Zeas-Sigüenza, AnandaVoldstad, AndreasRuisoto, PabloGanho-Ávila, AnaGuiomar, RaquelCacho, RaúlMuntané Isart, FerranBenach, Joan2025-10-072025-10-072025Zeas-Sigüenza A, Voldstad A, Ruisoto P, Ganho-Ávila A, Guiomar R, Cacho R, et al. Loneliness as a public health challenge: a systematic review and meta-analysis to inform policy and practice. Eur J Investig Health Psychol Educ. 2025 Jul;15(7):131. DOI: 10.3390/ejihpe150701312254-9625http://hdl.handle.net/10230/71419Loneliness is a recognized public health risk factor associated with increased morbidity and mortality. However, the effectiveness of interventions targeting loneliness remains unclear—particularly in relation to baseline severity. This systematic review and meta-analysis assessed intervention effectiveness and the influence of baseline severity and intervention characteristics. A total of 25 studies were included, of which 16 randomized controlled trials (RCTs; k = 21) were meta-analyzed. Interventions produced a moderate pooled effect at post-intervention (Hedge’s g = 0.65, 95% CI [0.05, 1.26], p = 0.037), though with high heterogeneity. Sensitivity analyses confirmed a moderate effect (g = 0.55, 95% CI [0.22, 0.88], p = 0.003). Higher baseline loneliness predicted greater intervention effects (b = 0.04, 95% CI [0.02, 0.07], Z = 3.36, p < 0.001), with cognitive-behavioral therapy (CBT) showing the largest effect size (g = 0.73). No significant effects were observed at follow-up. These findings underscore the need for dual strategies: targeted psychological interventions (e.g., CBT) for individuals with severe loneliness, and universal, context-based approaches for the broader population. This aligns with Geoffrey Rose’s distinction between individual-level treatment and population-level prevention and highlights the urgency of embedding loneliness interventions into public health frameworks and policy agendas focused on promoting social connectedness and equity.application/pdfeng© 2025 by the authors. Published by MDPI on behalf of the University Association of Education and Psychology. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).info:eu-repo/semantics/articlehttp://dx.doi.org/10.3390/ejihpe15070131LonelinessMeta-analysisIntervention efficacyBaseline severityPublic healthinfo:eu-repo/semantics/openAccess