Cole Graham D, Nowbar Alexandra N, Mielewczik Michael, Shun-Shin Matthew J, Francis Darrel P
International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College London W2 1LA, UK
International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College London W2 1LA, UK.
BMJ. 2015 Sep 20;351:h4708. doi: 10.1136/bmj.h4708.
To compare the frequency of discrepancies in retracted reports of clinical trials with those in adjacent unretracted reports in the same journal.
Blinded case-control study.
Journals in PubMed.
50 manuscripts, classified on PubMed as retracted clinical trials, paired with 50 adjacent unretracted manuscripts from the same journals. Reports were randomly selected from PubMed in December 2012, with no restriction on publication date. Controls were the preceding unretracted clinical trial published in the same journal. All traces of retraction were removed. Three scientists, blinded to the retraction status of individual reports, reviewed all 100 trial reports for discrepancies. Discrepancies were pooled and cross checked before being counted into prespecified categories. Only then was the retraction status unblinded for analysis.
Total number of discrepancies (defined as mathematically or logically contradictory statements) in each clinical trial report.
Of 479 discrepancies found in the 100 trial reports, 348 were in the 50 retracted reports and 131 in the 50 unretracted reports. On average, individual retracted reports had a greater number of discrepancies than unretracted reports (median 4 (interquartile range 2-8.75) v 0 (0-5); P<0.001). Papers with a discrepancy were significantly more likely to be retracted than those without a discrepancy (odds ratio 5.7 (95% confidence interval 2.2 to 14.5); P<0.001). In particular, three types of discrepancy arose significantly more frequently in retracted than unretracted reports: factual discrepancies (P=0.002), arithmetical errors (P=0.01), and missed P values (P=0.02). Results from a retrospective analysis indicated that citations and journal impact factor were unlikely to affect the result.
Discrepancies in published trial reports should no longer be assumed to be unimportant. Scientists, blinded to retraction status and with no specialist skill in the field, identify significantly more discrepancies in retracted than unretracted reports of clinical trials. Discrepancies could be an early and accessible signal of unreliability in clinical trial reports.
比较同一期刊中撤稿的临床试验报告与相邻未撤稿报告中的差异出现频率。
双盲病例对照研究。
PubMed中的期刊。
50篇在PubMed上分类为撤稿的临床试验手稿，与同一期刊中50篇相邻的未撤稿手稿配对。2012年12月从PubMed中随机选取报告，对发表日期无限制。对照为同一期刊中之前发表的未撤稿临床试验。撤稿的所有痕迹均已去除。三位对各报告撤稿状态不知情的科学家审查了所有100篇试验报告以查找差异。差异汇总并交叉核对后再归入预先设定的类别。只有在这时才解除撤稿状态的盲态进行分析。
每份临床试验报告中的差异总数（定义为数学或逻辑上相互矛盾的陈述）。
在100篇试验报告中发现479处差异，其中348处在50篇撤稿报告中，131处在50篇未撤稿报告中。平均而言，单个撤稿报告中的差异数量多于未撤稿报告（中位数4（四分位间距2 - 8.75）对0（0 - 5）；P<0.001）。有差异的论文比无差异的论文更有可能被撤稿（比值比5.7（95%置信区间2.2至14.5）；P<0.001）。特别是，三种类型的差异在撤稿报告中出现的频率显著高于未撤稿报告：事实性差异（P = 0.002）、算术错误（P = 0.01）和遗漏P值（P = 0.02）。回顾性分析结果表明，引用次数和期刊影响因子不太可能影响结果。
不应再假定已发表试验报告中的差异不重要。对撤稿状态不知情且在该领域无专业技能的科学家发现，撤稿的临床试验报告中的差异明显多于未撤稿报告。差异可能是临床试验报告不可靠的一个早期且易于察觉的信号。
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