summary
background In the debate about evidence-based psychotherapy it is often assumed that randomised controlled trials (rct's) have a limited generalisability. Among the reasons for this assumption are the strict exclusion criteria which rule out patients with comorbidity or multiple diagnoses.
aim To investigate whether these strict exclusion criteria do effect the generalisability of rct's.
method Narrative overview of the research literature on psychotherapy.
results We found that the exclusion criteria in fact have less effect than expected on the generalisability.
conclusion Most patients from clinical practice can indeed be included in a rct. Recent rct's also include many patients with comorbidity.