The prevalence of loneliness across 113 countries: systematic review and meta-analysis

Abstract

Objectives: To identify data availability, gaps, and patterns for population level prevalence of loneliness globally, to summarise prevalence estimates within World Health Organization regions when feasible through meta-analysis, and to examine temporal trends of loneliness in countries where data exist.

Design: Systematic review and meta-analysis.

Data sources: Embase, Medline, PsycINFO, and Scopus for peer reviewed literature, and Google Scholar and Open Grey for grey literature, supplemented by backward reference searching (to 1 September 2021) ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Observational studies based on nationally representative samples (n≥292), validated instruments, and prevalence data for 2000-19. Two researchers independently extracted data and assessed the risk of bias using the Joanna Briggs Institute checklist. Random effects meta-analysis was conducted in the subset of studies with relatively homogeneous research methods by measurement instrument, age group, and WHO region.

Results: Prevalence data were available for 113 countries or territories, according to official WHO nomenclature for regions, from 57 studies. Data were available for adolescents (12-17 years) in 77 countries or territories, young adults (18-29 years) in 30 countries, middle aged adults (30-59 years) in 32 countries, and older adults (≥60 years) in 40 countries. Data for all age groups except adolescents were lacking outside of Europe. Overall, 212 estimates for 106 countries from 24 studies were included in meta-analyses. The pooled prevalence of loneliness for adolescents ranged from 9.2% (95% confidence interval 6.8% to 12.4%) in South-East Asia to 14.4% (12.2% to 17.1%) in the Eastern Mediterranean region. For adults, meta-analysis was conducted for the European region only, and a consistent geographical pattern was shown for all adult age groups. The lowest prevalence of loneliness was consistently observed in northern European countries (2.9%, 1.8% to 4.5% for young adults; 2.7%, 2.4% to 3.0% for middle aged adults; and 5.2%, 4.2% to 6.5% for older adults) and the highest in eastern European countries (7.5%, 5.9% to 9.4% for young adults; 9.6%, 7.7% to 12.0% for middle aged adults; and 21.3%, 18.7% to 24.2% for older adults).

Conclusion: Problematic levels of loneliness are experienced by a substantial proportion of the population in many countries. The substantial difference in data coverage between high income countries (particularly Europe) and low and middle income countries raised an important equity issue. Evidence on the temporal trends of loneliness is insufficient. The findings of this meta-analysis are limited by data scarcity and methodological heterogeneity. Loneliness should be incorporated into general health surveillance with broader geographical and age coverage, using standardised and validated measurement tools.

Systematic review registration: PROSPERO CRD42019131448.

Fig 1

International estimates for prevalence of loneliness by age groups

Fig 2

Meta-analysis of loneliness prevalence using scale based measures (de Jong Gierveld Loneliness Scale, six item version, and University of California Los Angeles (UCLA) Loneliness Scale, three item version) in older adults (≥60 years). *Thresholds of five or six were applied. Generalised linear mixed effects models with binomial-normal distribution were used. Norway is included as part of western Europe owing to the lack of data from other northern European countries

Fig 3

Meta-analysis of loneliness prevalence based on single item measures in adolescents (12-17 years) by World Health Organization Africa region. Generalised linear mixed effects models with binomial-normal distribution were used

Fig 4

Meta-analysis of loneliness prevalence based on single item measures in adolescents (12-17 years) by World Health Organization The Americas region. Generalised linear mixed effects models with binomial-normal distribution were used

Fig 5

Meta-analysis of loneliness prevalence based on single item measures in adolescents (12-17 years) by World Health Organization Eastern Mediterrean and South-East Asia regions. Generalised linear mixed effects models with binomial-normal distribution were used

Fig 6

Meta-analysis of loneliness prevalence based on single item measures in adolescents (12-17 years) by World Health Organization Western Pacific region. Generalised linear mixed effects models with binomial-normal distribution were used

Fig 7

Meta-analysis of loneliness prevalence based on single item measures in young adults (18-29 years) in Europe. Generalised linear mixed effects models with binomial-normal distribution were used. *Unspecified recall period; past week otherwise. †Includes Israel. ‡Includes Georgia

Fig 8

Meta-analysis of loneliness prevalence based on single item measures in middle aged adults (30-59 years) in Europe. Generalised linear mixed effects models with binomial-normal distribution were used. *Unspecified recall period; past week otherwise

Fig 9

Meta-analysis of loneliness prevalence based on single item measures in older adults (≥60 years) in Europe. Generalised linear mixed effects models with binomial-normal distribution were used. *Includes Israel. †Includes Georgia. ‡Unspecified recall period; past week otherwise