Know the categories of medical evidence and the evidence-based medicine (EBM) approach.

Physicians are charged with the task of keeping up-to-date with the latest medical research and innovations. The practice of EBM enables clinicians to synthesize this ever-growing body of knowledge, as well as helps them to apply this information to individual patients. Physicians also need to be familiar with the classes of research reports and the conclusion grades for evidence.

EBM is practiced when clinicians integrate the best available evidence and their clinical expertise in making decisions about their patients’ care. There are five necessary steps in the practice of EBM.

First, the need for information must be converted into answerable questions. Research can only answer specific questions. For instance, “How effective are inhaled corticosteroids in the prevention of asthma symptoms?” is an answerable question, whereas “What is the best way to treat asthma?” is not. An appropriate question has four components: (a) a patient or a problem, (b) an intervention, (c) an intervention for comparison, if applicable, and (d) a clinical outcome.

Second, the best evidence must be found in the most efficient manner. The ACP Journal Club and Evidence-Based Medicine are two journals that screen, analytically appraise, and compile articles from other publications. The Cochrane Database is a growing collection of comprehensive reviews of clinical interventions based on meta-analyses of rigorously chosen articles. These sources of information give physicians quick access to the best evidence.

Third, the evidence must be critically appraised for its internal validity and generalizability. Internal validity examines whether the results for the patients in the study are true, and it is threatened by bias and chance. Bias is a systematic error that could falsify the results. Chance effects, which are depicted with P values, power, and confidence intervals, can be minimized by studying a large population. Generalizability requires the judgment of the
clinician and refers to whether the study results are applicable to a particular population of patients.