[Life prognosis of persons with dementia: Observation of persons registered for long-term care insurance in a community in Japan].

Objectives　This study aimed to observe the life prognosis of persons with dementia during the first five years after registering for long-term care insurance, and to determine the factors affecting their prognosis.Methods　A total of 556 persons, aged 65 years or older newly registered for long-term care insurance in a city in Japan, were observed. The life prognosis of the registered persons was determined using standardized mortality ratio (SMR) with the general population as a standard, and relevant factors were observed in terms of dependence indices of dementia and disability.Results　The mean age of persons newly registered for long-term care insurance was 81.6 years and 63% of them were females. Mortality during the first 4.5 years after registration was 16.7% p.a., with males and those of older age having higher rates. The SMR was 1.80 for all individuals, with males and those of younger age having a higher SMR. The SMR increased with the severity of the disability (higher classes on the disability dependence index) at the time of the registration, while no significant trend was seen in SMR with the dementia dependence index. Multivariate analysis revealed that mortality was dependent on sex (male>female), age (older>younger), disability dependence indices (higher classes>lower classes), and current place of residence (home>facility), while there were no significant trends found in mortality with degree of severity on the dementia dependence indices. The adjusted odds ratios of dying from respective factors were as follow: from sex (male/female, with male as a standard) 0.35 (95% confidence interval 0.24-0.51), from age group (65-74 years/75-84/85+, stepwise with 65-74 years as a standard) 1.84 (1.39-2.47), from disability dependence index (normal/I/Ⅱa/Ⅱb..., stepwise with "normal" as standard) 1.38 (1.21-1.58), and from place of residence (home/facility, with home as a standard) 0.64 (0.42-0.99). When limited to only the elderly with dementia dependence indices of Ⅱa-Ⅳ, the analysis showed similar results.Conclusion　Elderly persons registered for long-term care insurance had higher mortality rates than the general population that was dependent on the disability dependence index, but not on the dementia dependent index. Further studies are therefore necessary to elucidate the factors relevant to the study's finding.