A statistically significant bidirectional association was observed between hidradenitis suppurativa (HS) and atopic dermatitis (AD), according to study findings published in the Journal of the American Academy of Dermatology.

Researchers conducted a population-based, retrospective cohort study to compare the incidence rate of AD among patients with HS (n=6779) with those in an age-, gender-, and ethnicity-matched control group (n=33,260). The mean (SD) age at diagnosis was 33.1 (15.1) years; 2708 (39.9%) patients were men or boys, and 5607 (82.7%) patients were of Jewish ancestry. The prevalence of smoking, mean body mass index (BMI), and the mean Charlson Comorbidity Index score were significantly greater in affected patients than in individuals in the control group.

The study authors found that the incidence of AD was 2.51 (95% CI, 2.07-3.02) and 1.24 (95% CI, 1.10-1.40) per 1000 person-years among patients with HS and individuals in the control group, respectively. Patients with HS were twice as likely to develop AD compared with those in the control group (hazard ratio [HR], 2.06; 95% CI, 1.64-2.58). The prevalence of pre-existing AD was higher among patients with HS than for those in the control group (2.5% vs 1.8%, respectively; P <.001). A history of AD was associated with a 40% increase in the odds of HS (OR, 1.41; 95% CI, 1.19-1.67).


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“Patients with HS experience a 2-fold elevated risk of developing subsequent AD, whereas a history of AD was associated with a 40% increase in the odds of having subsequent HS,” the investigators commented. “HS patients with comorbid AD were more likely to be younger, female, nonsmokers, with lower BMI than patients with HS without AD.”

Among several study limitations, the registry data do not include clinical information about severity and clinical features of both HS and AD, and therefore phenotypes of the subset of AD/HS patients cannot be determined. The researchers also lacked data about familial history of atopic diathesis or HS, which could help validate both diagnoses and indicate the presence of a genetic pathway between the 2 diseases.

“The current large-scale population-based study indicates that patients with HS have an increased risk of AD, and that a history of AD predisposes individuals to have subsequent [HS],” the study authors concluded. “This knowledge may be of great interest for dermatologists managing patients with these conditions and may increase the awareness for this comorbidity.”

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

Reference

Sherman S, Kridin K, Bitan DT, Leshem YA, Hodak E, Cohen AD. Hidradenitis suppurativa and atopic dermatitis: a two-way association. Published online December 27, 2020. J Am Acad Dermatol. doi:10.1016/j.jaad.2020.12.051