The evaluation of diagnostic tests: evidence on technical and diagnostic accuracy, impact on patient outcome and cost-effectiveness is needed.

OBJECTIVE: Before introducing a test in clinical practice, its characteristics and added value should be assessed. Diagnostic accuracy studies only are not sufficient; the test's impact on patient outcome ought to be assessed as well. To do this, we propose a stepwise evaluation of diagnostic tests. STUDY DESIGN AND SETTING: Theoretical-conceptual approach. RESULTS: First, the test's technical accuracy refers to the ability to produce usable information under standardized conditions. In a second step, the place of the new test in the clinical pathway is determined. Thirdly, the test's diagnostic accuracy is assessed, depending on its intended goal. The fourth step assesses the test's impact on the patient outcome. Depending on the place of the test in the clinical pathway, existing evidence can be used, or new evidence will be needed. At the final step, a cost-effectiveness analysis assesses the test's financial and societal consequences. CONCLUSION: Diagnostic tests evaluation should consider the technical accuracy, the test's place in the clinical pathway, its diagnostic accuracy, and its impact on patient outcome