Incremental Information from Repeated Loneliness Assessments in Middle-Aged and Older Adults

Background/Objectives: Loneliness can persist, resolve or develop over time. We examined whether repeated assessments add information about health beyond an initial assessment and which health domains account for that information. Methods: The primary analysis included 4904 women aged ≥45 years in the China Health and Retirement Longitudinal Study (CHARLS). Loneliness was assessed in 2011, 2013 and 2015. The outcome combined worsening depressive symptoms, physical function and cognition over 2011–2018, although some physical measurements ended in 2015. Thus, exposure and outcome periods overlapped. We compared models using baseline information alone with models adding the later assessments, testing both in held-out participants. Post hoc analyses included 4287 men. The Health and Retirement Study (HRS) provided a longitudinal comparison in women and additional analyses in men; UK Biobank provided a baseline comparison in women only. Results: Repeated assessments modestly increased explained variation in CHARLS (averaged difference in R-squared [ΔR2] = 0.0178, 95% confidence interval [CI] 0.0103–0.0254 in women; 0.0148, 95% CI 0.0067–0.0228 in men). Associations were strongest for depressive symptoms and everyday function, smaller for cognition, and near null for metabolic and inflammatory markers. There was no clear evidence of sex or age differences in the tested associations. HRS gains were modest in women and imprecise in men. UK Biobank used a different joint loneliness and low-confiding measure. Conclusions: Repeated loneliness assessments added modest information, chiefly about psychological and functional burden. Overlapping measurement periods and differences between cohorts limit causal interpretation and generalizability. Clinical usefulness remains unestablished.