Sociopsychological characteristics of late nonagenarians in Japan: the protocol of the Arakawa 95+ study

Aim: The aim of this study was to examine sociopsychological characteristics of the oldest old in Japan. We conducted a baseline survey of a community-based cohort of persons aged 95 or older. Methods: Participants were aged 95+ years and resided in Arakawa Ward in Tokyo on 1 January 2016. We mailed a questionnaire to these individuals to assess their physical, mental, and social status. Subsequently, if respondents agreed, we conducted in-home interviews and examined their physical and cognitive function. Also, we mailed non-respondents a simplified version of full questionnaire. Additionally, we examined the basic registered data of the study population and the status of their Long-term Care Insurance. Data at baseline and 1-year follow-up were compared. Results: With regard to Long-term Care Insurance, 423 residents aged 95+ years (78.0%) were on long-term care level, 35 (6.5%) were on support level, and 84 (15.5%) did not require support. At the 1-year follow-up, 275 (50.7%) had the same care level, 107 (19.7%) required a greater level of care, and 131 had died (annual death rate: 24.2%). Compared to the simplified questionnaire group (n = 128) and the full questionnaire-only group (n = 14), a higher proportion of respondents who had completed the full questionnaire and had in-home interviews (n = 26) were men, lived only with a spouse, had higher activities of daily living, and reported more positive feelings and well-being. Conclusions: In the late nonagenarian population, the annual death rate was high, and care needs increased rapidly. However, some persons maintained the same care level or even showed improvement and successful ageing.