Lifetime incidence and healthcare disparities in alopecia areata: A UK population-based cohort study.

Background: Alopecia areata (AA) is an immune-mediated form of hair loss that can occur at any age, often with a significant mental health burden.

Objectives: We aimed to provide estimates of the lifetime incidence of AA, and the impacts on mental health, healthcare utilisation and work-related outcomes, assessing variation across major sociodemographic subgroups.

Methods: AA cases were identified in primary care from the UK population-based Oxford-Royal College of General Practitioners Research and Surveillance Centre database (2009-2018). Lifetime incidence of AA was estimated at age 80 using modified time-to-event models with age as the timescale, overall and stratified by sex, ethnicity, deprivation, and geography. Mental health, healthcare utilisation and work-related outcomes were assessed in the two years after AA diagnosis compared to matched unaffected controls, and stratified by the same sociodemographic subgroups .

Results: 6,961 people developed AA during the study period. Overall lifetime incidence of AA was 2.11% (95% Confidence Interval [CI] 2.06, 2.16%). Females had a higher lifetime incidence 2.35% (95%CI 2.28, 2.43%) than males 1.88% (95%CI 1.81, 1.94%). Lifetime incidence was higher in those of Asian ethnicity 5.87% (95%CI 5.51, 6.24), other 4.47% (95%CI 3.63, 5.31), mixed 4.44% (95%CI 3.50, 5.37) and black 3.03% (95%CI 2.63, 3.42) ethnicity, compared to white ethnicity 1.74% (95%CI 1.68, 1.80). Lifetime incidence was highest in those with the greatest deprivation; most-deprived quintile 2.92% (95%CI 2.77, 3.07%) compared to least-deprived 1.68% (95%CI 1.59, 1.78%). Across sociodemographic subgroups, people with AA of black ethnicity were most likely to have anxiety (adjusted Odds Ratio versus matched controls 2.92, 95%CI 1.71, 4.91), and had the greatest risk of time off work (adjusted Hazard Ratio versus matched controls 2.54, 95%CI 1.80, 3.56).

Conclusions: AA affects around 1 in 50 people over their lifetime. Incidence and the impact of AA on mental health and work outcomes, is highest in ethnic groups other than white. Clinicians should be aware of the marked heterogeneity in the incidence and impact of AA, and support targeted healthcare to groups at the highest risk of alopecia and its consequences.The study protocol for this retrospective observational study was registered with ClinicalTrials.gov (Identifier: NCT05727306).