Challenges in applying the results of clinical trials to clinical practice

The relevance of clinical trial results to clinical practice hinges on 2 critical questions: Will the results be replicated in one's practice, and Are the results clinically important? The answers to the following 5 questions may help one determine how relevant a study result is to clinical practice. First, have steps been taken to minimize bias (eg, masking, randomization)? Second, is the result likely due to the treatment (vs confounding factors)? Third, is the result unlikely to be due to chance? Fourth, is the study population representative of your patients? Fifth, is the totality of the evidence consistent across studies? To determine if a study result is likely to be clinically important, consider a 3-step approach. In step 1, decide, a priori, what a clinically meaningful difference between 2 treatments would be to define regions of beneficial, harmful, and trivial outcomes. In step 2, determine whether the CIs around the average outcome include the range of beneficial outcomes and lie outside the range of harmful outcomes. In step 3, determine the proportion of patients achieving a clinically meaningful benefit. If the CIs mostly include the range of beneficial outcomes and lie outside the range of clinically harmful outcomes and if a substantial proportion of patients achieve a clinically meaningful benefit, then the intervention is probably clinically important. Application of clinical trial results to clinical practice requires critical analysis of the extant literature as well as good clinical judgment.