Cost-Effectiveness Study of Difamilast 1% for the Treatment of Atopic Dermatitis in Adult Japanese Patients.

INTRODUCTION

Difamilast has proven to be an effective treatment for the treatment of atopic dermatitis (AD) in Japan, but its cost-effectiveness remains unknown. Therefore, the objective of the current study was to determine the cost-effectiveness of difamilast 1% compared with delgocitinib 0.5% in Japanese adult patients with moderate-to-severe AD and compared with placebo in Japanese adult patients with all-severity AD from a Japanese public health-care perspective.

METHODS

The analysis was conducted using a cost-effectiveness model from the Japanese public health-care perspective. This model had four health states ("clear," "mild," "moderate," and "severe") defined according to the Eczema Area and Severity Index score. The time horizon of the analysis was 1 year. Because the analysis period was short, no discount rate was applied. The proportions of patients previously estimated by the anchored matching-adjusted indirect comparison were implemented in the model. The model was further populated with data from the literature. The main model outcomes were quality-adjusted life-years (QALY), costs, and outcomes, including the incremental cost-effectiveness ratio. All prices were stated in JPY at the price level from 2018 April to 2019 March. One-way sensitivity analysis and probabilistic sensitivity analysis (PSA) were performed to assess the robustness of the results.

RESULTS

In the base case, the cost-effectiveness of difamilast 1% compared with delgocitinib 0.5% and placebo was JPY 827,054/QALY and JPY 1,518,657/QALY, respectively. The PSA showed that the cost-effectiveness of difamilast 1% compared with delgocitinib 0.5% and placebo had a 66.6% and 99.6% probability of being below the JPY 5 million/QALY threshold, respectively.

CONCLUSION

The results suggest that difamilast 1% is a more cost-effective treatment option compared with delgocitinib 0.5% in Japanese adult patients with moderate-to-severe AD and compared with placebo in adult patients with all-severity AD from a Japanese public health-care perspective.