A diagnosis of hidradenitis suppurativa may precede the development of ankylosing spondylitis, psoriatic arthritis or rheumatoid arthritis in patients, say researchers writing in the January 22 issue of JAMA Dermatology.
The findings are based on an analysis of health insurance claims data (including Medicaid and Medicare) of 70,697 patients (mean age 36.5 years) in the U.S. who were diagnosed with hidradenitis suppurativa (HS) between 2003 and 2016; and, 141,412 patients without HS.
Most patients were female (78.0% vs 52.0%) and they tended to have an increased burden of comorbidities, such as psoriasis and inflammatory bowel disease. The average follow-up period was 1.5 years.
Prior to the onset of HS, patients in both groups were arthrits free, wrote researchers in this research letter by Maria C. Schneeweiss, M.D., et al. But patients had an increased risk for developing ankylosing spondylitis compared to patiens without HS (incidence rate, 0.60 vs 0.36 per 1000; HR, 1.65 [95% CI, 1.15-2.35]); psoriatic arthritis (incidence rate, 0.84 vs 0.58 per 1000; HR, 1.44 [95% CI, 1.08-1.93]), and rheumatoid arthritis (incidence rate, 4.54 vs 3.86 per 1000; HR, 1.16 [95% CI, 1.03-1.31]).
The actual number of HS patients who went on to develop an inflammatory arthritis was low with only 2-6 cases per 10,000 patients. Although low, the data still points to an association between HS and inflammatory joint disease.
"Nevertheless, physicians treating patients with HS should be aware of symptoms suggestive of inflammatory arthritis, including morning stiffness and joint pain or swelling. This study cannot prove a causal relationship between HS and inflammatory arthritis, and further work is needed to elucidate the underlying potential shared pathogenesis of these disorders," researchers wrote.
REFERENCE: Maria C. Schneeweiss, MD; Seoyoung C. Kim, MD, ScD; Sebastian Schneeweiss, MD, ScD; et al. "Risk of Inflammatory Arthritis After a New Diagnosis of Hidradenitis Suppurativa," JAMA Dermatology. Jan. 22, 2020. DOI:10.1001/jamadermatol.2019.4590