Differences in Ankylosing Spondylitis Outcomes Vary by Gender

Clinical improvements during treatment with TNF-α inhibitors was comparable between men and women with ankylosing spondylitis.

Women with ankylosing spondylitis (AS) experience worse quality of life, physical functioning, and disease activity compared with men and switch tumor necrosis factor-α (TNF-α) inhibitors more frequently, according to a study recently published in Seminars in Arthritis and Rheumatism. Both genders showed similar improvement with TNF-α inhibitors, though males had worse spinal damage at the 2-year mark.

This study included 254 participants with AS, 69% of whom were men. Higher scores on the Ankylosing Spondylitis Disease Activity Score (ASDAS), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and tender entheses were associated with female individuals, while both genders exhibited similar C-reactive protein (CRP) levels, swelling of joints, and prior extra-articular manifestations. Spinal radiographic damage was poorer among males, while quality of life and physical function were poorer among women. All clinical measures showed comparable improvement in women vs men at both 3- and 24-month assessments. Respectively, the mean 2-year ASDAS change was -1.50 vs 1.68, BASDAI was -2.7 for both, tender entheses was -2.4 vs -1.4, CRP was -8 for both, AS quality of life was -5 vs -4, and Bath Ankylosing Spondylitis Functional Index was -2.2 vs -2.1. Female individuals exhibited more frequent switching between TNF-α inhibitors in the 2-year follow-up period (32% vs 14%).

Assessments took place at baseline, 3 months, and 24 months. The study researchers defined a BASDAI of 4.0 as high disease activity; ASDAS from 1.3 to 2.0 as mild, 2.1 to 3.4 as high, and ≥3.5 as very high; and CRP levels less than 5.0 mg/L as normal. Participants were drawn from the Groningen Leeuwarden Ankylosing Spondylitis cohort. The Chi-square test, Mann Whitney U test, and independent samples T-test were used to investigate variations between males and females in terms of disease activity.

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The study researchers conclude that “after 2 years of follow-up female patients still had higher disease activity and worse quality of life and men showed larger [occiput-to-wall distance] and more radiographic damage. Importantly, although female patients switched more often between TNF-α inhibitors, short-term (3 months) and long-term (2 years) change in clinical assessments (including disease activity) was comparable between genders, except men showed more radiographic progression after 2 years than women.”

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van der Slik B, Spoorenberg A, Wink F, et al. Although female patients with ankylosing spondylitis score worse on disease activity than male patients and improvement in disease activity is comparable, male patients show more radiographic progression during treatment with TNF-α inhibitors [published online August 7, 2018]. Semin Arthritis Rheum. doi:10.1016/j.semarthrit.2018.07.015