Gender Differences in Axial Spondyloarthritis Save

Rheumatic conditions such as SLE and RA exhibit female predominance. In contrast, increasing evidence suggests that gender differences occur in axial spondyloarthritis in terms of time to diagnosis, clinical manifestations, treatment outcomes and quality of life. The exact mechanisms are still poorly understood. 

In abstract 1614, Dr. Poddubnyy presents the results of the PROOF study which assessed the probability of achieving inactive disease or low disease activity among males and females who were recently diagnosed with axSpA. PROOF was a 5-year, real-world, prospective, observational study conducted in 29 countries across the world. 

Patients recently diagnosed with axSpA who fulfilled the ASAS classification criteria were enrolled and further classified into radiographic (r-axSpA) or non-radiographic (nr-axSpA) according to central radiograph evaluations of sacroiliac joints. Patients included in the analysis were those who had available data at baseline and after 1 year. 

Among nr-axSpA patients, 47% were males and r-axSpA patients were predominantly males (71%) too. HLA-B27 positivity and higher CRP levels were more frequent in males for both groups. Males in the nr-axSpA (p=.0238) and r-axSpA (p=.0118) groups had higher TNF inhibitor use at baseline. In patients with r-axSpA, TNF inhibitor use increased overall and remained significantly higher among males compared to females after 1 year. 

There was noted improvement in disease activity from baseline to 1 year for males and females in both study populations but males had significantly achieved low disease activity/inactive disease than females in the nr-axSpA group. No significant differences were seen among genders in the r-axSpA. Multivariable regression analysis showed that female gender was independently associated with significantly lower odds of achieving inactive disease in nr-axSpA. This was not observed in the r-axSpA population. 

In my opinion, this study poses more questions than answers.

Why do males respond better to treatment? Does genetics play a role? How about sex hormones? Despite that, studies such as these increase the potential for further understanding of the mechanisms that contribute to the differences observed in both genders in axial spondyloarthritis. It also highlights the need for more research and robust data that can pave the way for better clinical practices and therapies.