Investigating patient exclusion bias in meta-analysis
Investigating patient exclusion bias in meta-analysis
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DOI：
10.1093/ije/dyh300
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发表时间：
2005-02-01
影响因子：
7.7
通讯作者：
Stewart, LA
中科院分区：
文献类型：
--
作者：
Tierney, JF;Stewart, LA
背景试验研究者经常将患者排除在试验分析之外，这可能会使治疗效果的估计产生偏倚。在一个荟萃分析结合这些估计可能会聚集任何这样的bias.Methods调查排除患者的试验如何影响试验和荟萃分析的结果，我们使用了14个荟萃分析的个体患者数据（IPD），解决癌症的治疗问题。其中包括133项随机对照试验（RCT）和21905例患者。我们探讨了排除是否与试验特征有关，并对排除的原因进行了分类。对于每个随机对照试验和荟萃分析，我们比较了所有随机患者的意向治疗分析的结果与基于研究者分析中包括的患者的分析结果。排除患者的试验往往比不排除患者的试验更古老，规模更大。大多数患者因不合格或方案违背而被排除。排除差异很大的荟萃分析，更多的患者倾向于被排除在治疗arm.Comparing试验分析有没有明确的迹象表明，排除患者改变的结果更有利于治疗或控制。然而，比较荟萃分析结果，有一种倾向，那些基于“纳入”的患者，有利于研究治疗（P = 0.03）。不一致的试验结果往往增加作为一个结果的调查员'exclusions.Conclusions试验，系统评价和荟萃分析可能容易与随机后排除患者的偏倚。在可能的情况下，在评估试验、系统评价和荟萃分析中的偏倚可能性时，应考虑此类排除的程度。理想情况下，试验、系统评价和荟萃分析应该基于所有随机化患者。
Background Trial investigators frequently exclude patients from trial analyses which may bias estimates of the effect of treatment. Combining these estimates in a meta-analysis could aggregate any such biases.Methods To investigate how excluding patients from trials can affect the results of both trials and meta-analyses, we used 14 meta-analyses of individual patient data (IPD) that addressed therapeutic questions in cancer. These included 133 randomized controlled trials (RCT) and 21 905 patients. We explored whether exclusions were related to trial characteristics and categorized the reasons for exclusions. For each RCT and meta-analysis, we compared results of an intention-to-treat analysis of all randomized patients with an analysis based on those patients included in the investigators' analysis.Results In all, 92 trials (69%) excluded between 0.3 and 38% of patients randomized. Trials excluding patients tended to be older and larger than those that did not. Most patients were excluded because of ineligibility or protocol violations. Exclusions varied substantially by meta-analysis, more patients tending to be excluded from the treatment arm. Comparing trial analyses there was no clear indication that exclusion of patients altered the results more in favour of either treatment or control. However, comparing meta-analysis results, there was a tendency for those based on 'included' patients to favour the research treatment (P = 0.03). Inconsistency of trial results was often increased as a result of the investigators' exclusions.Conclusions Trials, systematic reviews, and meta-analyses may be prone to bias associated with post-randomization exclusion of patients. Wherever possible, the level of such exclusions should be taken into account when assessing the potential for bias in trials, systematic reviews, and meta-analyses. Ideally, trials, systematic reviews, and meta-analyses should be based on all randomized patients.