The objective of our study is to evaluate the prevalence and health care cost of malnutrition in Japan. Using the health insurance data, we defined 2 types of malnutrition, strictly diagnosed malnutrition (SDM) and disease-associated malnutrition (DAM) by International Classification of Diseases 10th Revision. We also analyzed the health care costs by body mass index (BMI) data from medical checkups. The nationwide prevalence of SDM was estimated 0.8%, and that of SDM plus DAM was 2.9%. The total annual health care cost for SDM patients in Japan was $14.5 billion, representing 4.3% of the national health expenditures in 2014; the excess cost for patients with SDM was estimated to be $9.7 billion. The health care costs became high among the patients with either low BMI or high BMI. Because of the rapidly aging population, actions are urgently needed to avoid increasing the current high health care costs of malnutrition.
Keywords: Japan; body mass index; health care cost; health insurance data; malnutrition.