Evidence-based medicine in action: Critical appraisal of articles on therapy or intervention

Abstract

Evidence-based medicine (EBM) has gained acceptance as a means to improve patient outcomes. However, the practice of EBM necessitates the acquisition of certain skills beginning with the formulation of an answerable clinical question, effective search of the literature to find the best evidence, critically evaluating the evidence for its validity and the application of good evidence to patients giving due respect to their preferences and the clinician's individual expertise. Systematically analyzing the evidence is crucial to identifying the presence and degree of bias in the study, to determine the magnitude of the results in clinically relevant terms and deciding on the applicability to a particular patient. This process is termed critical appraisal. As research questions decide the appropriate study designs, the tools used for critically appraising different types of articles also vary. In general, critical appraisal of articles on therapy or intervention seek to clarify three issues – the internal validity of the study, the magnitude and precision of results, and the external validity of the study. This review aims to elucidate the practical ways in which each of these components of a critical appraisal can be approached and finally enable the clinician to use or ignore the evidence at hand. Since the acquisition of skills such as critical appraisal needs repetitive exposures and continuous constructive feedback, journal clubs offer ideal occasions where they can be initiated, pursued, and mastered. Judicious application of critical appraisal would no doubt aid the effective practice of EBM and ultimately improve patient care.