Validity of studies suggesting preoperative chemotherapy for resectable thoracic esophageal cancer: A critical appraisal of randomized trials

Figure 1 Four steps to the analysis of validity of a systematic review according to our previous work[26]. We identified the endpoint of interest (overall survival) and selected the three most powerful studies addressing this endpoint on the basis of the assigned weights by the authors of the systematic review, as these studies contributed essentially to the positive result of the systematic review. We finally assessed the validity of these studies by using the CONSORT checklist.