A study on the mortality patterns of missing and deceased persons with dementia who died due to wandering

To clarify the mortality patterns derived from differences in the causes of death and to subsequently promote search activity and prevent the death of missing persons.

The Ministry of Health, Labour and Welfare (MHLW) performed a mail survey using a self-administered questionnaire. The families of all 388 deceased dementia patients from among all of the missing persons reports involving dementia patients that were submitted to the police in 2013, and the 10,322 missing persons with dementia (or suspected cases) were the subjects of this survey. The survey was conducted from January 5 to February 2 in 2015. We analyzed the data provided by the MHLW on 61 cases in which the cause of death was recorded; the factors that were related to the differences in the causes of death were examined using a chi-squared test (Fisher's direct method) and a residual analysis. Based on previous studies, we classified the causes of death into three categories: "drowning," "hypothermia," and "others (e.g., traumatic injury, disease progression)."

When the cause of death was hypothermia, death often occurred between three to four days from the time that the deceased individual went missing. A significantly higher number of patients who died of other causes were found to have died on the day that they went missing. More than 40% of the drowning cases occurred on the day that the deceased individual went missing.

We identified 3 patterns of mortality: (1) death on the day that the deceased individual went missing due to traumatic injury, disease progression, drowning, and other causes; (2) death due to hypothermia within a few days after the deceased individual went missing; and (3) patterns other than (1) and (2).