Misery loves company: Predictors of treatment response to a loneliness intervention

Objective: The last 10 years have seen a surge of interest in loneliness and interventions to reduce it. However, there is little evidence regarding differential treatment effectiveness and predictors of treatment outcome. This paper aimed to investigate possible predictors of treatment response. Methods: We analysed data from two clinical trials of an evidence-based loneliness intervention: Groups 4 Health (G4H). Study 1 had 163 observations across two timepoints, n = 94; Study 2 had 297 observations across four timepoints; n = 84. Theorised predictors—symptom severity at baseline, program engagement, and demographic characteristics—were assessed for their effect on the primary outcome: loneliness. Results: Across both trials, participants with more severe baseline loneliness or social anxiety, or who attended more sessions, experienced greater improvement in loneliness. In Study 2, those with diagnosed mental illness or more severe baseline depression also tended to have better outcomes. There was no evidence that age, gender, or ethnicity predicted program efficacy. Conclusion: Overall, those with greater need—reflected in either severity of loneliness or psychological distress—tended to show greater improvement over time. This was due, in part, to greater engagement with the program among those who were lonelier. We discuss how loneliness interventions can be deployed most effectively to combat this profound public health challenge.