High Rate of Hidradenitis Suppurativa Observed in Patients With Axial Spondyloarthritis

Among patients with axial spondyloarthritis (axSpA), there is a high prevalence of hidradenitis suppurativa (HS) compared with the general population, according to the results of a cross-sectional study published in Seminars in Arthritis and Rheumatism.

The investigators sought to determine the prevalence of HS among patients with axSpA and to identify patient characteristics associated with the presence of HS in patients with axSpA to clarify the relationship between these 2 autoinflammatory disorders. A self-screening questionnaire was sent to all participants with axSpA from the Groningen Leeuwarden Axial Spondyloarthritis cohort who met Assessment of Spondyloarthritis International Society axSpA criteria. Self-reported symptoms of HS were verified by prior medical diagnosis or confirmation by telephone using highly specific, validated questions.

Overall, 75.6% of the questionnaires qualified for analysis. Patients included in the study had a mean age of 50±13 years and 64% were men. The mean duration of symptoms among participants was 23±13 years and 79% of patients were HLA-B27-positive. A diagnosis of HS was confirmed in 41 patients with axSpA, resulting in an estimated prevalence of 9.1%, compared with an HS prevalence of 0.053% to 4.1% in the general population.

In a comparison of patients with axSpA with a positive history of HS vs those without a positive history of HS, several statistically significant differences were observed. Patients with axSpA and HS vs those with axSpA only included more women (54% vs 35%, respectively; P =.02), demonstrated significantly higher axSpA disease activity (mean Bath Ankylosing Spondylitis Disease Activity Index score, 4.5 vs 3.6, respectively; P =.01; and Ankylosing Spondylitis Disease Activity Score-C-reactive protein score, 2.6 vs 2.2, respectively; P =.003) and had significantly worse quality of life (median Ankylosing Spondylitis Quality of Life questionnaire score, 9.0 vs 4.0, respectively; P <.001).

In addition, a history of enthesitis and dactylitis was reported significantly more often among those with axSpA and HS vs those without HS (34% vs 19%, respectively; P =.03; and 15% vs 6%; P =.05). According to multivariable analysis, a higher score on the Ankylosing Spondylitis Disease Activity Score was independently associated with the presence of HS (odds ratio, 1.639; 95% CI, 1.176-2.284).

The investigators concluded that in patients with axSpA, HS is more common compared with the general population. They found that the presence of HS is associated with female gender, lower quality of life, and higher axSpA disease activity. Research should be conducted to explore the potential shared pathophysiology between axSpA and HS, and further studies are warranted to prospectively determine the prevalence and incidence of HS among patients with axSpA who are diagnosed by a dermatologist after physical examination.

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Reference

Rondags A, Arends S, Wink FR, Horváth B, Spoorenberg A. High prevalence of hidradenitis suppurativa symptoms in axial spondyloarthritis patients: a possible new extra-articular manifestation [published online March 20, 2018].  Semin Arthritis Rheum. doi: 10.1016/j.semarthrit.2018.03.010