Cost-effective laboratory testing.

The increased utilization of diagnostic procedures has prompted interest in cost-effective laboratory testing. Clinically useful tests-useful in the sense that the patient benefits-are cost effective. The choice of test(s) is determined by the risks and benefits of proposed management. In practice, the first step in cost-effective laboratory testing is to define the clinical problem; the next step is to choose the test(s) that minimize the risks of making a false diagnosis. The choice will depend on whether sensitivity, specificity, or both are needed to decrease diagnostic uncertainty to the extent that management does more good than harm.