The influence of biological sex and body mass index on the response to and duration of TNFα inhibitor treatment in patients with rheumatoid arthritis: a retrospective cohort study

Abstract

Objective: To study the association between biological sex and tumour necrosis α (TNFα) inhibitor response, to investigate the modifying effects of body mass index (BMI) on TNFα inhibitor treatment response and to study differences in drug survival and reasons to stop anti-TNFα treatment in patients with rheumatoid arthritis (RA). Method: TNFα inhibitor-naive RA patients treated with TNFα inhibitors were included in this retrospective cohort study. The primary endpoint was the difference between Disease Activity Score 28 with CRP (DAS28-CRP) at the start of TNFα inhibitor treatment and after 3-12 months (ΔDAS28-CRP). Multivariable linear regression was used to determine differences in ΔDAS28-CRP. A sub-group analysis based on BMI was done to determine effect modification of BMI on ΔDAS28-CRP. Drug survival was analysed using the log rank test. Differences in reasons to stop TNFα inhibitor treatment was analysed using chi-square. Results: A total of 203 patients, 143 females and 60 males, were included. ΔDAS28-CRP did not differ significantly between the two groups when corrected for lean body mass (LBM) (p = 0,082). This was also the case after stratification (BMI ≥ 30 kg/m2 p = 0,874; BMI < 30 kg/m2 p = 0,096). Differences in drug-survival were not significant (p = 0,236). Differences in reasons to stop anti-TNFα treatment were not significant (p = 0,116). Conclusion: Biological sex seems to not have an association of TNFα inhibitor treatment response in patients with RA. We do however see a trend towards females on average having a worse TNFα inhibitor treatment response than males. This finding can possibly be attributed to a small study population.