The principles of evidence-based medicine provide the tools to incorporate the best evidence into everyday practice. Evidence-based medicine is the integration of individual clinical expertise with the best available research evidence from systematic research and the patient's values
and expectations. A hierarchy of evidence can be used to assess the strength of evidence upon which clinical decisions are made, with randomized studies at the top of the hierarchy. The efficient approach to finding the best evidence is to identify a systematic review or evidence-based clinical
practice guidelines. Calculated metrics, such as sensitivity, specificity, receiver-operating-characteristic curves, and likelihood ratios, can be used to examine the evidence for a diagnostic test. High-level studies of a therapy are prospective, randomized, blinded, placebo-controlled, have
a concealed allocation, have a parallel design, and assess patient-important outcomes. Metrics used to assess the evidence for a therapy include event rate, relative risk, relative risk reduction, absolute risk reduction, number needed to treat, and odds ratio. Although not all tenets of evidence-based
medicine are universally accepted, the principles of evidence-based medicine nonetheless provide a valuable approach to respiratory care practice.