Clinical Trials and Evidence-Based Medicine Unit, Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, University Campus, Ioannina, Greece.
BMJ. 2013 Feb 12;346:f707. doi: 10.1136/bmj.f707.
To compare treatment effects from randomised trials conducted in more developed versus less developed countries.
Meta-epidemiological study.
Cochrane Database of Systematic Reviews (August 2012).
Meta-analyses with mortality outcomes including data from at least one randomised trial conducted in a less developed country and one in a more developed country. Relative risk estimates of more versus less developed countries were compared by calculating the relative relative risks for each topic and the summary relative relative risks across all topics. Similar analyses were performed for the primary binary outcome of each topic.
139 meta-analyses with mortality outcomes were eligible. No nominally significant differences between more developed and less developed countries were found for 128 (92%) meta-analyses. However, differences were beyond chance in 11 (8%) cases, always showing more favourable treatment effects in trials from less developed countries. The summary relative relative risk was 1.12 (95% confidence interval 1.06 to 1.18; P<0.001; I(2)=0%), suggesting significantly more favourable mortality effects in trials from less developed countries. Results were similar for meta-analyses with nominally significant treatment effects for mortality (1.15), meta-analyses with recent trials (1.14), and when excluding trials from less developed countries that subsequently became more developed (1.12). For the primary binary outcomes (127 meta-analyses), 20 topics had differences in treatment effects beyond chance (more favourable in less developed countries in 15/20 cases).
Trials from less developed countries in a few cases show significantly more favourable treatment effects than trials in more developed countries and, on average, treatment effects are more favourable in less developed countries. These discrepancies may reflect biases in reporting or study design as well as genuine differences in baseline risk or treatment implementation and should be considers when generalising evidence across different settings.
比较在较发达国家和较不发达国家进行的随机试验的治疗效果。
meta 流行病学研究。
Cochrane 系统评价数据库（2012 年 8 月）。
对死亡率结局的 meta 分析，包括至少一项在较不发达国家和一项在较发达国家进行的随机试验的数据。通过计算每个主题的相对相对风险和所有主题的汇总相对相对风险，比较较发达国家和较不发达国家的相对风险估计值。对每个主题的主要二分类结局进行了类似的分析。
有 139 项死亡率结局的 meta 分析符合条件。在 128 项 meta 分析（92%）中，没有发现较发达国家和较不发达国家之间存在显著差异。然而，在 11 项 meta 分析（8%）中，差异超出了偶然范围，总是显示出来自较不发达国家的试验有更有利的治疗效果。汇总相对相对风险为 1.12（95%置信区间 1.06 至 1.18；P<0.001；I(2)=0%），提示来自较不发达国家的试验的死亡率有更有利的影响。对于死亡率有显著治疗效果的 meta 分析（1.15）、最近试验的 meta 分析（1.14）以及排除来自较不发达国家的试验的 meta 分析（这些试验后来变得更发达）（1.12），结果相似。对于主要的二分类结局（127 项 meta 分析），20 个主题的治疗效果差异超出了偶然范围（在 15/20 个病例中，来自较不发达国家的治疗效果更有利）。
在少数情况下，来自较不发达国家的试验比来自较发达国家的试验显示出显著更有利的治疗效果，并且平均而言，较不发达国家的治疗效果更有利。这些差异可能反映了报告或研究设计方面的偏差，以及基线风险或治疗实施方面的真正差异，在将证据推广到不同环境时应加以考虑。
