Living alone and risk of mortality from all-cause and 15 specific causes-a nationally representative cohort study of US adults.

Background

Living alone has been associated with higher mortality, but evidence for specific causes of death and potential drivers of these associations is limited. We examined associations between living alone and cause-specific mortality, and the extent to which sociodemographic and health-related characteristics explained these associations.

Methods

This study included 598 023 US adults aged ≥18 years from the 1998-2018 National Health Interview Survey-National Death Index (follow-up through 2019). Cox proportional hazards models estimated hazard ratios (HRs) and Blinder-Oaxaca decomposition quantified contributions of measured characteristics.

Results

Adults living alone aged 18-64 and ≥65 years were at higher risk of mortality from all causes combined [HR18-64 = 1.22 (95% CI: 1.18-1.26); HR≥65 = 1.06 (1.03-1.08)], heart disease [HR18-64 = 1.41 (1.32-1.50); HR≥65 = 1.11 (1.06-1.15)], suicide [HR18-64 = 1.58 (1.30-1.92); HR≥65 = 2.03 (1.47-2.81)], and all injuries [HR18-64 = 1.27 (1.16-1.40); HR≥65 = 1.16 (1.02-1.32)], respectively, compared to adults living with others. Adults living alone were also at higher risk of mortality from cerebrovascular disease [HR18-64 = 1.23 (1.04-1.46)], colorectal cancer [HR18-64 = 1.27 (1.06-1.53)], diabetes [HR18-64 = 1.34 (1.15-1.57)], and accidents [HR18-64 = 1.17 (1.04-1.31)] in ages 18-64 and from hypertension [HR≥65 = 1.28 (1.07-1.53)] in ages ≥65 years. Sociodemographic and health-related characteristics explained 57.1% and 85.4% of the all-cause mortality difference by living arrangement in ages 18-64 and ≥65 years, respectively, with some variations in contributing characteristics across causes of death.

Conclusions

Individuals living alone had an increased risk of death from multiple causes, particularly in ages 18-64 years, with the highest risk for suicide in all ages. Mortality differences were largely explained by sociodemographic and health-related characteristics, highlighting targeted interventions to reduce mortality risks among those living alone.