부산대학교 도서관

Inadequate concealment of patient treatment allocation during randomized, controlled trials appears to lead to unreliable results. Randomized, controlled trials are used to evaluate drug therapy or other treatments. Thirty-three meta-analyses of the design of 250 controlled trials were analyzed. In 79 trials researchers judged that adequate steps were taken to conceal treatment allocation from participants. In 21 trials, inadequate steps were taken and in 150 trials researchers were unable to determine if steps to conceal treatment allocation were adequate. Significantly larger estimates of treatment effects occurred in trials in which concealment was unclear or inadequate than in trials judged to have provided adequate concealment. When evaluating studies, researchers should carefully assess whether biases in comparison groups exist.
Objective. - To determine if inadequate approaches to randomized controlled trial design and execution are associated with evidence of bias in estimating treatment effects. Design. - An observational study in which we assessed the methodological quality of 250 controlled trials from 33 meta-analyses and then analyzed, using multiple logistic regression models, the associations between those assessments and estimated treatment effects. Data Sources. - Meta-analyses from the Cochrane Pregnancy and Childbirth Database. Main Outcome Measures. - The associations between estimates of treatment effects and inadequate allocation concealment, exclusions after randomization, and lack of double-blinding. Results. - Compared with trials in which authors reported adequately concealed treatment allocation, trials in which concealment was either inadequate or unclear (did not report or incompletely reported a concealment approach) yielded larger estimates of treatment effects (P