Alopecia areata and risk of atopic and autoimmune conditions: population-based cohort study

This large UK population-based study shows that people with alopecia areata (AA) have a 40% higher risk of being diagnosed with new-onset atopic and autoimmune conditions compared with a control group. This increased burden of atopic and autoimmune comorbidity supports previous work suggesting that both T helper cell (Th)1 and Th2 immune responses may be implicated in the pathogenesis of AA. Background Alopecia areata (AA) has features of both autoimmune and atopic pathogenesis, but information on the risk of people with AA developing autoimmune and atopic conditions is limited. Objective To assess the prevalence and incidence of atopic and autoimmune conditions in people with AA. Methods This was a population-based cohort study of 8051 adults with newly diagnosed AA (AA group) and 32 204 adults in the matched control group, using the UK Oxford-Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) network primary care database, 2009-2018 (trial registration number: NCT04239521). Baseline prevalence of common atopic and autoimmune conditions, and risk of new-onset atopic and autoimmune disease, were estimated. Results Atopic and autoimmune conditions were more prevalent in the AA group than the control group (atopic 37.2% vs. 26.7%, autoimmune 11.5% vs. 7.9%). The AA group were 43% more likely to develop any new-onset atopic condition [adjusted hazard ratio (aHR) 1.43. 95% confidence interval (CI) 1.28-1.61] and 45% more likely to develop any autoimmune condition (aHR 1.45, 95% CI 1.28-1.66) compared with the control group. When examining individual conditions, the AA group were at increased risk of atopic dermatitis (aHR 1.91, 95% CI 1.67-2.19), allergic rhinitis (aHR 1.32, 95% CI 1.14-1.54), autoimmune hypothyroidism (aHR 1.65, 95% CI 1.35-2.02), systemic lupus erythematosus (aHR 4.51, 95% CI 1.88-10.82) and vitiligo (aHR 2.39, 95% CI 1.49-3.82). There was no evidence for a higher incidence of other conditions examined. Conclusion People with AA have an increased burden of atopic and autoimmune comorbidity. This supports previous work suggesting that both T helper cell (Th)1 and Th2 immune responses may be implicated in the pathogenesis of AA.

Automated summary

This large UK population-based study reveals that individuals with alopecia areata (AA) have a 40% higher risk of developing new-onset atopic and autoimmune conditions compared to a control group, supporting the involvement of both Th1 and Th2 immune responses in the pathogenesis of AA.