The Efficacy, Safety, and Recurrence Rate of Diphenylcyclopropenone Topical Immunotherapy for Alopecia Areata: A Systemic Review and Meta-Analysis

Background and Objective. Diphenylcyclopropenone topical immunotherapy is widely used in the treatment of alopecia areata. However, previous studies have shown significant differences in its efficacy. We conducted this systemic review and meta-analysis to investigate the efficacy, safety, and recurrence rate of diphenylcyclopropenone topical immunotherapy for alopecia areata. Methods. Literatures related to diphenylcyclopropenone topical immunotherapy for alopecia areata between January 1st, 2002, and July 2nd, 2022, were searched in the following databases: PubMed, Embase, Cochrane Library, Sinomed, WanFang Data, and Chinese Medical Journal Network. Results. This meta-analysis included a total of 40 moderate to high quality studies involving 3,002 patients. The overall rate of any hair regrowth was 69%, and the overall rate of complete hair regrowth was 23%. The rate of any hair regrowth in patients with alopecia totalis or alopecia universalis was 42%, and the rate of any hair regrowth in patients with other types of alopecia areata was 75%. Common side effects were mild contact dermatitis (36%), severe contact dermatitis (31%), regional lymphadenopathy (22%), hyperpigmentation (22%), and hypopigmentation (7%). The recurrence rate was 37%. Conclusion. Diphenylcyclopropenone topical immunotherapy is an effective treatment for various types of alopecia areata, and most of its common side effects are acceptable.