Are randomised controlled trials the only gold that glitters?

The intention of evidence-based mental The intention of evidence-based mental health care is that every clinical decision health care is that every clinical decision should be underpinned by research evidence. should be underpinned by research evidence. It is therefore clearly important to agree what It is therefore clearly important to agree what constitutes evidence. A hierarchy of evidence constitutes evidence. A hierarchy of evidence is widely used, with systematic reviews and is widely used, with systematic reviews and meta-analyses being the strongest, followed meta-analyses being the strongest, followed by randomised controlled trials (RCTs) with by randomised controlled trials (RCTs) with definitive results, RCTs with non-definitive definitive results, RCTs with non-definitive results, cohort studies, casecontrol studies, results, cohort studies, casecontrol studies, cross-sectional surveys and case reports. cross-sectional surveys and case reports. Thus, good quality evidence is equated with Thus, good quality evidence is equated with RCTs, which can be grouped using meta-RCTs, which can be grouped using metaanalyses and systematic reviews. Can RCTs analyses and systematic reviews. Can RCTs provide all the necessary evidence? Three provide all the necessary evidence? Three conceptual issues will be considered: group-conceptual issues will be considered: grouplevel research designs, generalisation and level research designs, generalisation and bias in the evidence base. bias in the evidence base.