Abstract
There is a treatment gap for Common Mental Disorders (CMDs) such as anxiety, depression, and post-traumatic stress disorder (PTSD), as well as non-specific psychological distress (NPD) in low- and middle-income countries (LAMIC), due to the lack of available clinicians and locally appropriate interventions. Task-shifting using non-specialist providers (NSP) and transdiagnostic approaches may address this. Transdiagnostic approaches can be effective at treating CMDs and NPD in high-income countries (HIC), but currently, there is no comprehensive synthesis of evidence regarding their effectiveness in LAMICs. This review addressed this gap by examining the effectiveness of transdiagnostic psychological interventions for symptoms of CMDs and NPD delivered by NSPs in LAMICs. Three databases were searched (Embase, PsycInfo, and PubMed). Hedge's g's were calculated using random-effect models to correct for small sample bias. Twenty-one transdiagnostic interventions across 20 studies were included. Moderate reductions at posttreatment were found in psychological distress (g = -0.64; 95% CI: -0.81 to -0.46), symptoms of anxiety (g = -0.61; 95% CI: -0.80 to -0.42), depression (g = -0.59; 95% CI: -0.75 to -0.44), and PTSD/trauma (g = -0.38; 95% CI: -0.59 to -0.16), with significant small reductions maintained at follow-up ranging from 13 to 26 weeks for NPD (SMD = - 0.37; 95% CI: -0.57 to -0.17), anxiety (g = - 0.41; 95% CI: -0.91 to 0.09), depression (g = -0.38; 95% CI: -0.59 to -0.16), and trauma symptoms (g = -0.23; 95% CI: -0.42 to -0.05). These findings are important and suggest that transdiagnostic approaches delivered by NSPs are effective at treating symptoms of CMDs and NPD in LAMICs. Future research should consider comparing task-shifting approaches with disorder-specific interventions and explore the effectiveness of longer sessions across various mental health conditions.