Are we treating women patients with real axial spondyloarthritis?

During the last years, regulatory agencies raised some relevant concerns with regard to the possibility of administrating biological therapy (BT) to non-SpA patients. Especially, the possibility of treating women with fibromyalgia as non-radiographic axSpA (nr-axSpA) was mentioned.

To evaluate if the gender distribution and clinical pattern of patients with axSpA initiating biological therapy (BT) was modified in clinical practice after its approval for non radiographic-axSpA (nr-axSpA).

Baseline dataset from a prospective ongoing cohort including all patients with axSpA treated with BT at the Rheumatology Department of University Hospital La Paz, Madrid, Spain, was analysed. Patient's characteristics and disease activity parameters were collected. Based on the approval indication date of BT for nr-axSpA, patients were classified in two periods according to the starting date for the first BT: period 1 (before 2013) and period 2 (during or after 2013). Gender distribution and disease' characteristics were compared between both groups using Chi-square and Student-t tests.

In total, 385 patients initiated BT: 266 (69%) in period 1 and 119 (31%) in period 2. No significant differences between both periods were observed regarding gender distribution (38% and 39% of women; p = 0.8). Out of those patients with nr-axSpA initiating BT in period 2, the majority (60%) were men. Women starting BT in period 2 had significantly higher systemic inflammation and mobility restriction compared with women in period 1 [median (interquartile range) CRP 10.2 mg/l (3.0-24.9) vs 3.2 mg/l (2.0-9.4); p = 0.02 and BASMI 2.7 (1.8-3.5) vs. 2.0 (1.2-2.6); p = 0.01, respectively]. In addition, they also presented significantly higher disease activity [BASDAI 6.5 (5.4-8.0) vs. 5.8 (4.6-6.8); p = 0.02; ASDAS, mean (SD) 3.6 ± 3.4 vs. 3.2 ± 1.0; p = 0.02, respectively] and more functional limitation [BASFI 5.7 (3.8-6.7) vs. 4.3 (2.0-6.1); p = 0.01, respectively] than men treated in period 2.

In our clinical practice, the frequency of women who started BT did not increase since their approval for nr-axSpA. Women treated with BT after 2012 had more objective disease activity parameters than before their approval for nr-axSpA treatment.