Predictive role of loneliness on mortality before the age 85 years among mid- to later-life adults in the United States: a 10-year retrospective cohort study.

AIMS: Loneliness is a common public health concern, particularly among mid- to later-life adults. However, its impact on early mortality (deaths occurring before reaching the oldest old age of 85 years) remains underexplored. This study examined the predictive role of loneliness on early mortality across different age groups using data from the Health and Retirement Study (HRS).

METHODS: A retrospective cohort study was conducted using data from the 2010-2020 waves of the HRS, restricted to participants aged 50-84 years at baseline. Loneliness was measured using the 11-item UCLA Loneliness Scale, categorized into four levels: low/no loneliness (scores 11-13), mild loneliness (14-16), moderate loneliness (17-20) and severe loneliness (21-33). Cox proportional hazards models and time-varying Cox regression models with age as the time scale were created to evaluate the relationship between loneliness and early mortality, adjusting for sociodemographic, lifestyle, and physical and mental health factors.

RESULTS: Among 6,392 participants, the overall mortality rate before the age of 85 years was 19.1 per 1,000 person-years. A dose-response relationship was observed, with moderate and severe loneliness associated with 23% (adjusted hazard ratio [aHR]: 1.23, 95% confidence interval [CI] = 1.02-1.48) and 36% (aHR: 1.36, 95% CI = 1.13-1.65) higher mortality risk, respectively. Significant associations existed for the 65-74-year-old (aHR = 1.37, 95% CI = 1.03-1.83) and 75-84-year-old (aHR = 1.77, 95% CI = 1.23-2.56) age groups in the fully-adjusted models, but not for the 50-64-year-old age group. Time-varying Cox models showed a stronger association for severe loneliness (aHR = 1.65, 95% CI = 1.37-1.99).

CONCLUSIONS: Loneliness is a significant predictor of mortality among older adults. Preventive and interventional programs targeting loneliness may promote healthy ageing.