Association between hidradenitis suppurativa and spondyloarthritis.

Objectives: We aimed to investigate the existence of an association between hidrosadenitis suppurativa and spondyloarthritis.

Methods: We performed a single-centre, cross-sectional study in patients with hidrosadenitis suppurativa followed in a tertiary care center, and in healthy volunteers without dermatological disease, matched for age (±5years) and gender. For each subject included, clinical examinations, HLA-B27 testing and sacro-iliac MRI were performed in order to diagnose spondyloarthritis according to the Assessment of SpondyloArthritis international Society (ASAS) criteria.

Results: In total, 39 subjects were included in each group (70% women in each group, mean age 35.6±11.1 in the hidrosadenitis suppurativa group and 36.0±11.1 in the control group). Eleven (28.2%) patients in the hidrosadenitis suppurativa group were diagnosed with spondyloarthritis (in 4 of these, spondyloarthritis was already previously documented), and in 1 (2.6%) subject in the control group (OR 11.0; 95% CI 4.1-83.3; P=0.02). Axial spondyloarthritis was the most common form of spondyloarthritis, observed in 9/11 patients in the hidrosadenitis suppurativa group, the remainder were peripheral spondyloarthritis. In the hidrosadenitis suppurativa group, only HLA B27 was found to be associated with a diagnosis of spondyloarthritis.

Conclusions: Our results indicate that hidrosadenitis suppurativa is significantly associated with an increased risk of spondyloarthritis, independently of age and sex. Patients with hidrosadenitis suppurativa presenting osteoarticular symptoms, specially low back pain or dactylitis, should be monitored for spondyloarthritis.