Systemic Autoimmune Comorbidity in Alopecia Totalis and Universalis Compared with Patchy Alopecia Areata: A Retrospective Cohort Study

This retrospective cohort study compared systemic autoimmune comorbidities in patients with alopecia totalis/universalis (AT/AU) and patchy alopecia areata (AA) using data from the TriNetX Global Collaborative Network. The study included 9,805 patients in each group, matched for age, sex, race, and prior inpatient encounters. Results showed that systemic autoimmune diseases were more prevalent in the AT/AU group (14.9%) compared to the patchy AA group (11.0%), with a relative risk (RR) of 1.35. Endocrine autoimmunity and inflammatory bowel disease were notably higher in the AT/AU group, with RRs of 1.64 and 1.44, respectively. The findings suggest that AT/AU is associated with a higher burden of systemic autoimmunity, particularly driven by endocrine and inflammatory bowel diseases, indicating a broader autoimmune phenotype in these patients.