PDF(Pubmed)
Abstract：
Our study aimed to establish the risk of selection bias in randomized controlled trials (RCT) that were overall rated as having \"low bias\" risk according to Cochrane\'s Risk of Bias, version 2 (RoB 2) tool. A systematic literature search of current systematic reviews of RCTs was conducted. From the identified reviews, RCTs with overall \"high bias\" and \"low bias\" RoB 2 risk ratings were extracted. All RCTs were statistically tested for selection bias risk. From the test results, true positive, true negative, false positive, or false negative ratings were established, and the false omission rate (FOR) with a 95% confidence interval (CI) was computed. Subgroup analysis was conducted by computing the negative likelihood ratio (-LR) concerning RoB 2 domain 1 ratings: bias arising from the randomization process. A total of 1070 published RCTs (median publication year: 2018; interquartile range: 2013-2020) were identified and tested. We found that 7.61% of all \"low bias\" (RoB 2)-rated RCTs were of high selection bias risk (FOR 7.61%; 95% CI: 6.31%-9.14%) and that the likelihood for high selection bias risk in \"low bias\" (RoB 2 domain 1)-rated RCTs was 6% higher than that for low selection bias risk (-LR: 1.06; 95% CI: 0.98-1.15). These findings raise issues about the validity of \"low bias\" risk ratings using Cochrane\'s RoB 2 tool as well as about the validity of some of the results from recently published RCTs. Our results also suggest that the likelihood of a \"low bias\" risk-rated body of clinical evidence being actually bias-free is low, and that generalization based on a limited, pre-specified set of appraisal criteria may not justify a high level of confidence that such evidence reflects the true treatment effect.
摘要：
我们的研究旨在建立随机对照试验（RCT）中的选择偏倚风险，根据Cochrane的“偏倚风险”，这些试验总体上被评为具有“低偏倚”风险。版本2（RoB2）工具。对当前RCT的系统评价进行了系统的文献检索。从确定的评论中，提取总体“高偏倚”和“低偏倚”RoB2风险评级的随机对照试验。对所有RCT进行选择偏倚风险的统计学检验。从测试结果来看,真积极，正负,假阳性,或者建立了假阴性评级，并以95%的置信区间(CI)计算误报率(FOR)。通过计算RoB2域1评分的负似然比（-LR）进行亚组分析：随机化过程引起的偏倚。确定并测试了总共1070个已发表的RCT（中位发表年份：2018年；四分位数范围：2013-2020年）。我们发现，所有“低偏倚”（RoB2）级RCT中有7.61％具有高选择偏倚风险（FOR7.61％；95％CI：6.31％-9.14％），并且“低偏倚”（RoB2域1）级RCT中高选择偏倚风险的可能性比低选择偏倚风险的高6％（-LR：1.06；95％CI：0.98）。这些发现提出了有关使用Cochrane的RoB2工具进行“低偏倚”风险评级的有效性以及最近发表的RCT的一些结果的有效性的问题。我们的结果还表明，“低偏倚”风险评估的临床证据实际上没有偏倚的可能性很低，这种概括基于有限的，预先指定的一套评估标准可能无法证明这些证据反映了真实的治疗效果。
