Although evidence suggests that hidradenitis suppurativa (HS) appears to be associated with an increased risk of spondyloarthritis, the population-based risk of developing inflammatory arthritis among patients with HS remains unclear, explains Mia Schneeweiss, MD. To better understand the risk of developing inflammatory arthritis in this patient population, Dr. Schneeweiss and colleagues conducted a cohort study –published in JAMA Dermatology—with the hope that increasing the evidence base for arthritis comorbidities may help inform treatment options and approach for patients with HS.

The research team completed a propensity score-matched follow-up study using insurance claims to examine patient risk of developing inflammatory arthritis in patients diagnosed with HS compared with matched controls without HS. Data was gathered between 2003 and2016. Primary observed outcomes were diagnosis of inflammatory arthritis, including ankylosing spondylitis, other spondyloarthritis, psoriatic arthritis, and rheumatoid arthritis. The mean follow-up was 535 days.

The team observed increased risks of developing ankylosing spondylitis (0.6 vs. 0.4 per 1,000; hazard ratio [HR], 1.65), psoriatic arthritis (0.8 vs. 0.6 per 1,000; HR, 1.44), and rheumatoid arthritis (4.5 vs. 3.9 per 1,000; HR, 1.16) among patients with HS compared with controls. However, the data did not indicate an increased risk of “other spondyloarthritis” (3.1 vs. 3.0 per 1,000; HR, 1.02). “Generally, the incidence of arthritis was low, resulting in only two to six additional cases per 10,000 patients with during 1.5 years,” explains Dr. Schneeweiss.

“Although the data support a systematic relationship between HS and subsequent newly diagnosed inflammatory joint disease, the low incremental risk of inflammatory arthritis in patients with HS is reassuring,” notes Dr. Schneeweiss. “Nevertheless, given the high burden associated with both HS and inflammatory arthritis, physicians treating patients with HS should be aware of symptoms suggestive of inflammatory arthritis (ie, morning stiffness, joint pain, or swelling).”

Dr. Schneeweiss believes patients with HS with comorbid inflammatory arthritis could benefit from different approaches to therapy that would address both components of the disease, which would require more research. “This study is a starting point; it did not prove a causal relationship between HS and inflammatory arthritis,” she adds. “Further research is needed to elucidate the underlying potentially shared pathogenesis of these disorders.”


Risk of Inflammatory Arthritis After a New Diagnosis of Hidradenitis Suppurativa