Incidence, prevalence and risk of acne in adolescent and adult patients with atopic dermatitis: a matched cohort study

Background: Use of Janus kinase 1 inhibitors in moderate-to-severe atopic dermatitis (AD) is associated with incident acne in adolescent and adults that is mostly mild, transient and treatable. There is a need for more knowledge about the risk and severity of acne in patients with AD. Objectives: To examine the prevalence, incidence and risk of acne in adolescents and adults with AD using nationwide prescription data. Methods: A matched cohort study of 6600 adults with AD and 66 000 controls was conducted using routinely and prospectively collected nationwide administrative data. Adjusted hazard ratios (HR) are reported with 95% confidence intervals (CIs). Results: The 12-month prevalence of acne was 3.7% in the general population and 3.9% among AD patients. The incidence rate of acne was highest among 12- to 18-year-old AD patients, and overall slightly higher in women with AD compared with males. The overall risk in patients with AD was similar with that of the general population (HR 0.96; 95% CI 0.88-1.06), whereas the risk of being treated for severe acne was reduced in AD patients (HR 0.59; 95% CI 0.47-0.73) and mainly among adolescents and young adults. The HR of acne increased with age reaching 1.41 (95% CI 1.07-1.87) for ages 30-39 years, and 2.07 (95% CI 1.42-3.03) for patients ≥40 years compared with controls. Conclusions: The risk and severity of acne in AD patients change with age and sex, which may be used for the risk assessment of acne following treatment with Janus kinase 1 inhibitor