Incident Asthma, Asthma Exacerbations, and Asthma-Related Hospitalizations in Patients With Atopic Dermatitis.

ABSTRACT

BACKGROUND: Atopic dermatitis (AD) is thought to induce asthma via the "atopic march," but the effects of AD on incident asthma and asthma severity have not been fully characterized. OBJECTIVE: To determine risk of asthma, asthma exacerbations, and asthma-related hospitalizations among patients fwith AD. METHODS: A cohort study was conducted using electronic health records data from UK general practices from 1994 to 2015. Children (<18 years old) and adults (≥18 years) with AD were matched on age, practice, and index date to patients without AD. AD severity was categorized using treatments and dermatologist referrals. Outcomes were incident asthma among all patients and asthma exacerbation or hospitalization among patients with asthma. RESULTS: On comparing 409,341 children with AD (93.2% mild, 5.5% moderate, 1.3% severe) with 1,809,029 unaffected children, those with AD were found to be associated with a 2-fold greater risk of asthma compared with those without AD (hazard ratio, 1.96; 95% CI, 1.93-1.98). On comparing 625,083 adults with AD (65.7% mild, 31.4% moderate, and 2.9% severe) with 2,678,888 unaffected adults, AD was found to be associated with a 38% higher risk of asthma (hazard ratio, 1.38; 95% CI, 1.36-1.40). Asthmatic patients with AD also had a 21% to 63% greater risk of asthma exacerbations and a 20% to 64% greater risk of asthma-related hospitalizations compared with asthmatic patients without AD. Risk of asthma, asthma exacerbation, or asthma-related hospitalization increased with AD severity in a dose-dependent manner in both the pediatric and adult cohorts. CONCLUSIONS: AD, especially in children and when more severe, is associated with greater risk of asthma as well as greater risk of asthma exacerbations and hospitalizations among asthmatic patients.