Hidradenitis suppurativa bidirectionally linked to atopic dermatitis

A recent study has found a two-way association between hidradenitis suppurativa (HS) and atopic dermatitis (AD), warning dermatologists to be aware of this relationship.

“The coexistence of HS and AD had been reported but, to our knowledge, was not investigated in controlled studies,” the authors said.

To address this gap in research, the authors conducted this population-based retrospective cohort study and compared the incidence rate of AD among patients with HS (n=6,779) and age-, sex-, and ethnicity-matched control individuals (n=33,260). They also estimated adjusted hazard ratios (HRs) and adjusted odds ratios (ORs).

AD incidence was 2.51 (95 percent confidence interval [CI], 2.07–3.02) per 1,000 person-years among HS patients and 1.24 (95 percent CI, 1.10–1.40) per 1,000 person-years among control participants. Patients with HS had a twofold risk of developing AD compared with controls (HR, 2.06, 95 percent CI, 1.64–2.58). The prevalence of pre-existing AD was also higher in HS patients than in controls (2.5 percent vs 1.8 percent; p<0.001).

Of note, a history of AD contributed to a 40-percent increase in the odds of HS (OR, 1.41, 95 percent CI, 1.19–1.67). Moreover, patients with a dual diagnosis of HS and AD were younger, more likely to be female, had lower prevalence of smoking, and had lower body mass index compared to those with isolated HS.

The study, however, was limited by its retrospective data collection, according to the authors.