Applying external trial evidence to the patient sitting in front of you in the clinical setting is perhaps one of the most difficult and least discussed steps of evidence-based medicine.^1,2 Having unearthed relevant, high-quality, and valid information from clinical trials in relation to a clinical question generated by a patient encounter, you must answer 5 questions to successfully apply such information to your individual patient.³

Participants in clinical trials may differ in obvious ways such as age, sex, and clinical disease type from the patient in your office (Table 1).⁴ In most circumstances, these differences do not prevent you from making some useful generalizations from the literature. For example, I would be quite happy to generalize from a randomized clinical trial (RCT) of topical steroids for atopic eczema that did not use strict diagnostic criteria, provided that the description of the disease made sense to me, for example, "itchy red flexural eczema."