BRS - Using the Results

BRS - How Do I Use the Results?

To review, we use studies to examine the associations between exposures/interventions and outcomes in a relatively small SAMPLE of the larger population. We then attempt to GENERALIZE these results to the larger population. While the assessment of GENERALIZABILITY is often done after the study is completed, we should think about the intended uses of the study results prior to starting.

INTERNAL VALIDITY is important to make sure that the study results tell the truth about any associations in the sample.

EXTERNAL VALIDITY addresses the extent to which the sample resembles the larger population of patients to which we want to apply the results.

The concepts of internal validity are often fairly straightforward...A study is either randomized or not, blinded or not, etc.

The concepts of external validity are very dependent upon our understanding of the complexity of disease, our willingness to extrapolate data, and even our values. For instance, if a study of cholesterol medication is performed in a group of males 50-75, then are those study results applicable to women of the same age? Or older men? Reasonable physicians may disagree on these points.

To assess EXTERNAL VALIDITY or GENERALIZABILITY or APPLICABILITY (the terms are used interchangeably), review the inclusion and exclusion criteria for the study, and then look at the descriptions of the patients who are actually recruited and compare those with the population of patients for whom the results of this study are intended.