Time-Dependent Risk of Acute Myocardial Infarction in Patients With Alopecia Areata in Korea

Importance Alopecia areata (AA) is a common autoimmune disease presenting as nonscarring hair loss. Although AA can be associated with other autoimmune comorbidities or atopic diseases, little is known about the risk of cardiovascular diseases in patients with AA. Objective To investigate the risk of acute myocardial infarction (AMI) and cardiovascular risk profiles (CVRPs) in patients with AA via a large-scale epidemiologic study. Design, Setting, and Participants This was a retrospective cohort study using data from the Korean National Health Insurance claims database, including data from the National Health Screening Program. Patients aged 30 to 89 years who were newly diagnosed with AA between January 1, 2006, and December 31, 2017, and controls without AA matched by age and sex were enrolled. Data were analyzed between July 2018 and August 2019. Exposures Presence of AA. Main Outcomes and Measures The CVRPs and incidence rates of AMI were assessed in participants with and without AA. The stratified Cox regression hazard model was used to estimate the relative hazards over time. Results A total of 228 886 patients with AA, ranging in age from 30 to 89 years (mean [SE] age, 44.37 [0.005] years; 127 564 [55.7%] men) and 4 577 720 matched controls without AA were identified. Patients with AA tended to have slightly better CVRPs than controls in all items except smoking status before and after the diagnosis (participants with normal systolic blood pressure who were nonsmokers: 44.6% vs 42.7% and 57.8% vs 61.6% in patients with AA vs controls before and after the diagnosis, respectively). In the early phase of observation, the cumulative incidence of AMI in patients with AA was lower than that in controls (incidence rate ratio of AMI in patients with AA compared with that in controls, 0.52 [95% CI, 0.42-0.65] between 2-4 years); however, during the later phase of the 12-year follow-up period, it increased exponentially and was greater than in the control group (incidence rate ratio, 2.06 [95% CI, 1.71-2.45] between 8-10 years). Similarly, after adjusting for CVRPs, the risk of developing AMI was lower in patients with AA than in controls at the beginning of the observation period (adjusted hazard ratio (HR), 0.17 [95% CI, 0.12-0.25] between 0-2 years); however, by 8 years postdiagnosis, the risk was higher in those with AA (adjusted HR, 1.37 [95% CI, 1.11-1.70] between 8-10 years), and it increased thereafter (adjusted HR, 4.51 [95% CI, 3.65-5.58] between 10-12 years). Conclusions and Relevance In patients with AA, there was a significantly increased risk of AMI over time during the 12-year follow-up period independent of CVRPs. Close long-term monitoring of cardiovascular health in patients with AA might be appropriate.