Incidence and Mortality of Dementia-Related Missing and Their Associated Factors: An Ecological Study in Japan

Background: Dementia-related missing and subsequent deaths are becoming serious problems with increases in people with dementia. However, there are no sufficient studies investigating the incidence rate, the mortality rate, and their risk factors. Methods: An ecological study aggregated at the Japanese prefectural level was conducted. Dementia-related missing persons cases and deaths in 2018 were extracted from the statistics of the National Police Agency in Japan. We extracted variables about older adults’ characteristics, care, and safety as candidate variables considered to be relevant to dementia-related missing persons cases and deaths. Associations of the candidate variables with the incidence and mortality rates were analyzed using the generalized linear model (family: quasi-poisson, link: log) adjusted for confounding factors (proportion of older adults and gross prefectural product). Results: The incidence rate and mortality rate per 100,000 person-year was 21.72 and 0.652 in Japan, respectively. One facility increase in the number of nursing care facilities for older adults per 100,000 persons aged 65-years-old or more was associated with a 7.9% (95% confidence interval [CI], 3.3–12.4%) decrease in the incidence rate. One increase in the number of public health nurses per 100,000 persons was associated with a 3.2% (95% CI, 1.6–4.9%) decrease in the incidence rate. A ten percent increase in the proportion of people who live in an urban area was associated with a 20.3% (95% CI, 8.7–33.2%) increase in the incidence rate and a 12.9% (95% CI, 5.6–19.8%) decrease in the mortality rate. Conclusions: Identified associated factors may be useful for managing or predicting dementia-related missing persons cases and associated deaths.