The association of body mass index with disease activity and clinical response to combination therapy in patients with rheumatoid arthritis.

Background: The role of obesity in clinical curse of rheumatoid arthritis (RA) is not clear. We investigated the association of obesity and adiposity with disease activity and clinical response to combination therapy in RA patients.
Materials and Methods: Active RA patients with the disease activity score using 28 joint counts (DAS28) > 2.6 were studied. Height, weight, and waist and hip circumferences were measured and body mass index (BMI) and waist to hip ratio were calculated. Patients were treated with methotrexate (7.5 to 10 mg/week) plus hydroxychloroquine (200 to 400 mg/day) and prednisolone (2.5 to 10 mg/day) and were followed by DAS28 for up to 24 weeks.
Results: One hundred and six patients were studied; age = 48.5 ± 13.8 years, 87.7% female, disease duration = 4.4 years [SE = 0.48]. DAS28 was decreased from 4.5 ± 1.6 to 2.9 ± 1.4 (P < 0.001) after 24 weeks of treatment. Only in patients with disease duration of ≤2 years, BMI (r = -0.415, P = 0.005) and waist circumference (r = -0.296, P = 0.05) were correlated with baseline DAS28. Although BMI (r = -0.337, P = 0.025) and waist circumference (r = -0.315, P = 0.038) were correlated with change in DAS28 after therapy, these correlations were disappeared after controlling for baseline DAS28.
Conclusion: Obesity and adiposity are associated with less severe disease activity in early stage of RA, but are not associated with response to combination therapy with methotrexate plus hydroxychloroquine in RA patients.