Patients with hidradenitis suppurativa (HS) have an increased risk for developing ankylosing spondylitis, psoriatic arthritis, and rheumatoid arthritis, study research published in JAMA Dermatology suggests.

Longitudinal claims data from commercially insured patients in the United States were used to identify patients who had received a diagnosis of HS from 2003 to 2016. The date for cohort entry of the group of patients with HS was the first recorded date of HS diagnosis after ≥180 days of continuous enrollment. After 1:1 propensity score matching, there were 60,872 patients in the dataset with HS and 60,872 patients in the dataset without HS.

The investigators assessed rates of ankylosing spondylitis, psoriatic arthritis, other spondyloarthritis (reactive arthropathy, spinal enthesopathy, sacroiliitis, or unspecified inflammatory spondylopathies), and rheumatoid arthritis during follow-up in both groups. Follow-up was defined as the period between the date of cohort entry until either occurrence of inflammatory arthritis, death, disenrollment, or end of data stream.

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Before cohort entry, both patient groups were free of arthritis. During a median follow-up period of 1.5 years (interquartile range, 0.6-3.1 years), patients in the HS group had a significantly higher risk for developing ankylosing spondylitis (incidence rate, 0.60 vs 0.36 per 1000; hazard ratio [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). There was no difference in the HS and non-HS groups in terms of the risk for other spondylarthritis (incidence rate, 3.07 vs 3.00 per 1000, respectively; HR, 1.02; 95% CI, 0.89-1.17).

A study limitation was the reliance on claims data, which limited the ability to make causal conclusions about the relationship between HS and inflammatory arthritis.

Despite these limitations, the investigators suggest that “physicians treating patients with HS should be aware of symptoms suggestive of inflammatory arthritis, including morning stiffness and joint pain or swelling.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

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Reference

Schneeweiss MC, Kim SC, Schneeweiss S, Rosmarin D, Merola JF. Risk of inflammatory arthritis after a new diagnosis of hidradenitis suppurativa [published online January 22, 2020]. JAMA Dermatol. doi:10.1001/jamadermatol.2019.4590