An Updated Systematic Literature Review of the Economic Costs of Loneliness and Social Isolation and the Cost Effectiveness of Interventions

Purpose There has been growing interest in understanding the economic impacts of loneliness and social isolation. This study updates a previous review on the economic costs of loneliness and social isolation and the cost effectiveness of related interventions. Methods We conducted a systematic search in the MEDLINE, PsycInfo, CINAHL, and Embase databases from 2018 to 13 August 2024, supplemented by a search of the grey literature. Studies included cost-of-illness studies, economic evaluations, and social return on investment (SROI) analyses published in the English language. All studies were evaluated for quality and summarised using a narrative approach. Costs reported were converted into US$, year 2024 values. Results In total, 15 studies were included: six cost-of-illness studies, four economic evaluations, and five SROI studies. Cost-of-illness studies primarily examined healthcare and productivity costs. All but one study reported excess costs linked to loneliness and social isolation, ranging from US$2 billion to US$25.2 billion per annum. Among four economic evaluations, three were model-based cost-utility or cost-effectiveness analyses (targeting older adults and the general population), and one was trial based (focusing on low-income individuals with health issues). One study found an intervention cost effective, whereas cost-effectiveness probabilities in others ranged from 54% to 68%. One study concluded that an intervention to reduce severe loneliness in older adults was cost effective but unlikely to be cost saving. All SROI studies reported positive returns, with SROI ratios ranging from US$2.28 to US$13.72. Conclusion This review highlights additional evidence on the economic burden of loneliness and social isolation. Future research should explore broader cost impacts beyond healthcare and expand cost-effectiveness studies to younger populations.