WEDNESDAY, Jan. 10, 2024 -- The incidence and prevalence of alopecia areata (AA) are increased after COVID-19 infection, according to a research letter published online Jan. 10 in JAMA Dermatology.

Jong-Seung Kim, M.D., Ph.D., from the Jeonbuk National University Medical School in Jeonju, South Korea, and colleagues conducted a propensity score-matched, nationwide, population-based cohort study to examine the association between COVID-19 and AA. The cohort included 259,369 patients with COVID-19 and 259,369 uninfected controls.

The researchers found that the cohort with COVID-19 had an increased risk for telogen effluvium (positive control) compared with the uninfected cohort (adjusted hazard ratio, 6.40); the incidence of negative control outcomes was not different between the groups. Patients with COVID-19 had a significantly higher incidence of AA than controls (43.19 versus 23.61 per 10,000 person-years [PY]), regardless of clinical subtype (adjusted hazard ratio, 1.82). A higher incidence of patchy AA and alopecia totalis and alopecia universalis (AT/AU) was seen for patients with COVID-19 (35.94 and 7.24 per 10,000 PY, respectively) than controls (19.43 and 4.18 per 10,000 PY, respectively). In all groups older than 20 years, the incidence of AA after COVID-19 was significantly increased, with higher risk seen for both male and female patients. The prevalence of AA and AT/AU was significantly higher for patients with COVID-19 (70.53 and 12.39 per 10,000 PY, respectively) than controls (52.37 and 8.97 per 10,000 PY, respectively).

"This study suggested an epidemiologic association between COVID-19 and AA," the authors write. "Further studies are necessary to validate the association between different populations and elucidate the causal relationship between the two conditions."