Reviewing Disease Activity Indices in Spondyloarthritis From the Sex Perspective: A Systematic Review and Metaanalysis.

Objective: To determine whether the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Ankylosing Spondylitis Disease Activity Score (ASDAS) exhibited differences between women and men.

Methods: We systematically searched MEDLINE, Embase, Web of Science, and other sources in English or Spanish from January 1, 1995, to July 31, 2020, to assess the differences according to sex in BASDAI and ASDAS. We performed a comparative analysis by sex using test and mean difference by sex metaanalyses for BASDAI and ASDAS, as well as a random-effects model using the inverse-variance method.

Results: Forty-one studies included BASDAI (6785 women, 12,929 men) and 16 of them included ASDAS (2046 women, 4403 men). Disease activity detected using BASDAI was significantly higher in women than in men (mean 4.9 vs 4.2, = 0.02), whereas ASDAS did not detect differences between sexes (mean 2.8 women vs 2.8 men). In the metaanalyses, BASDAI detected significant differences between women and men (mean difference = 0.55 [95% CI 0.46-0.65], < 0.00001), but ASDAS did not identify significant mean difference between sexes (0.04, 95% CI -0.05 to 0.12], = 0.38).

Conclusion: The 2 most widely used indices of disease activity in spondyloarthritis (SpA) discriminate differently according to sex by their different evaluations of peripheral disease. The different components and weights in BASDAI and ASDAS influence their values. BASDAI may be affected by fatigue, and in predominantly peripheral manifestations such as enthesitis, ASDAS may not be sensitive enough to detect activity. This may represent a sex bias unfavorable to women, because peripheral SpA is more common in women than in men.