How to perform a critical analysis of a randomised controlled trial

Given the large amount of medical literature of varying methodological quality, care must be taken when translating the results of randomised controlled trials into clinical practice. To assist in this translation process, we provide a method that involves answering three main questions: ‘Can I trust the results?’ ‘How do I understand the results?’ and ‘To whom do the results apply?’ To answer the first question, we describe important items that help in judging the reliability of the findings. For the second question, we address the clinical and statistical significance of results by looking at the size and precision of the effect. Finally, we raise the issue of external validity and of reporting adverse effects to determine which patients may best benefit from the new intervention.