Women, compared to men, have a reduced response to certain ankylosing spondylitis treatments, a study has found.
While ankylosing spondylitis has been considered a disease with male predominance, several studies have demonstrated a more balanced sex ratio in the non-radiographic form of axial spondyloarthritis (axSpA) — patients who have a clinical profile of ankylosing spondylitis, but do not exhibit radiographic inflammation of one or both of the sacroiliac joints.
Differences in ankylosing spondylitis disease characteristics between men and women include more severe spinal radiographic changes in men, while female patients have more peripheral arthritis, self-reported disease activity, and functional impairment, and a lower quality of life.
Researchers studied 440 ankylosing spondylitis patients; 249 were men and 146 were women. All patients had received TNF inhibitors (TNFi), which are anti-tumor necrosis factor (TNF) treatments that target the TNF protein, responsible for inflammation in many diseases, including ankylosing spondylitis.
After a year of treatment, researchers assessed patients’ improvement based on the Assessment of Spondyloarthritis International Society criteria (ASAS20 and ASAS40) as well as the Ankylosing Spondylitis Disease Activity Score (ASDAS).
Female patients had more peripheral disease — arthritis, inflammation of the sites where tendons insert into the bone, and inflammation of fingers or toes — at the beginning of the study. However, they also had better spinal mobility and lower mean levels of C-reactive protein, which is produced by the liver in response to inflammation.
At the beginning of the study, there were no differences between men and women in terms of disease severity (measured by the aforementioned ASAS criteria or the ASDAS) or quality of life. After a year of treatment with TNFi, more men reached a 20% improvement than women (63% vs 52%), according to the ASAS criteria.
Furthermore, more men reached an inactive disease status according to the ASDAS scoring system (26% vs 18%).
“Despite a comparable disease burden in men and women with AS at initiation of TNFi, a lower effectiveness of anti-TNF agents was found in female patients, confirming previous analyses,” researchers concluded.