Prevalence of kodokushi (solitary deaths) in the Tokyo metropolitan area

Kodokushi or solitary deaths is one of the most important socio-medico problems in Japan that has emerged because of a super-aging society. In this paper, we provide the long-term trends and associated social risk factors of kodokushi in Tokyo, the only city that publishes detailed records of kodokushi in Japan. Overall, our results show that the age-adjusted mortality rate of kodokushi in the Tokyo Metropolitan area has consistently increased from 2003 to 2010, but since then has remained mostly unchanged in both genders. By age group, the age-adjusted mortality rate of kodokushi has increased throughout the study period of 2003–2016 in those aged ≥ 60. Males and those aged 60–69 and 70–79 years have notably higher odds of kodokushi. Since a quarter of all kodokushi cases in Tokyo were under the age of 60 in 2016, the issue may gain population-wide relevance in the future. More studies in this line are required for targeted public health policy to prevent kodokushi.