Alopecia areata and risk of common infections: a population-based cohort study

This is a population-based study exploring associations between alopecia areata (AA) and common infections and although we found that the incidence of common infections was slightly higher in people with AA we found no association between AA and infection. Our findings suggest that the slightly higher incidence of common infections may represent a higher propensity of people with AA to engage with healthcare services (and thereby to have infections recorded), rather than a true association. Background It is not known whether alopecia areata (AA) is associated with a greater or reduced risk for infection. Aim We undertook a population-based study exploring associations between AA and common infections. Methods We extracted primary care records from the UK Oxford-Royal College of General Practitioners Research and Surveillance Centre database (trial registration: NCT04239521). The incidence of common and viral infection composite outcomes, and individual respiratory, gastrointestinal (GI), skin, urinary tract, genital and herpes infections, were compared in people with AA (AA group, n = 10 391) and a propensity-matched control group (n = 41 564). Adjusted hazard ratios (aHRs), controlling for sociodemographic and clinical covariates, and comorbidities were used to estimate the association between AA and each infection over 5 years. Results The incidence (per 100 person-years) of common infections was slightly higher in the AA group [14.2, 95% confidence interval (CI) 13.8-14.6] than the control group (11.7, 95% CI 11.5-11.9). In adjusted analysis, positive associations were observed for composite outcomes (common infections aHR 1.13, 95% CI 1.09-1.17; viral infections aHR 1.11, 95% CI 1.07-1.16) and with respiratory tract, GI, skin and herpes simplex infections (aHR range 1.09-1.32). Excluding people in the control group without a recent consultation with their general practitioner showed no association between AA and infection (common infections aHR 1.01, 95% CI 0.98-1.05, viral infections aHR 0.99, 95% CI 0.95-1.03). Conclusions The association between AA and common infection may represent a higher propensity of people with AA to engage with healthcare services (and thereby to have infections recorded), rather than a true association between AA and infection. Overall our findings suggest that AA is not associated with a clinically significantly increased or decreased incidence of common infections.

Automated summary

This population-based study explored the association between alopecia areata (AA) and common infections. Although a slightly higher incidence of common infections was found in people with AA, no association between AA and infection was observed. The findings suggest that the higher incidence of common infections in people with AA may be due to their higher healthcare utilization, rather than a true association.