Obesity is a worldwide epidemic and a growing body of evidence suggests that it may affect the body's response to biologic agents. We investigated the influence of obesity on the efficacy of different biologic agents used to treat inflammatory diseases.

Medline, EMBASE and the Cochrane Database were searched using relevant MeSH and keyword terms for obesity and bDMARDs. Articles were selected if they reported a clinical response in obese subjects relative to other BMI categories. Response and remission outcomes were assessed using meta-analysis and all other reported outcomes were summarized.

Among the 3850 records retrieved, 24 articles met the inclusion criteria, including 10 on rheumatoid arthritis (RA), 4 on axial spondyloarthritis (axSpA), 4 on Crohn's disease (CD), 4 on psoriasis (Ps) and 2 on psoriasic arthritis (PsA). Four biological disease-modifying anti-rheumatic drugs (bDMARDs) – anti-TNF agents, T cell co-stimulation inhibitor (abatacept), IL-6 inhibitor (tocilizumab), and B-cell depletion therapy (rituximab) – were involved. The meta-analysis showed that the odds to reach a good response or achieve remission were lower in obese (BMI>30kg/m²) than non-obese (BMI≤30kg/m²) patients who were treated with anti-TNF agents (good responder % in RA: OR 0.34, 95% CI 0.18–0.64; remission% in RA: OR 0.36, 95% CI 0.21–0.59; BASDAI50% in axSpA: OR 0.41, 95% CI 0.21–0.83), but no significant difference between obese and non-obese was found in patients treated with abatacept (good responder % in RA: OR 0.75, 95% CI 0.42–1.36; remission% in RA: OR 0.84, 95% CI 0.65–1.09) and tocilizumab (good responder % in RA: OR 1.08, 95% CI 0.44–2.63; remission% in RA: OR 0.91, 95% CI 0.50–1.66).

Obesity hampered the effect of anti-TNF agents, but not those of abatacept and tocilizumab, suggesting that a personalized treatment strategy should be considered for obese patients with inflammatory diseases.