Daily Physical Activity Measured by a Wearable Activity Monitoring Device in Patients with Rheumatoid Arthritis

Activities of daily living in patients with rheumatoid arthritis (RA) have been evaluated by patient-reported outcomes. However, it has been difficult to measure activity intensity quantitively. Calories expended, exercise, and steps were measured quantitively by a wearable activity meter, and their associations with patients’ background characteristics were examined. Data from a prospective, observational study (CHIKARA study) were used. Eighty-five of 100 RA patients were entered and wore a wearable activity meter for 7 days. The daily calories expended and exercise for both walking and housework and steps were evaluated. Total daily calories expended and exercise was defined as the sum of walking and housework. The relationships of DAS28-ESR, mHAQ, body composition, muscle function, and general status were analyzed. The median age was 66.0 years, and the disease duration was 5.3 years. DAS28-ESR was 3.11, and mHAQ was 0.125. Total daily calories expended, exercise, and number of steps were 461.7 kcal, 3.97 METs h, and 4,788, respectively. MHAQ, walking speed, power, locomotive syndrome, and frailty were independently related to exercise. Total daily exercise and steps of the moderate and high disease activity group were significantly lower than those of the remission group. When the number of steps was < 3,333 and < 2,468, the odds ratios for locomotive syndrome and frailty increased 14.4-fold and 8.7-fold, respectively, using Fisher’s exact test (P < 0.001). Daily physical activity and number of steps were significantly decreased in RA patients with moderate and high disease activity as measured by a wearable activity meter.