Sex differences in treatment response in patients with rheumatoid arthritis treated with tumour necrosis factor inhibitor: a cohort study from the DANBIO registry

The aim of this study was to investigate associations between sex and treatment response and persistence in patients with rheumatoid arthritis (RA) initiating their first tumour necrosis factor inhibitor (TNFi). This Danish nationwide cohort study included RA-patients starting their first TNFi treatment between 2006 and 2022. Overall and age-specific treatment response was compared across sexes at 4 and 12 months. Treatment persistence was investigated using survival analysis. In total, 7789 RA-patients were identified; 75% were females. Females had slightly smaller ∆DAS28-CRP compared to males after 12 months, mainly due to less reduction of swollen joint count (SJC) and CRP. At 12 months the crude proportion of males with good response was higher (62%) than in females (55%), adjusted RR 1.14 (95% confidence interval (CI) 1.06; 1.23). The adjusted hazard ratio for treatment termination within first year was 0.82 (95% CI 0.73; 0.92) in males versus females. The median treatment persistence for individuals aged <50 years was 1.6 years (95% CI 1.4; 1.8) in females and 3.2 years (95% CI 2.6; 4.0) in males. The same difference was not seen in patients aged > 50 years. Despite similar baseline disease activity, females had a lower chance than males of achieving good response 4 and 12 months after starting treatment with first TNFi. The sex difference in DAS28-CRP improvement is caused by a greater decrease in CRP and SJC among males. Further, females had an increased risk of discontinuation, especially among patients aged < 50 years.