Global Trends and Disparities in Social Isolation.

Importance: Social isolation is consequential for human health and well-being. However, global trends and trends across countries, regions, and socioeconomic strata remain inadequately characterized, limiting targeted policy responses. Objectives: To quantify global changes in social isolation from 2009 to 2024 across within-country income groups and evaluate cross-country and regional variation in isolation levels and trends. Design, Setting, and Participants: This cross-sectional study used data from 2009 to 2024 from the Gallup World Poll, a globally representative repeated cross-sectional survey with consistent methodology across more than 150 countries. A random sample of approximately 1000 adults (age ≥15 years) within each country was selected at each annual assessment. Global trends in isolation were examined for the full sample and for top and bottom income groups, defined within each country. Main Outcomes and Measures: The prevalence of social isolation at each time point within each country was assessed as the proportion of respondents who answered "no" to having relatives or friends available to help in times of trouble. Household income was assessed in local currency and coded into 5 quintiles. Results: The study findings are based on data from 2 483 935 person-level assessments (mean [SD] age, 41.7 [17.9] years; 53.1% women) across 16 time points and 159 countries. Prepandemic global mean isolation levels were stable. A marked increase in isolation occurred between 2019 and 2020, concurrent with the onset of the COVID-19 pandemic, and was disproportionately seen in lower-income groups (β = 2.6 percentage points [95% CI, 0.9-4.4 percentage points]; P = .003; an 11.0% increase). From 2020 to 2024, isolation continued to increase, with steeper increases among higher-income groups (β = 1.9 [95% CI, 0.7-3.1]; P < .001; a 12.3% increase). The global prevalence of social isolation increased by 13.4% from 2009 to 2024 (from 19.2% [95% CI, 17.3%-21.6%] to 21.8% [95% CI, 19.4%-24.2%]), with the entire increase occurring after 2019. The disparity in isolation prevalence between high- and low-income groups peaked in 2020: 26.4% (95% CI, 23.6%-29.2%) of lower income groups were isolated vs 15.6% (95% CI, 13.6%-17.7%) of higher income groups. By 2024, global isolation was 2.6 percentage points (95% CI, 0.7-4.5 percentage points) above prepandemic levels and the income disparity was 8.6 percentage points (95% CI, 5.1-12.1 percentage points). A total of 54 countries experienced worsening isolation and widening disparities, while 41 saw improvements. Conclusions and Relevance: In this cross-sectional study, social isolation was found to have increased globally after the COVID-19 pandemic, with the initial increase disproportionately seen in lower-income populations and subsequent increases broadening across socioeconomic strata. Targeted interventions for vulnerable groups and research examining country-level policies are urgently needed to mitigate high isolation levels and reduce inequities.