The likelihood quotient line, a tool for the assessment of diagnostic validity of clinical chemical tests.

A detailed study of decision criteria for detection of Edema Proteinuria Hypertension (EPH) gestosis on the basis of uric acid concentration in serum has been recently described by Haeckel et al. (1981) J. Clin. Chem. clin. Biochem. 19, 173-176). These authors compared Receiver Operating Characteristic (ROC) Curve analysis, the determination of maximum efficiency, and the maximal information content. We recently developed a method of resolving this type of decision problem using the so-called Likelihood Quotient line (LQ line) which is also useful for assessing the validity of quantitative tests with respect to particular clinical decision problems (Keller, H & Gessner, U. (1981) Med. Lab. 34, 3-7; 31-39; Z. Med. Lab. Diagn. 22, 179-188). In this communication we demonstrate our approach using the same example as Haeckel et al., compare the results, and discuss further advantages of the LQ line.