Department of Evidence-Based Medicine and Clinical Epidemiology, West China Hospital, Sichuan University, Chengdu, China.
PLoS One. 2013 Dec 6;8(12):e82324. doi: 10.1371/journal.pone.0082324. eCollection 2013.
To explore external validity of randomized controlled trials (RCTs) of hypertension within China from the view of sample representation.
Comprehensive literature searches were performed in Medline, Embase, Cochrane Central Register of Controlled Trials (CCTR) et al and advanced search strategies were used to locate hypertension RCTs as well as observational studies conducted in China during 1996 to 2009 synchronously. The risk of bias in RCTs and observational studies was assessed by two modified scales respectively, and then both types of studies with 3 or more grading scores were included for the purpose of evaluating of external validity. Following that the study characteristics relative to sample representation were extracted from RCTs and observational studies synchronously, and the later were taken as external references for validating sample representation of RCTs.
226 hypertension RCTs and 21 observational studies were included for final analysis. Comparing samples with observational studies, the mean age of samples within RCTs was 54.46 years, significantly lower than that of observational studies (66.35 years) (P=0.002). The average disease course in patients of RCTs was 3.89 years and grade III hypertensive patients accounted for 17%; both were lower than that of the observational studies (12.96 years, P<0.001; 34%, P=0.026 respectively). In addition, the proportions of patients with complications due to heart failure, stroke, diabetes, or coronary heart disease in RCTs were 8%, 5%, 12% and 11% correspondingly, all of which were significantly less than that of observational studies (11%, 18%, 17% and 29%).
Sample characteristics within hypertension RCTs were significantly different from those in observational studies. The samples in most RCTs were under-represented. It's feasible to take samples of observational studies as a mirror of the actual composition of hypertension patients in the real world, if the reporting of observational studies is abundant and available.
从样本代表性的角度探讨中国高血压随机对照试验（RCT）的外部有效性。
全面检索 Medline、Embase、Cochrane 中心对照试验注册库（CCTR）等数据库，并采用高级检索策略同步检索 1996 年至 2009 年期间在中国进行的高血压 RCT 和观察性研究。采用两种改良量表评估 RCT 和观察性研究的偏倚风险，然后纳入两种类型的研究，只要有 3 个或更多的评分等级即可进行外部有效性评估。随后，从 RCT 和观察性研究中同步提取与样本代表性相关的研究特征，并将后者作为验证 RCT 样本代表性的外部参考。
共纳入 226 项高血压 RCT 和 21 项观察性研究进行最终分析。与观察性研究的样本相比，RCT 样本的平均年龄为 54.46 岁，明显低于观察性研究（66.35 岁）（P=0.002）。RCT 患者的平均病程为 3.89 年，三级高血压患者占 17%；均低于观察性研究（12.96 年，P<0.001；34%，P=0.026）。此外，RCT 中心力衰竭、中风、糖尿病或冠心病并发症患者的比例分别为 8%、5%、12%和 11%，均明显低于观察性研究（11%、18%、17%和 29%）。
高血压 RCT 中的样本特征与观察性研究明显不同。大多数 RCT 中的样本代表性不足。如果观察性研究的报告丰富且可用，则可以将观察性研究的样本作为真实世界中高血压患者实际构成的镜子。
