The Lancet series on treating individuals
The authors discuss the determinants of external validity in trial publications and systematic reviews, present a checklist for clinicians, and make recommendations for consideration of external validity in the design and reporting of randomised controlled trials. Although randomised trials and systematic reviews provide reliable data on the effect of treatment, external validity is often poor. Peter Rothwell suggests that such studies should be designed and reported in a way that allows patients and clinicians to judge to whom the results can be reasonably applied.
The Lancet