Biological interpretation of relative risk.
There is widespread interest in assessing the clinical importance of a study result. This goal is impeded, however, by a lack of clarity about the biological interpretability of epidemiological effect measures, such as the relative risk. A relative risk is often interpreted merely as a measure of some vague statistical association, without a view toward a biological effect as an object of measurement. Not infrequently, if it is not statistically significant, the relative risk estimate is ignored completely. A key to biological interpretation is appreciating the theoretical framework stipulating that outcome rates derived from 2 comparison groups actually represent measures of different effects in the same population. For instance, by using a placebo group to estimate the number of background cases that occurred in the treatment group, an estimate of the number of excess cases that occurred as a result of treatment can be made. This kind of biological entity can be derived from a relative risk, and can be more easily evaluated as to its clinical importance than a statistical association or a statement about statistical significance. Interpretation then becomes a more directed task, with a focus on the validity of certain ancillary hypotheses upon which biological interpretability rests.
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Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut 06877-0368, USA. slanes@rdg.boehringer-ingelheim.com
D015984:Causality; D017326:Clinical Trials, Phase III as Topic; D004341:Drug Evaluation / Q000379:methods* / Q000706:statistics & numerical data; D064420:Drug-Related Side Effects and Adverse Reactions; D015981:Epidemiologic Factors; D006801:Humans; D012306:Risk