Interpreting the evidence: choosing between randomised and non-randomised studies
Interpreting the evidence: choosing between randomised and non-randomised studies
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DOI：
10.1136/bmj.319.7205.312
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发表时间：
1999-07-31
影响因子：
105.7
通讯作者：
Bain, C
中科院分区：
文献类型：
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作者：
McKee, M;Britton, A;Bain, C
对医疗保健干预措施的评估可以将受试者随机分配到对照组，也可以不随机分配。在这两种设计中，有效性都存在潜在的威胁，这些威胁可能是外部的（它们在多大程度上适用于所有潜在的接受者）或内部的（观察到的效果的差异是否可以归因于干预的差异）。随机化应确保足够规模的对照组仅在相关干预措施的暴露程度上存在差异。然而，一些研究者认为，随机对照试验（RCTs）倾向于有意或无意地排除某些类型的患者，而这些患者的结果随后将适用于这些患者。此外，在非盲法试验中，治疗结果可能受到从业人员和患者对一种或另一种干预措施的偏好的影响。虽然非随机研究在招募方面选择性较低，但如果治疗与初始预后相关，则在分配时存在选择偏倚。
Evaluations of healthcare interventions can either randomise subjects to comparison groups, or not. In both designs there are potential threats to validity, which can be external (the extent to which they are generalisable to all potential recipients) or internal (whether differences in observed effects can be attributed to differences in the intervention). Randomisation should ensure that comparison groups of sufficient size differ only in their exposure to the intervention concerned. However, some investigators have argued that randomised controlled trials (RCTs) tend to exclude, consciously or otherwise, some types of patient to whom results will subsequently be applied. Furthermore, in unblinded trials the outcome of treatment may be influenced by practitioners’ and patients’ preferences for one or other intervention. Though non-randomised studies are less selective in terms of recruitment, they are subject to selection bias in allocation if treatment is related to initial prognosis.