Effect of happiness and functional disability on older people's survival

The aim was to investigate survival and risk of death within a ten-year period according to physical functioning and frequency of the feeling of happiness in older people, conducting an analysis of the possible mediating effect of happiness on the association between physical functioning and mortality. A retrospective longitudinal study was conducted with 1,519 older people (≥ 60 years) interviewed for the 2008/2009 Health Survey in Campinas. A linkage was made between the databank of the survey and the Campinas Mortality Information System, with active search for confirmation of deaths and non-deaths from 2008 to 2018. Variables of interest were physical functioning (absence/presence of limitations) and frequency of feeling happiness. Kaplan-Meier survival curves were plotted and Cox regression analysis was performed to estimate hazard ratios (HR). A mediation analysis was also conducted using the Karlson-Holm-Breen (KHB) method. In the adjusted analysis, severe functional limitation (HR = 2.8; 95%CI: 2.0-3.8) and low frequency of happiness (HR = 1.6; 95%CI: 1.3-2.0) increased the risk of death in the period. Low frequency of happiness mediated the association between functioning and mortality by 14%. The results underscore the importance of strategies to maintain physical functioning during aging. Moreover, a greater frequency of the feeling of happiness increased the survival of the population. The findings also show that happiness plays an important mediating role in the association between functioning and mortality in older people.