Cost-Effectiveness of Interventions Addressing Loneliness Among Adults: A Systematic Literature Review.

Objectives: Loneliness and social isolation are major public health concerns that contribute to numerous health consequences. Although many interventions effectively reduce loneliness and social isolation, their cost-effectiveness remain unclear. This study aimed to evaluate and consolidate evidence on the cost-effectiveness of interventions addressing loneliness or social isolation.

Methods: We conducted a systematic literature review of studies published until March 2024. A narrative synthesis of the selected studies was conducted to assess whether interventions for adults >18 years old were cost-effective, and we identified and discussed probable factors affecting cost-effectiveness. We assessed the reporting quality of the selected studies using the Consolidated Health Economic Evaluation Reporting Standards 2022.

Results: We included 16 studies covering 18 distinct interventions. Group-based interventions addressing loneliness and/or social isolation appeared generally more likely to be cost-effective compared with individual-based interventions, as were those explicitly targeting lonely individuals and with longer time horizons. Most studies included a societal perspective (8 studies, 10 interventions) and used quality-adjusted life-years (11 interventions). A total of 8 interventions were reported to be cost-effective. Overall, the reporting quality was judged satisfactory; however, none of the studies incorporated equity aspects, ie, distributional cost-effectiveness analysis.

Conclusions: Group-based interventions appear generally cost-effective in reducing loneliness despite heterogeneities among studies. However, more research is required with homogenous methodology, for example, societal perspective and longer time horizon before routine implementation.