Examining diagnostic tests: an evidence-based perspective

Diagnosis is an important aspect of physical therapist practice. Selecting tests that will provide the most accurate information and evaluating the results appropriately are important clinical skills. Most of the discussion in physical therapy to date has centered on defining diagnosis, with considerably less attention paid to elucidating the diagnostic process. Determining the best diagnostic tests for use in clinical situations requires an ability to appraise evidence in the literature that describes the accuracy and interpretation of the results of testing. Important issues for judging studies of diagnostic tests are not widely disseminated or adhered to in the literature. Lack of awareness of these issues may lead to misinterpretation of the results. The application of evidence to clinical practice also requires an understanding of evidence and its use in decision making. The purpose of this article is to present an evidence-based perspective on the diagnostic process in physical therapy. Issues relevant to the appraisal of evidence regarding diagnostic tests and integration of the evidence into patient management are presented.