Evaluation of the efficacy of maintenance therapy for acne vulgaris using adapalene 0.1%/benzoyl peroxide 2.5% gel and benzoyl peroxide 2.5% gel for 24 weeks and assessment of atrophic acne scars using three‐dimensional image analysis

Maintenance therapy after remission of inflammation is strongly recommended in the guideline for the treatment of acne vulgaris published by the Japanese Dermatological Association. One advantage of continuing maintenance therapy is the alleviation of atrophic scarring. This study investigated the efficacy of maintenance therapy using adapalene 0.1%/benzoyl peroxide 2.5% gel and benzoyl peroxide 2.5% gel, and its effects on atrophic scarring. Overall, 126 patients were randomized to the adapalene/benzoyl peroxide group (n = 40), benzoyl peroxide group (n = 44), and control group (without maintenance treatment drugs; n = 42), and 111 of these completed a trial lasting 24 weeks. As the primary endpoint, the treatment success rate (the percentage of patients in whom the number of inflammatory lesions was maintained at ≤10) was 89.2% in the adapalene/benzoyl peroxide group, 87.5% in the benzoyl peroxide group, and 47.4% in the control group. Compared with the control group, the success rates were significantly higher in the adapalene/benzoyl peroxide and benzoyl peroxide groups (P = 0.0006 for both). As one of the secondary endpoints, the rate of change in the number of atrophic scars showed significant improvement from the baseline in the adapalene/benzoyl peroxide and benzoyl peroxide groups at week 24 (P = 0.0004 and P < 0.0001, respectively). Although the three-dimensional image analysis parameters did not change significantly from the baseline in the adapalene/benzoyl peroxide and benzoyl peroxide groups at week 24, significant worsening was noted in the control group (P = 0.0276 for affected area, P = 0.0445 for volume, and P = 0.0182 for maximum depth). Adverse drug reactions were noted in three patients in the adapalene/benzoyl peroxide group (7.5%) but not in the benzoyl peroxide group. These findings suggest that maintenance therapy using adapalene 0.1%/benzoyl peroxide 2.5% gel and benzoyl peroxide 2.5% gel is effective in preventing the worsening of scars in Japanese patients with acne vulgaris.