How to generalize efficacy results of randomized trials: recommendations based on a systematic review of possible approaches Journal Articles uri icon

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abstract

  • AbstractRationale, aims and objectivesRandomized controlled trials (RCTs) are the preferred source for evidence for the effect of treatment. However, patients participating inRCTs often manifest important differences from patients seen in practice. Therefore, guideline developers have to decide whether the results are generalizable to the target population not represented inRCTs.MethodA systematic review of the literature was undertaken to identify methods to decide whether to generalize the results fromRCTs to patients who were not represented in these trials.ResultsOne approach is to examine the in‐ and exclusion criteria of trials and infer from these whether the trial population was sufficiently representative. Other authors suggest, because of the inclusion of a broader range of patients, reliance on observational studies if no direct evidence for the target population is available.Another approach is to apply the relative effect of treatment found in trials to patients in practice unless there is a compelling reason to believe the results would differ substantially as a function of particular characteristics of those patients. Although there are exceptions, this approach is supported by empirical evidence that, in general, relative effect of treatment on benefit outcomes seldom differs to an important extent across subgroups of patients.ConclusionWe propose this last approach: focusing onRCTs unless there is a compelling reason not to do so. Compelling reasons will most often be found with respect to issues of rare adverse effects, for which observational studies are likely to provide the best estimates.

publication date

  • August 2013