Obese patients with rheumatoid arthritis (RA) report more joint swelling and tenderness and often have poorer responses to therapy than nonobese patients. The aim of this posthoc analysis of the MUSICA trial was to compare imaging and clinical disease activity measures in obese and nonobese patients with RA.
MUSICA evaluated methotrexate (MTX) 20 mg/week versus 7.5 mg/week in combination with adalimumab (ADA) in RA patients with an inadequate response to MTX. Patients were categorized by baseline body mass index as normal (< 25), overweight (≥ 25 to < 30), or obese (≥ 30). Synovial vascularity and hypertrophy, swollen and tender joint counts (SJC and TJC), American College of Rheumatology (ACR) responses, and low disease activity (LDA), defined as Clinical Disease Activity Index < 10 and 28-joint count Disease Activity Score using C-reactive protein (DAS28-CRP) < 3.2, were assessed at weeks 12 and 24.
Patient characteristics were similar among groups at baseline. Obese patients had numerically smaller changes from baseline to weeks 12/24 in SJC, TJC, DAS28-CRP, and synovial hypertrophy and vascularity versus nonobese patients. Significantly fewer obese patients reached ACR20/50 at weeks 12 and 24, and LDA at Week 12; this difference was especially apparent in patients receiving 7.5 mg/week MTX but was no longer significant at Week 24.
Obese patients with RA had worse clinical and ultrasonographic responses than nonobese patients, which were partly overcome with time. Obese patients may experience better and faster clinical improvements if ADA is initiated with high-dose (20 mg/week) rather than low-dose MTX. [ClinicalTrials.gov: NCT01185288].