ISSN:0277-6715    

DOI:10.1002/sim.4780060302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780060303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractWhen asking ‘what is known’ about a drug or therapy or program at any time, both researchers and practitioners often confront more than a single study. Facing a variety of findings, where conflicts may outweigh agreement, how can a reviewer constructively approach the task? In this discussion, I will outline some questions that canonlybe answered by examining agroupof independent studies. I will also discuss some pitfalls that sometimes swamp the benefits we can gain from synthesis. Most of these pitfalls are avoidable if anticipated early in a review. Thebenefitsof a quantitative review include information about how to match a treatment with the most promising recipients; increasing the statistical power to detect a significant new treatment; telling us when ‘contextual effects’ are important; helping us to assess the stability and robustness of treatment effectivenes; and informing us when research finds are especially sensitive to investigators' research design. Thepitfallsinclude aggregating data from studies on different populations; aggregating when there is more than one underlying measure of central tendency; and emphasizing an average outcome when partitioning variance gives far more useful info

ISSN:0277-6715    

DOI:10.1002/sim.4780060304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780060305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780060306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780060307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractIn order to avoid selective biases and to minimize random errors, inference about the effects of treatment on serious endpoints needs to be based not on one, or a few, of the available trial results, but on a systematic overview of the totality of the evidence from all the relevant unconfounded randomized trials. But, only where coverage of all, or nearly all, randomized patients in all relevant trials (or a reasonably unbiased sample of such trials) can be assured, is a systematic overview of trials reasonably trustworthy, for then any selective biases are likely to be small in comparison with any moderate effects of treatment. Checks for the existence of such biases can best be conducted if reasonably detailed data are available from each trial. Future trials should take into account the results of any relevant overviews in their design, and should plan to obtain sufficient numbers of events to contribute substantially to such overviews. In many cases, this implies the need for randomized trials that are much larger than is currently standard.

ISSN:0277-6715    

DOI:10.1002/sim.4780060308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780060309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractData from six randomized, placebo‐controlled clinical trials of aspirin, involving a total of 10,703 post‐myocardial infarction patients, have been compared and combined. An apparent heterogeneity of findings among the six trials with respect to all‐cause mortality is noted (P = 0.08). The reasons for this heterogeneity are explored. Two common methods of combining the results of several trials – the logrank and the log odds ratio methods – yield two‐sidedP‐values of 0.112 and 0.110, respectively, for the aspirin‐placebo effect on all‐cause mortality. Alternative statistical methods of combining the results of the six trials give two‐sidedP‐values rangin

ISSN:0277-6715    

DOI:10.1002/sim.4780060310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780060311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY