Increased Risk Of Inflammatory Arthritis With Hidradenitis Suppurativa

Patients with hidradenitis suppurativa (HS) face an increased risk of developing inflammatory arthritis, according to findings from a claims database.

"We observed increased risks of developing ankylosing spondylitis, psoriatic arthritis, and rheumatoid arthritis among patients with HS when compared to those without HS," said Dr. Maria C. Schneeweiss of Brigham and Women's Hospital, Harvard Medical School, in Boston.

"This suggests a possible systematic association between HS and subsequent newly diagnosed inflammatory joint disease," she told Reuters Health by email.

HS, a condition in which small, painful lumps form under the skin, has been associated with a high prevalence of spondyloarthritis, but it remains unclear whether people with HS have an increased risk of developing inflammatory arthritis.

For their study, in JAMA Dermatology, Dr. Schneeweiss and her colleagues used longitudinal claims data from commercially insured patients. They matched more than 70,000 patients with HS and twice as many without HS. Median follow-up was 1.5 years (maximum follow-up, 11 years).

Compared with patients without HS, patients with HS had a 65% higher risk of developing ankylosing spondylitis (0.60 vs. 0.36 per 1,000), a 44% higher risk of developing psoriatic arthritis (0.84 vs. 0.58 per 1,000) and a 16% higher risk of developing rheumatoid arthritis (4.54 vs. 3.86 per 1,000) - all significant risk increases.

The risks of other spondyloarthritides were not raised.

"Although the data support a systematic association between HS and subsequent newly diagnosed inflammatory joint disease, the low incremental risk is reassuring," Dr. Schneeweiss said.

"Given the high burden of disease associated with both HS and inflammatory arthritis, physicians treating patients with HS should be aware of symptoms suggestive of inflammatory arthritis, including morning stiffness (and) joint pain/swelling, and consider referral to a rheumatologist as appropriate," she said.

Dr. Schneeweiss added, "HS with comorbid inflammatory arthritis might benefit from different approaches to therapy that would address both components of disease (e.g., choosing a TNF-inhibitor, which would act as an effective HS treatment as well as a treatment intervention for concurrent spondylarthritis)."

The study was partially funded by a Pfizer fellowship for dermatology-pharmacoepidemiology research.

—Will Boggs MD

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