Zhang Xin, Wu Yuxia, Ren Pengwei, Liu Xueting, Kang Deying
Department of Integrated Traditional Chinese and Western Medicine, West China Hospital, Sichuan University, Chengdu 610041, China.
Department of Evidence-based Medicine and Clinical Epidemiology, West China Hospital, Sichuan University, Chengdu 610041, China.
Contemp Clin Trials Commun. 2015 Nov 19;1:32-38. doi: 10.1016/j.conctc.2015.10.004. eCollection 2015 Oct 30.
To explore the relationship between the external validity and the internal validity of hypertension RCTs conducted in China.
Comprehensive literature searches were performed in Medline, Embase, Cochrane Central Register of Controlled Trials (CCTR), CBMdisc (Chinese biomedical literature database), CNKI (China National Knowledge Infrastructure/China Academic Journals Full-text Database) and VIP (Chinese scientific journals database) as well as advanced search strategies were used to locate hypertension RCTs. The risk of bias in RCTs was assessed by a modified scale, Jadad scale respectively, and then studies with 3 or more grading scores were included for the purpose of evaluating of external validity. A data extract form including 4 domains and 25 items was used to explore relationship of the external validity and the internal validity. Statistic analyses were performed by using SPSS software, version 21.0 (SPSS, Chicago, IL).
226 hypertension RCTs were included for final analysis. RCTs conducted in university affiliated hospitals (P < 0.001) or secondary/tertiary hospitals (P < 0.001) were scored at higher internal validity. Multi-center studies (median = 4.0, IQR = 2.0) were scored higher internal validity score than single-center studies (median = 3.0, IQR = 1.0) (P < 0.001). Funding-supported trials had better methodological quality (P < 0.001). In addition, the reporting of inclusion criteria also leads to better internal validity (P = 0.004). Multivariate regression indicated sample size, industry-funding, quality of life (QOL) taken as measure and the university affiliated hospital as trial setting had statistical significance (P < 0.001, P < 0.001, P = 0.001, P = 0.006 respectively).
Several components relate to the external validity of RCTs do associate with the internal validity, that do not stand in an easy relationship to each other. Regarding the poor reporting, other possible links between two variables need to trace in the future methodological researches.
探讨中国开展的高血压随机对照试验（RCT）的外部效度与内部效度之间的关系。
在Medline、Embase、Cochrane对照试验中心注册库（CCTR）、中国生物医学文献数据库（CBMdisc）、中国知网（CNKI/中国学术期刊全文数据库）和维普中文科技期刊数据库中进行全面的文献检索，并采用高级检索策略查找高血压RCT。分别采用改良量表、Jadad量表评估RCT中的偏倚风险，然后纳入评分在3分及以上的研究以评估外部效度。使用包含4个领域和25个条目的数据提取表来探讨外部效度与内部效度的关系。采用SPSS 21.0软件（SPSS，芝加哥，伊利诺伊州）进行统计分析。
共纳入226项高血压RCT进行最终分析。在大学附属医院（P < 0.001）或二级/三级医院开展的RCT内部效度得分较高（P < 0.001）。多中心研究（中位数 = 4.0，四分位间距 = 2.0）的内部效度得分高于单中心研究（中位数 = 3.0，四分位间距 = 1.0）（P < 0.001）。有资金支持的试验方法学质量更好（P < 0.001）。此外，纳入标准的报告也会带来更好的内部效度（P = 0.004）。多因素回归分析表明，样本量、行业资助、作为测量指标的生活质量（QOL）以及以大学附属医院作为试验场所具有统计学意义（分别为P < 0.001、P < 0.001、P = 0.001、P = 0.006）。
与RCT外部效度相关的几个因素确实与内部效度相关联，但它们之间的关系并不简单。鉴于报告质量较差，未来的方法学研究需要探寻两个变量之间其他可能的联系。
