BackgroundPremature death in individuals with severe mental illness (SMI) in countries without nationally collected data, including Japan, is structurally underreported.AimsTo elucidate excess mortality among individuals with SMI in Japan.MethodWe retrospectively investigated all deaths among users of a non-clinical community-based mental health service provider in suburban Tokyo from 1992 to 2015.ResultsDuring the study period, 45 individuals died among 254 qualified registrants. Deaths were by natural causes in 33 cases (73.3%). The mean years of life lost was 22.2 years and the overall standard mortality ratio (SMR) was 3.28 (95% CI 2.40–4.39). The cause-specific SMR was 5.09 (95% CI 2.33–9.66) for cardiovascular disease and 7.38 (95% CI 2.40–17.22) for suicide.ConclusionsAlthough Japan leads the world in longevity, individuals with SMI suffer premature death and excess mortality due to physical conditions as well as suicide. Revealing this underreported disparity of life is the first step to improving physical care for individuals with SMI.Declaration of interestS.K. received personal fees from Pfizer and Dainippon-Sumitomo, outside the submitted work, and was a medical adviser to Sudachi-kai. Y.K. received grants from Japan Foundation for Neuroscience and Mental Health (JFNMH), during the conduct of the study, and personal fees from Dainippon-Sumitomo, outside the submitted work. K.K. received grants from Japan Society for the Promotion of Science (JSPS) and Japan Agency for Medical Research and Development (AMED), during the conduct of the study; personal fees from Daiichi-Sankyo, Otsuka, Meiji-Seika Pharma, Yoshitomi, Mochida and Fuji-Film RI Pharma; grants and personal fees from MSD, Astellas, Dainippon-Sumitomo and Eisai; and grants from Lily, Takeda and Tanabe-Mitsubishi, outside the submitted work.Copyright and usage© The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.

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