Comment on: Tumour necrosis factor inhibitor survival and predictors of response in axial spondyloarthritis—findings from a United Kingdom cohort: reply

SIR, We thank Al Arashi et al. [1] for their interest and comments on our recent report on tumour necrosis factor inhibitor (TNFi) survival and predictors of response in axial spondyloarthritis—findings from a United Kingdom cohort [2]. We did not focus specifically on sex differences in our analysis but have now undertaken further analyses on sex differences in our study population. We found a higher prevalence of acute anterior uveitis (44.9 vs 33.9%, P1⁄40.03) and family history of SpA (45.2 vs 30.4%, P1⁄4 0.02) in females, but not for IBD (females 16.8% vs males 11.9%, P1⁄40.19) or psoriasis (females 24.3% vs males 19.5%, P1⁄4 0.29). This is similar to previous studies, which reported that women are more affected by uveitis in SpA [3] and AS [4]. In our cohort, BASDAI50 response 3–6 months after initiation of index TNFi was achieved by 56 (58.3%) females and 219 (61.5%) males (P1⁄40.64). Discontinuation rates for index TNFi were higher in females (females n1⁄456, 37.3%; males n1⁄4 168, 33.5%). In addition, females had higher rates of adverse events (44.6 vs 33.9%), and males had a slightly higher proportion of primary non-response (15.5 vs 14.3%) and secondary non-response (20.8 vs 16.1%). None of these differences reached statistical significance. In conclusion, there are differences between our cohort and those reported by Al Arashi et al. [1]; however, sample sizes are small. Larger prospective studies are required to evaluate sex differences in axSpA.