Diphenylcyclopropenone in patients with alopecia areata. A critically appraised topic

To assess the efficacy and safety of topical diphenylcyclopropenone (DPCP) in patients with alopecia areata.

Study selection, data extraction, risk of bias assessment and analyses were carried out independently by two authors. The quality of evidence was rated with Grading of Recommendations Assessment, Development and Evaluation (GRADE). No randomised trials were identified, but 11 case series, conducted in dermatology departments in the Netherlands, UK, Iran, Italy, Egypt and Greece were included.

Patients with mainly extensive and long-lasting alopecia totalis and universalis were treated. Most often one side of the scalp was treated with DPCP whilst the other side received no treatment. Treatment duration varied from 4 to 48 months with a follow up of 6 to 36 months.

Outcomes included quality of life, patient satisfaction, adverse events, treatment effect and duration of remission.

Eleven studies, with sample sizes of 18-139 comprising 500 patients, were retrieved. Our critical outcomes quality of life and patient satisfaction, were not or hardly addressed. In about half of the patients DPCP appeared to be effective, with transient side effects such as contact eczema, blistering, oedema of eyelids, headache and flu-like symptoms. If treatment was satisfactory the effect was maintained for more than a year. The overall quality of the evidence was rated very low.

There is very low quality evidence for the effectiveness and safety in extensive resistant alopecia areata. Well-designed and well-conducted randomised controlled trials, with subsequent adequate reporting, including high-quality descriptions of all aspects of methodology are required.