Randomized, controlled trials, observational studies, and the hierarchy of research designs.
Randomized, controlled trials, observational studies, and the hierarchy of research designs.
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DOI：
10.1056/nejm200006223422507
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发表时间：
2000-06-22
影响因子：
158.5
通讯作者：
Horwitz, RI
中科院分区：
文献类型：
--
作者：
Concato, J;Shah, N;Horwitz, RI
背景资料：在研究设计的层次结构中，随机对照试验的结果被认为是最高等级的证据，而观察性研究被认为有效性较低，因为据报道它们高估了治疗效果。我们使用已发表的荟萃分析来识别检查相同临床主题的随机临床试验和观察性研究。然后，我们比较了原始报告的结果，根据类型的research design.Methods：检索Medline数据库发表在五个主要的医学期刊，1991年至1995年确定的随机，对照试验和荟萃分析的队列或病例对照研究，评估相同的干预措施。对于每五个主题，汇总估计值和95%的置信区间计算的基础上，从个人的随机对照试验和个人observational studies.Results的数据：对于五个临床主题和99份报告进行了评价，观察性研究的平均结果是显着相似的随机对照试验。例如，对卡介苗预防活动性肺结核有效性的13个随机对照试验的分析得出相对危险度为0.49（95%置信区间，0.34至0.70），相比之下，（95%置信区间，0.39至0.65）从10个病例对照研究。此外，在随机对照试验中，疫苗接种效果的点估计值范围更广（0.20至1.56），而非观察性研究（0.17 ~ 0.84）。结论：精心设计的观察性研究的结果（采用队列或病例对照设计）与同一主题的随机对照试验相比，不要系统性地高估治疗效果的大小。（N Engl J Med 2000;342：1887-92.）（C）2000年，马萨诸塞州医学会。
Background: In the hierarchy of research designs, the results of randomized, controlled trials are considered to be evidence of the highest grade, whereas observational studies are viewed as having less validity because they reportedly overestimate treatment effects. We used published meta-analyses to identify randomized clinical trials and observational studies that examined the same clinical topics. We then compared the results of the original reports according to the type of research design.Methods: A search of the Medline data base for articles published in five major medical journals from 1991 to 1995 identified meta-analyses of randomized, controlled trials and meta-analyses of either cohort or case-control studies that assessed the same intervention. For each of five topics, summary estimates and 95 percent confidence intervals were calculated on the basis of data from the individual randomized, controlled trials and the individual observational studies.Results: For the five clinical topics and 99 reports evaluated, the average results of the observational studies were remarkably similar to those of the randomized, controlled trials. For example, analysis of 13 randomized, controlled trials of the effectiveness of bacille Calmette-Guerin vaccine in preventing active tuberculosis yielded a relative risk of 0.49 (95 percent confidence interval, 0.34 to 0.70) among vaccinated patients, as compared with an odds ratio of 0.50 (95 percent confidence interval, 0.39 to 0.65) from 10 case-control studies. In addition, the range of the point estimates for the effect of vaccination was wider for the randomized, controlled trials (0.20 to 1.56) than for the observational studies (0.17 to 0.84).Conclusions: The results of well-designed observational studies (with either a cohort or a case-control design) do not systematically overestimate the magnitude of the effects of treatment as compared with those in randomized, controlled trials on the same topic. (N Engl J Med 2000;342:1887-92.) (C)2000, Massachusetts Medical Society.