Treatment and prevention of common mental health problems: comparisons of four low-intensity interventions in a community outpatient setting

<b>Objective:</b> Low-intensity interventions based on cognitive behavioral therapy are often used to scale up treatment volumes for common mental health problems. However, mode of delivery could have implications for outcomes. <b>Methods:</b> This was an observational study of adults seeking treatment in a naturalistic setting of outpatient community mental health services (<i>N</i> = 897). Depending on their problem description, patients were allocated to four different low-intensity interventions: group psychoeducation, group therapies, guided self-help, and one-to-one consultations. Pre-to posttreatment changes on the Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), and Work- and Social Adjustment Scale (WSAS) were estimated using linear mixed-effects models and propensity score weighted analyses. <b>Results:</b> The proportion of patients achieving clinically significant change (CSC), and time used to achieve CSC varied between interventions, with guided self-help showing the highest rates of CSC (53-66%, <i>d</i> = 0.62-1.04) and group psychoeducation being most time-effective intervention. For subclinical patients, guided self-help had the lowest rates of reliable deterioration (0-8%). <b>Conclusion:</b> Low-intensity interventions within routine community mental health care have acceptable outcomes. Mode of delivery appears to be important for rates of CSC, therapist time investment, and prevention of deterioration. Future studies should investigate which low-intensity interventions work for whom.