ObjectivesTo explore the statistical performance of different methods for meta-analysis of single rates with zero events so as to provide evidence for selecting meta-analysis methods in evidence-based research.MethodsThrough Monte-Carlo simulations, we evaluated the performance of various transformation and correction methods for meta-analysis of single rates with zero events, considering the point estimate bias, confidence interval coverage and width.ResultsWhen the overall event rate was above 30%, all methods showed good statistical performance. As the event rate dropped, log, logit, and arcsine transformations could still maintain good performance. However, when the event rate was less than 5%, only Freeman-Tukey transformation showed excellent performance.ConclusionsThe meta-analysis of single rate based on Freeman-Tukey transformation is robust, and should be recommended as the preferable choice of meta-analysis of single rate with zero events.
ObjectiveTo analyze the current status of the application of randomization methods in randomized controlled trials (RCTs) which have been published in New England Journal of Medicine (NEJM).MethodsRCTs published by NEJM in 2018 were searched and collected. The characteristics of clinical trial design elements and the application status of randomization methods were comprehensively analyzed to distinguish blind trial and non-blind trial, and characteristics of application of randomization methods and selection of allocation concealment mechanisms of non-blind trials were summarized.ResultsA total of 151 RCTs were published in NEJM in 2018, in which blinded trials and non-blinded trials accounted for 75 (49.67%) and 76 (50.33%), respectively. 34 (22.52%) RCTs did not report specific randomization methods, and the remaining 117 (77.48%) reported. Among the latter, stratified block randomization accounted for the main body (72.65%), followed by block randomization (11.11%), minimization method (9.40%), simple randomization method (4.27%) and the others. There was no significant difference in the proportion of reporting or using randomization methods between blind and non-blind trials (P>0.05). In 76 non-blind trials, 38 (50.00%) clearly reported the concealment method of random allocation, among which 37 used the central randomization (97.37%) and 1 used envelope method (2.63%).ConclusionsThe current RCTs published in NEJM still have problems in the selection of randomization methods to be optimized and the transparency of randomization reporting to be improved.