Risk factors for frontal fibrosing alopecia: A case-control study in a multiracial population.

Background: Frontal fibrosing alopecia (FFA) is a chronic cicatricial alopecia with unknown etiology and a worldwide rising incidence.
Objective: The objective of this study was to evaluate the association of FFA with demographic and exposure factors in a Brazilian multiracial population.
Methods: A multicenter case-control study was conducted in 11 referral centers throughout Brazil. The study was a case-control study that prospectively recruited 902 participants (451 patients with FFA and 451 sex-matched control individuals). Study participants completed a thorough questionnaire comprising variables grouped as baseline demographics, environmental exposure, diet, hormonal factors, allergies, and hair and skin care.
Results: When adjusted by sex, age, menopause, and skin color, FFA was associated with hair straightening with formalin (odds ratio [OR], 3.18), use of ordinary (nondermatologic) facial soap (OR, 2.09) and facial moisturizer (OR, 1.99), thyroid disorders (OR, 1.69), and rosacea (OR, 2.08). Smokers (OR, 0.33) and users of antiresidue/clarifying shampoo (OR, 0.35) presented a negative association with FFA. There was no association with the use of sunscreen.
Limitations: Recall bias.
Conclusions: The association with moisturizers, ordinary facial soap, and hair straightening with formalin and the negative association with antiresidue/clarifying shampoo reinforce the possibility of an exogenous particle triggering FFA.
(Copyright © 2020 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)