Objectives: There is evidence that fat tissue may influence the response to therapy in patients with arthritis. The aim of this study was to assess whether the body mass index (BMI) affects rates of clinical remission in patients with psoriatic arthritis (PsA) treated with anti-tumour necrosis factor (TNF)-α biological drugs.
Method: We retrospectively studied 135 patients with active peripheral PsA (45 obese, 47 overweight, and 43 normal-weight). Baseline BMI was correlated with the clinical response to adalimumab, etanercept, or infliximab. After 36 months (median, range 6-79) of treatment, disease remission rates were assessed using the Disease Activity Score in 28 joints (DAS28) or the Simplified Disease Activity Index (SDAI). Possible predictors of clinical outcomes were assessed by multivariate analysis.
Results: At baseline, BMI was significantly correlated only with the Health Assessment Questionnaire (HAQ) score (r = 0.21, p = 0.02) and not with disease activity. BMI did not predict disease remission or changes in HAQ score following anti-TNF-α therapy. Obese patients showed a significantly higher HAQ score and took significantly lower doses of prednisone than normal-weight or overweight patients, but their disease remission rates on the DAS28 (37%) or the SDAI (21%) were not significantly different from those of the other two groups (44% and 21%, respectively), regardless of the TNF-α inhibitor prescribed.
Conclusions: In our retrospective analysis, disease activity and clinical response to anti-TNF-α therapy in PsA do not seem to be affected by BMI. Further prospective studies are needed to confirm these preliminary results.