV) measured by the Oura ring and Rheumatoid Arthritis (RA) disease activity.

Inclusion Criteria: * Diagnosis of RA meeting 2010 ACR/EULAR classification criteria * Seropositive or seronegative RA eligible * Any baseline disease activity (remission/low/moderate/high) to minimize selection bias * Owns a compatible smartphone (iOS/Android) and is willing/able to use the Oura app * Willing to wear Oura Ring during sleep throughout study participation (target adherence ≥5 valid nights/week) * Willing to complete weekly remote assessments and attend baseline and three monthly routine follow-up visits * Able to read and write English language * Able to provide written informed consent Exclusion Criteria: * Atrial fibrillation or other clinically significant arrhythmias expected to invalidate HRV interpretation * Implanted pacemaker/defibrillator where HRV measurements are unreliable * Severe autonomic dysfunction likely to interfere with HRV interpretation (e.g., advanced diabetic autonomic neuropathy), per investigator judgment * Recent major cardiovascular event within 6 months (e.g., myocardial infarction) or uncontrolled heart failure (NYHA class III-IV), per investigator judgment * Current use of beta-blockers (excluded due to known autonomic/HRV effects) * Pregnancy or planned pregnancy during the study period * Inability to wear the ring reliably (e.g., occupational restrictions or hand deformity preventing wear) * Participation in another interventional clinical trial likely to confound outcomes