Pitfalls in clinical trial design and methodology

Large clinical trials have become important tools for determining the benef its and risks of therapies for acute coronary syndromes. Understanding clin ical trial methodology is important both for trial design and interpretatio n of trial results. Conducting large trials, and overviews of large trials, involves the collaboration of many health professionals and experts in tri al design and methodology which, in turn, has major resource implications. Subjectivity may be introduced into clinical trials at many stages, and int erpretation of trials may be biased, depending on the original viewpoint of the investigator or the audience. The rationale for conducting large, rand omized trials involves the need to reduce bias and the requirement for larg e study populations to demonstrate small reductions when event rates are lo w. Potential sources of error in data interpretation are discussed. Overvie ws, or meta-analyses, of large trials addressing the same or similar questi ons may provide the best evidence for guiding the use of treatments, with t he caveat that publication bias favours the reporting of positive trials re sults.