Fig 1.
A total of 36 studies were identified for inclusion in the reviews, after a two-stage screening process. Twenty-seven studies among them were included in meta-analyses.
Table 1.
Characteristics of 36 studies included in this systematic review.
Fig 2.
Forest plots and pooled estimates for hazard ratios of social isolation for all-cause mortality.
The random effects weighted average hazard ratios of social isolation for all-cause mortality is 1.33 (95% CI); 1.26–1.41) with substantial heterogeneity (heterogeneity: Chi² = 112.51, P < 0.00001, I² = 76%).
Fig 3.
Forest plots and pooled estimates hazard ratios of social isolation for all-cause mortality are shown separately for different social isolation assessment tools.
The hazard ratio among the studies using the Berkman-Syme Social Network Index to assess social isolation is 1.35 (95% CI; 1.24–1.47) with substantial heterogeneity (heterogeneity: Chi² = 39.10, P < 0.0001, I² = 74%) whereas that among the remainders is 1.33 (95% CI; 1.23–1.44) with substantial heterogeneity (heterogeneity: Chi² = 60.22, P < 0.00001, I² = 73%).