OBJECTIVES : The Diabetes Prevention Program (DPP), one of the landmark clinical trials in endocrinology, demonstrated that lifestyle interventions could reduce type 2 diabetes incidence and treatment costs as compared to placebo. Thus, this study aimed to investigate whether lifestyle interventions were cost-effective in the Japanese context.

METHODS : We analyzed the cost-effectiveness of preventive interventions for prediabetic patients from the perspective of a Japanese public health care payer using a mathematical model. The preventive intervention program used in this study included nutritional and exercise guidelines based on Japan's Specific Health Guidance by the Ministry of Health, Labor, and Welfare in Japan, and the DPP, which was eligible for those at age 50 years. Lifetime costs and quality-adjusted life years (QALYs) were estimated in lifestyle interventions and in no-interventions, and the incremental cost-effectiveness ratio (ICER) of the lifestyle interventions was estimated. A Markov model was then developed, consisting of three health states: prediabetes, T2D, and death. Time horizon and cycle length were set to lifetime and 1 year, respectively, and an annual discount rate of 2% for both costs and QALYs was applied.

RESULTS : Base case analysis showed that incremental cost and incremental QALYs of lifestyle intervention was -$1,610 and 0.20, respectively, resulting in dominant compared to no-interventions. The parameter with the greatest impact on base case outcome was T2D mortality rate in no-interventions. If this parameter was varied by ±10%, ICER would have exceeded a societal willingness to pay threshold of $50,000 per QALY. Lifestyle interventions would also bewere dominant, if the subject was aged 40 or age 60 years, or if the effect was assumed to be 20% lower.

CONCLUSIONS : This study revealed that lifestyle interventions for prediabetic patients in Japan were cost-effective as compared to no-interventions. These findings would be attributable to health policy decision making in Japan.