Impact evaluations of mental health programmes: the missing piece in global mental health

The past 10 years have witnessed a remarkable rise in the visibility of the field of global mental health, which applies the core principles of global health (improving health and equity in health for all people worldwide1) to mental health. The stated goal of global mental health is to reduce the burden of mental disorders using an evidence-based and human rights approach with a focus on low and middle income countries (LMIC) as this is where inequity in mental health treatment and care is the greatest.2 The field, as witnessed by the changing nature of papers published in this journal, has moved rapidly from research into the prevalence of and risk factors for mental disorders,3 ,4 to randomised controlled trials (RCTs) of interventions in low-resource settings.5 There is now a small but growing evidence base of RCTs of effective interventions for a range of mental disorders, largely delivered as psychological therapies by non-specialist health workers.6 This is complemented by a rich history of transcultural psychiatric research emphasising the need for locally adapted and culturally appropriate interventions, from which global mental health draws inspiration.7 The relative youth and fast-moving nature of the field means that these streams of research must continue informing each other for many years to come. For example: we lack even the most basic prevalence data from many LMIC to inform Global Burden of Disease estimates;8 interventions to combat social determinants and prevent mental disorders are poorly understood; many types of mental health interventions do not have proof of concept in low-resource settings; and we need to better understand how to adapt interventions with proof of concept to ensure they are culturally acceptable and effective in new settings. The critical missing piece is evidence of impact from real-world mental health programmes. …