Evaluation of the clinical accuracy of laboratory tests.

Fundamental clinical performance of a laboratory test can be described in terms of accuracy, or the ability to correctly classify subjects into clinically relevant subgroups. Accuracy refers to the quality of the information provided by the classification device and should be distinguished from the efficacy, or practical usefulness, of the information. Receiver operating characteristic curves provide a pure index of accuracy by demonstrating the limits of a test's ability to discriminate between alternative states of health over the complete spectrum of operating conditions. If analytical imprecision is removed from the data, the resulting receiver operating characteristic curve represents the inherent biological variation that ultimately limits the clinical accuracy of the test.