Association between concomitant csDMARDs and clinical response to TNF inhibitors in overweight patients with axial spondyloarthritis

Background The aim of our study was to investigate the influence of conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) and body mass index (BMI) on circulating drug levels and clinical response to tumour necrosis factor inhibitor (TNFi) therapy in axial spondyloarthritis (axSpA) patients. Methods Prospective observational study during 1 year with 2 cohorts (Madrid and Amsterdam) including 180 axSpA patients treated with standard doses of infliximab or adalimumab. Patients were stratified by BMI, being 78 (43%) normal weight (18.5–24.9 kg/m 2 ) and 102 (57%) overweight/obese (≥ 25.0 kg/m 2 ). After the first year of treatment, TNFi trough levels were measured by capture ELISA. Clinical response to TNFi was defined as ∆BASDAI ≥ 2 and clinical remission as BASDAI < 2 and CRP ≤ 5 mg/L. Logistic regression models were employed to analyse the association between concomitant csDMARDs and BMI with drug levels and clinical response. Results Seventy-nine patients (44%) received concomitant csDMARDs. The administration of concomitant csDMARDs (OR 3.82; 95% CI 1.06–13.84) and being normal weight (OR 18.38; 95% CI 2.24–150.63) were independently associated with serum TNFi drug persistence. Additionally, the use of concomitant csDMARDs contributed positively to achieve clinical response (OR 7.86; 95% CI 2.39–25.78) and remission (OR 4.84; 95% CI 1.09–21.36) in overweight/obese patients, but no association was found for normal-weight patients (OR 1.10; 0.33–3.58). Conclusions The use of concomitant csDMARDs with TNFi may increase the probability of achieving clinical response in overweight/obese axSpA patients. Further research studies including larger cohorts of patients need to be done to confirm it.