Clinical Trials

❘❙❚■ Chapter 37 | Critical Appraisal of a Report3. Did patient selection particularly influence the results?If, after scanning the abstract, you decide to interrogate the paper further, it isuseful to focus on patient selection criteria before proceeding to the results.No trial can be properly evaluated without a detailed understanding of the studypopulation, but authors often fail to adequately define and account for the types ofsubjects finally recruited to a study. The team designing the trial has to find theproper balance between restricting eligibility in order to obtain a relatively uniformgroup of subjects and minimizing exclusion criteria so as to make the resultsrelevant to more patients. Many trials keep a screening register or log of studyeligiblepatients, as well as a log of those patients finally randomized. Both of thesefigures should be reported in the study manuscript. The ratio of patients screenedto those recruited can often suggest whether the inclusion/exclusion criteria werebroad enough to capture a large proportion of all patients with the disease.Consider the AWESOME (Angina With Extremely Serious Operative MortalityEvaluation) clinical trial, which was designed to compare long-term survival inpatients with medically refractory myocardial ischemia and a high risk of adverseoutcomes with either a surgical revascularization (coronary artery bypass grafting)or a percutaneous intervention strategy, including stents [8,9]. This trial screened22,662 patients, but randomized only 454, suggesting that the study focused ononly a very specific subgroup of patients with coronary artery disease. Therefore,the results of this study are relevant to only a small cohort of all ischemic patients,and cannot be easily extrapolated to daily practice.4. What do the recruitment rate and timing of publication tell us?It is interesting to note when patients were recruited and when the study completedenrollment. If recruitment rates were much slower than the expected presentationrate of similar patients in normal practice, one might discuss the following points:• Were the entry criteria too narrow, making recruitment difficult?• Was the treatment protocol overly complicated, discouraging recruitment?• Were the financial incentives for patient recruitment important?Financial incentives are usually unnecessary if the study addressesan issue that is important to both patients and clinicians.• Were the correct centers chosen to recruit for this study, or wasthe subject of little interest to recruiting centers?• Was recruitment slowed by an interim amendment to the protocolrequested by the data and safety monitoring board, suggestingsafety or statistical concerns at an early stage of the study?430