Objective: To evaluate the association between weight loss and rheumatoid arthritis (RA) disease activity.
Methods: We conducted a retrospective cohort study of RA patients seen at routine clinic visits at an academic medical center, 2012-2015. We included patients who had ≥2 clinical disease activity index (CDAI) measures. We identified visits during follow-up where the maximum and minimum weights occurred and defined weight change and CDAI change as the differences of these measures at these visits. We defined disease activity improvement as CDAI decrease of ≥5 and clinically relevant weight loss as ≥5 kg. We performed logistic regression analyses to establish the association between improved disease activity and weight loss and baseline BMI category (≥25 kg/m2 or <25 kg/m2). We built linear regression models to investigate the association between continuous weight loss and CDAI change among patients who were overweight/obese at baseline and who lost weight during follow-up.
Results: We analyzed data from 174 RA patients with a median follow-up of 1.9 years (IQR 1.3-2.4); 117 (67%) were overweight/obese at baseline, and 53 (31%) lost ≥5 kg during follow-up. Patients who were overweight/obese and lost ≥5 kg had three-fold increased odds of disease activity improvement compared to those who did not (OR 3.03, 95%CI 1.18-7.83). Among those who were overweight/obese at baseline, each kilogram weight loss was associated with CDAI improvement of 1.15 (95%CI 0.42-1.88). Our study was limited by using clinical data from a single center without fixed intervals for assessments.
Conclusion: Clinically relevant weight loss (≥5 kg) was associated with improved RA disease activity in the routine clinical setting. Further studies are needed for replication and to evaluate the effect of prospective weight loss interventions on RA disease activity.
Keywords: disease activity; obesity; rheumatoid arthritis; weight loss.