BACKGROUND Assessing the risk of bias (RoB) in included studies is one of the key methodological aspects of systematic reviews. Cochrane systematic reviews appraise RoB of randomised controlled trials (RCTs) with the Cochrane RoB tool. Detailed instructions for using the Cochrane RoB tool are provided in the Cochrane Handbook for Systematic Reviews of Interventions (The Cochrane Handbook). The purpose of this study was to analyse whether Cochrane authors use adequate judgments about the RoB for random sequence generation of RCTs included in Cochrane reviews. METHODS We extracted authors' judgments (high, low or unclear RoB) and supports for judgments (comments accompanying judgments which explain the rationale for a judgment) for random sequence generation of included RCTs from RoB tables of Cochrane reviews using automated data scraping. We categorised all supporting comments, analysed the number and type of various supporting comments and assessed adequacy of RoB judgment for randomisation in line with recommendations from the Cochrane Handbook. RESULTS We analysed 10,103 RCTs that were included in 704 Cochrane reviews. For 5,706 RCTs, randomisation was not described, but for the remaining RCTs, it was indicated that randomisation was performed using computer/software/internet (N = 2,850), random number table (N = 883), mechanical method (N = 359) or it was incomplete/inappropriate (N = 305). Overall, 1,220/10,103 trials (12%) did not have a RoB judgment in line with Cochrane Handbook guidance about randomisation. The highest proportion of misjudgements was found for trials with high RoB (28%), followed by those with low (20%) or unclear (3%). Therefore, one in eight judgments for the analysed domain in Cochrane reviews was not in line with Cochrane Handbook, and one in four if the judgment was "high risk". CONCLUSION Authors of Cochrane reviews often make judgments about the RoB related to random sequence generation that are not in line with instructions given in the Cochrane Handbook, which compromises the reliability of the systematic reviews. Our results can help authors of both Cochrane and non-Cochrane reviews which use Cochrane RoB tool to avoid making common mistakes when assessing RoB in included trials.

中文翻译：

---

Cochrane系统评价中随机序列产生的偏倚判断风险常常与《 Cochrane手册》不符。

背景技术评估纳入研究中的偏倚风险（RoB）是系统评价的关键方法论方面之一。Cochrane系统评价使用Cochrane RoB工具评估随机对照试验（RCT）的RoB。《 Cochrane干预措施的系统评价手册》（《 Cochrane手册》）中提供了使用Cochrane RoB工具的详细说明。这项研究的目的是分析Cochrane作者是否对RoB进行了充分的判断，以用于Cochrane综述中所包括的RCT的随机序列生成。方法我们提取了作者的判断（RoB高，低或不清楚），并支持使用自动数据抓取从Cochrane评价的RoB表中随机生成随机RCT的判断（伴随判断的理由的判断附带的评论）。我们对所有支持意见进行了分类，分析了各种支持意见的数量和类型，并根据Cochrane手册中的建议评估了RoB判断随机化的充分性。结果我们分析了704份Cochrane评估中纳入的10103篇RCT。对于5,706个RCT，未描述随机化，但对于其余RCT，表明使用计算机/软件/互联网（N = 2,850），随机数表（N = 883），机械方法（N = 359）进行随机化或不完整/不合适（N = 305）。总体而言，1,220 / 10,103试验（12％）的RoB判断与Cochrane手册中有关随机分组的指导意见不一致。RoB较高的试验（28％）的错误判断比例最高，其次是低（20％）或不清楚（3％）的错误判断。所以，对于Cochrane评论中所分析的领域，八分之一的判断与《 Cochrane手册》不一致，如果该判断为“高风险”，则为四分之一。结论Cochrane评价的作者经常对与随机序列生成相关的RoB做出判断，这与《 Cochrane手册》中给出的说明不一致，这损害了系统评价的可靠性。我们的结果可以帮助使用Cochrane RoB工具的Cochrane和非Cochrane评价的作者避免在纳入试验中评估RoB时犯常见的错误。结论Cochrane评价的作者经常对与随机序列生成相关的RoB做出判断，这与《 Cochrane手册》中给出的说明不一致，这损害了系统评价的可靠性。我们的结果可以帮助使用Cochrane RoB工具的Cochrane和非Cochrane评价的作者避免在纳入试验中评估RoB时犯常见的错误。结论Cochrane评价的作者经常对与随机序列生成相关的RoB做出判断，这与《 Cochrane手册》中给出的说明不一致，这损害了系统评价的可靠性。我们的结果可以帮助使用Cochrane RoB工具的Cochrane和非Cochrane评价的作者避免在纳入试验中评估RoB时犯常见的错误。