Nonradiographic Axial Spondyloarthritis Differs in Men and Women

Women with nonradiographic axial spondyloarthritis (nraxSpA) appear to have a condition distinct not only from ankylosing spondylitis (AS) by the modified New York criteria but also from nraxSpA in men, according to a study published online in RMD Open.

“Axial spondyloarthritis (axSpA) comprises both radiographic and nonradiographic disease,” wrote researchers. “However, the paucity of specific objective measures for the disease and current classification criteria showing suboptimal specificity contribute to disease heterogeneity observed in clinical practice and research.”

For the study, researchers investigated areas of heterogeneity in a cohort of 363 patients with axSpA recruited from membership in the Swiss Ankylosing Spondylitis Patient Society.

Patients underwent radiography of the sacroiliac joints and were grouped by New York criteria (AS or nraxSpA) and HLA-B27 status.

Study findings showed differences in the areas of sex, HLA-B27, and polygenic risk score, researchers reported. The male-to-female ratio was 3:1 for AS by the New York criteria but 1:1 for nraxSpA. The male-to-female ratio was 2.5:1 for HLA-27-positive AS but about 1:1 for HLA-B27-negative disease.

Women with nraxSpA had a much lower average polygenic risk score and lower HLA-B27 prevalence compared with men with nraxSpA—and compared with men and women with AS per modified New York criteria.

Polygenic risk scores differentiated male patients with nraxSpA from healthy first-degree relatives but not female patients from first-degree relatives. The study also found a strong association between radiographic sacroiliitis and HLA-B27, most notably in men.

“In conclusion, given the demonstrated heterogeneity of axSpA, clinical studies such as clinical trials should take genetics, sex, and structural damage (radiographic sacroiliitis) into consideration…” researchers wrote. “This heterogeneity also needs to be considered in clinical assessment and management of patients with axSpA. One size does not fit all.”

Reference:
Li Z, van der Linden SM, Khan MA, et al. Heterogeneity of axial spondyloarthritis: genetics, sex and structural damage matter. RMD Open. 2022;8(1):e002302. doi:10.1136/rmdopen-2022-002302