Generalising the results of trials to clinical practice

Randomised controlled trials should be the basis for developing clinical guidelines and for decisions about individual patient management. They should also inform public health policy. However, their capacity to fulfil these roles will depend on how closely a trial’s participants reflect the general population of patients with the disorder that has been investigated. The extent to which a trial’s findings are relevant to the broader population of patients with the disorder is referred to as the trial’s generalisability, or external validity. The CONSORT statement refers to generalisability under Item 21 (Box 1).1 Well-written reports should discuss the various factors that influence the generalisability of the trial’s findings. Julian and Pocock have proposed a checklist of questions to assist with this assessment (see Box 2).2