california clinical laboratory license verification

Some laboratory personnel mistake the requirement for calibration verification with that for evaluating linearity. Therefore, the curve of the instrument response, which can be parabolic or sigmoid-shaped, should not be confused with linearity between the measured value and the true value. The test results from this transformation should be linearly proportional to the true value of the analyte in the sample solutions ( Figure 1).

The responses may be transformed using a 4-parameter logistic formula or other formula such as logit-log. In some assays, the instrument response versus concentration of sample solutions is not linear for example, competitive radioimmunoassays have a parabolic-shaped instrument response when plotted against concentration and a sigmoid-shaped curve when the response is plotted against the logarithm of the concentration. 1 The points at the upper and lower limits of the analytic measurement range that acceptably fit a straight line determine the linear range. Handling linearity data in an objective manner will aid clinical laboratorians whose goal is to improve the quality of the tests they perform.Īccording to NCCLS EP6-A, a quantitative analytical method is said to be linear when the analyte recovery from a series of sample solutions (measured value) is linearly proportional to the actual concentration or content of the analyte (true value) in the sample solutions. Regression analysis, as developed as the polynomial method, is partly based on the experiences of the College of American Pathologists Instrumentation Resource Committee and has proved to be a robust statistical method.Ĭonclusions.-We provide general guidelines for handling non-linear results from a linearity evaluation. The lack-of-fit error and the 1986 NCCLS EP6-P G test are sensitive to imprecision and assume that the data are first order. Results.-Visual assessment, although simple, is subjective. We then evaluate the statistical methods for each procedure. Objective.-This article evaluates the concepts and importance of linearity evaluations for clinical tests.ĭesign.-We describe the theory and procedural steps of each linearity evaluation. Although an important part of quality control and method validation for clinical laboratories, linearity of clinical tests does not get the attention it deserves.

Context.-Clinical laboratory assessment of test linearity is often limited to satisfying regulatory requirements rather than integrating this tool into the laboratory quality assurance program.

California clinical laboratory license verification