We assessed the factors affecting PMI-f using Cox regression models on forensic medical data. These results showed that living alone was the single most influential factor contributing to delays in finding elderly dead body. Other factors included death attributable to external causes, and younger age. We also considered interactions between household situation and other the independent variables, and found additional effects on delays in finding the dead body. These interactions may be interpreted in a multicausal model and our model referred to more empirical conclusion. To our knowledge, this is the first published study to conduct statistical analyses with estimated models to reveal factors related to PMI ‘until finding.’
The analyses demonstrated that living alone was the strongest predictor of delays in finding elderly dead bodies; the risk was about four times higher in this group than in those living with family. This finding suggests that elderly subjects living alone were isolated and contactless. One study surveyed survival after falling among people living alone in San Francisco.13
Of 387 people, 90 were left un-rescued for an average of 18 h after becoming helpless in their own homes and died. Citizens living alone were difficult to find if they fell down. In Japan, the proportion of community-dwelling elderly individuals living alone is increasing with ageing. The proportion of elderly individuals living alone among whole elderly people was 13.8% in 2000 and 16.4% in 2010.14
This high risk to left the dead body for long time in living alone became an urgent public health issue.
We found the contrary results regarding sex between household situations (living alone or with family). ‘Male subjects living alone’ and ‘female subjects living with family’ tended to prolong their PMI-f. Male elderly people, in general, are said to have poor social relation. Thus, their dead bodies should be difficult to be found by their neighbourhoods or friends. However, among the subjects living with family, male subjects tend to be found their dead bodies than female subjects. In cases of male people, their family member will make more effort to seek. This might be due to the presence of souse. In Japan, the life expectancy is longer in female people than in male15
and the age of a husband used to be older than his wife.15
It is suggested that the number of female widows were greater than male.
Interaction between living alone and dying at one's own home showed effect on PMI-f. This interaction showed the situation that elderly individual's home could be a risk factor to make them more isolated. This risk indicates the need for automatic alarm-and-notification systems. Some municipalities provide such systems connected to local rescue services.17
If accidents occur, the systems can notify to rescue services. In addition to these systems, an important first step in preventing solitary death is to raise public awareness of the likelihood that elderly people living alone may become helpless and isolated in their homes within a community.
Regarding the causes of death included in our model, unnatural causes (eg, drowning, suffocation and falling) were associated with the fact that they are found later. It is natural that the people who were under medical care with some internal diseases can be found earlier. In contrast, external accidents happen suddenly, and therefore it is difficult for relatives to find the dead bodies. In really, the biggest single cause of incapacitation that was left alone was reported to be a fall.13
In our adjusted model, younger individuals’ deaths were found later. This suggests that accidents may have had a bigger impact on younger elderly than older individuals because the former may have been less concerned about death. The situation in which an individual dies and her/his dead body is found can be affected by her/his life and relationships while alive, especially in cases of unfortunate accidents. With a little of individual's concern and correspondence about her/his possibility of death, the people around her/him also can less take care of her/him death and find the dead body later.
We found differences between the crude and adjusted models with regard to significant variables. The identity of the person who found the dead body did not affect the PMI-f in the adjusted model. This indicates that who found the dead body depended on other factors and so that there was no directive this variable's association to PMI-f.
Our present study had several limitations. Variable settings were based on the official record written about the living and dying among the subjects by police officers. Variables including basic characteristics and other components were confirmed to be recorded. Those records were based on the inquires by the police office; however, the accuracy of the information was not secured and it is difficult to assess the validation retrospectively. All of our study subjects were the cases that were reported as unexpected deaths and that were examined by police officers. This reporting system abides by law with compulsion for medical doctors. However, there should be unexpected deaths that are not reported and not performed autopsies. For example, if the doctors have known the family and attended the elderly before, they may not report the unexpected death. If such underreported cases were present, our PMI-f should be longer than actual one because PMI-f in such cases may not be so long. Other situations also may present. Our results should be captured under this limitation.
The PMI-f was analysed as an outcome in our multivariate model for the first time. Our results showed who, how, and how long a time elderly individuals’ bodies tend not to be found. These findings can provide the basis for more effective measures to prevent the phenomena of solitary death among elderly individuals; the delays in finding the bodies of elderly individuals that lead to regrettable postmortem changes. This study should help policy makers to identify and counsel of citizens at risk and to assess priorities for their services given limited budgets. Future studies should evaluate interventions designed to prevent solitary death among elderly individuals and this PMI-f could be a useful quantitative indicator.