Finding and evaluating the evidence: a critical step in evidence-based medicine.

Practitioners of evidence-based medicine are expected to review the evidence for treatment effectiveness with their patients as part of the shared decision-making process. This requires practitioners to know the evidence or to know how to find and evaluate it. To find the evidence, the practitioner must craft the search question by considering the domains of population, intervention, and outcome as a means to individualize the search for each patient. To evaluate the evidence, the practitioner needs to understand the strengths and weaknesses of various types of scientific evidence. Most practitioners will consult EBP guidelines first. If guidelines do not answer the search question, the practitioner will turn to systematic reviews, ensuring that their methods of selection and evaluation are explicit and appropriate. Searching the scientific literature for single studies is also possible, but evaluating primary sources is more difficult. Given the constraints of time and expertise, the authors anticipate that computerized expert systems, based on current evidence, will become increasingly prominent.