Factors linked to subjective life expectancy in a national longitudinal research conducted in Thailand between 2015 and 2022 among community-dwelling people 80 years of age and older

The factors influencing subjective life expectancy (SLE) in people 80 years of age and older have not received enough attention in numerous research. This study used Thailand’s four-wave national longitudinal data to examines whether within-person changes in biomedical, socioeconomic, health-behavioural, and psychosocial factors are associated with changes in SLE across waves among people aged 80 and over. The Health, Aging, and Retirement in Thailand (HART) research, which was carried out in 2015, 2017, 2020, and 2022, provided the data we used. Only people 80 years of age and older who lived in the community were included in the sample (analytic sample: n = 3113 observations). The pooled sample’s age ranged from 80 to 107 years, with an average of 85.4 years. SLE was defined as each age group’s estimated probability of living a further 10 to 15 years, ranging from 0% to 100%. Numerous metrics, such as the state of one’s physical and mental health, were evaluated using established measurements. Linear fixed effects regression was used to assess the time-varying independent covariates (biomedical, socioeconomic, health behavioural, and psychological) and outcome (SLE). Regressions revealed that increases in age, transitioning to widowed, transitioning to not working, engaging in annual health check-up, purchase of a health insurance, higher quality of life, higher self-rated mental and physical health increased SLE and increases in functional disability, transitioning to living alone, and higher meal skipping decreased SLE. We discovered that SLE was linked to biological, socioeconomic, health-related behavioural, and psychosocial factors. Improving psychosocial and health behaviour in the oldest-old may help in increasing SLE.