In this study, obese and underweight patients with rheumatoid arthritis exhibited lower response rates, and no evidence was found for a superior impact of non-tumor-necrosis factor inhibitors (TNFi) therapy over TNFi therapy in particular body mass index (BMI) categories.

• Using data from CorEvitas, experts compared TNFi vs non-TNFi biologic therapies in rheumatoid arthritis, and investigated if BMI altered the impact of each therapy.

• This study included 2,891 TNFi and 3,010 non-TNFi initiators.

• Lower odds of achieving low disease activity or minimal clinically important difference and less improvement in Clinical Disease Activity Index were observed in initiators with severe obesity, although links were attenuated with adjustment.

• Low BMI was found to be linked with decreased response rates in adjusted models including lower odds of low disease activity [OR (95% CI): 0.32 (0.15,0.71)].

• In analyses stratified by TNFi and non-TNFi therapies, clinical response rates did not differ for TNFi vs non-TNFi across BMI categories.

• Estimates for non-TNFi biologics fit within the 95% CI for TNFi.