Living alone, socioeconomic status, and mortality among older adults: a population-based cohort study

This study examined the association between living alone, socioeconomic status, and mortality among community-dwelling older adults. We analyzed mortality outcomes among 3,771 participants aged ≥ 60 years enrolled in the Korean Longitudinal Study of Aging (KLoSA) beginning in 2006. Participants were followed until the date of death or December 31, 2020, whichever occurred first. All-cause, cancer, and cardio-cerebrovascular (CCV) mortality were compared between individuals living alone and those living with others using Cox proportional hazards models and inverse probability of treatment weighting (IPTW). Subgroup analyses were conducted to assess cause-specific mortality according to various social and functional factors. In the weighted model, the mean age was 70.0 ± 7.5 years for those living with others and 70.2 ± 6.7 years for those living alone. Living alone was associated with higher all-cause, cancer, and CCV mortality after adjustment for demographic and behavioral factors (adjusted hazard ratio [aHR], 95% confidence interval [CI]: 1.49 [1.30–1.70], 1.81 [1.32–2.47], and 1.92 [1.46–2.53], respectively). However, after IPTW adjustment for socioeconomic factors, these associations were no longer statistically significant, suggesting that living alone may not be an independent causal factor but rather a proxy for underlying socioeconomic vulnerability. Among older adults living alone, those in the low-income subgroup had significantly higher all-cause and CCV mortality (aHR 1.33, 95% CI 1.04–1.68; and aHR 1.68, 95% CI 1.06–2.66, respectively). Living alone with close contact at least once per week was not associated with increased mortality, whereas those meeting close contacts between once per year and once per week showed a borderline increase in CCV mortality (aHR 2.72, 95% CI 0.95–7.77). Notably, individuals with no close social relationships over the past year exhibited a significantly increased risk of CCV mortality (aHR 3.41, 95% CI 1.20–9.69). We found that although living alone is associated with mortality, adjustment for social and functional factors may attenuate this association. However, specific subgroups with low income, and scarce social relation lead to increased CCV mortality. Further study with a larger sample size is necessary to confirm this finding.