Vist Gunn Elisabeth, Hagen Kåre Birger, Devereaux P J, Bryant Dianne, Kristoffersen Doris Tove, Oxman Andrew David
Norwegian Health Services Research Centre, PO Box 7004, 0130 Oslo, Norway.
BMJ. 2005 May 21;330(7501):1175. doi: 10.1136/bmj.330.7501.1175.
To systematically compare the outcomes of participants in randomised controlled trials (RCTs) with those in comparable non-participants who received the same or similar treatment.
Bibliographic databases, reference lists from eligible articles, medical journals, and study authors.
RCTs and cohort studies that evaluated the clinical outcomes of participants in RCTs and comparable non-participants who received the same or similar treatment.
Five RCTs (six comparisons) and 50 cohort studies (85 comparisons) provided data on 31,140 patients treated in RCTs and 20,380 comparable patients treated outside RCTs. In the five RCTs, in which patients were given the option of participating or not, the comparisons provided limited information because of small sample sizes (a total of 412 patients) and the nature of the questions considered. 73 dichotomous outcomes were compared, of which 59 reported no statistically significant differences. For patients treated within RCTs, 10 comparisons reported significantly better outcomes and four reported significantly worse outcomes. Significantly heterogeneity was found (I2 = 89%) among the comparisons of 73 dichotomous outcomes; none of our a priori explanatory factors helped explain this heterogeneity. The 18 comparisons of continuous outcomes showed no significant differences in heterogeneity (I2 = 0%). The overall pooled estimate for continuous outcomes of the effect of participating in an RCT was not significant (standardised mean difference 0.01, 95% confidence interval -0.10 to 0.12).
No strong evidence was found of a harmful or beneficial effect of participating in RCTs compared with receiving the same or similar treatment outside such trials.
系统比较随机对照试验（RCT）参与者与接受相同或相似治疗的可比非参与者的结局。
书目数据库、符合条件文章的参考文献列表、医学期刊及研究作者。
评估RCT参与者及接受相同或相似治疗的可比非参与者临床结局的RCT和队列研究。
五项RCT（六项比较）和50项队列研究（85项比较）提供了关于31140例在RCT中接受治疗的患者及20380例在RCT之外接受治疗的可比患者的数据。在五项患者可选择参与或不参与的RCT中，由于样本量小（共412例患者）及所考虑问题的性质，这些比较提供的信息有限。比较了73项二分结局，其中59项报告无统计学显著差异。对于在RCT中接受治疗的患者，10项比较报告结局显著更好，4项报告结局显著更差。在73项二分结局的比较中发现显著异质性（I² = 89%）；我们预先设定的解释因素均无法解释这种异质性。18项连续性结局的比较显示异质性无显著差异（I² = 0%）。参与RCT对连续性结局影响的总体合并估计不显著（标准化均数差0.01，95%置信区间 -0.10至0.12）。
未发现有力证据表明参与RCT与在这类试验之外接受相同或相似治疗相比有有害或有益影响。
