Evidence-based medicine, part 4. An introduction to critical appraisal of articles on harm

This article provides an introductory step-by-step process to appraise an article on harm. The authors introduce these principles using a systematic approach and case-based format. The process of assessing the validity of an article on harm, determining its importance, and applying it to an individual patient is reviewed. The concepts of study population homogeneity, equal treatment, sufficient follow-up periods, and completeness are discussed to help physicians determine an article's validity. Instruction on calculating odds ratios, relative risk, absolute risk increase, and the number needed to harm is provided and applied to the clinical scenario. Finally, information that is learned from the previous two steps is applied to patient care. Study generalizability and the role of patient values, patient expectations, and patient concerns are also addressed. The skills learned from appraising an article on harm in the manner outlined provides a solid basis for lifelong learning and improved patient care.