ANALYTIC GOALS, CONCENTRATION RELATIONSHIPS, AND THE STATE-OF-THE-ARTFOR CLINICAL LABORATORY PRECISION

We analyzed the College of American Pathologists' Quality Assurance Se rvice 1990 database of 1500 clinical laboratories to evaluate concentr ation relationships and the state of the art for the precision of 37 a nalytes. We compared these data to previously reported Quality Assuran ce Service precision performance data from 1974 through 1980. The gene ral trend of decreasing average long-term, within-method, within-labor atory coefficients of variation continues. However, among 24 routine c hemical and therapeutic drug monitoring tests observed for 11 to 16 ye ars, 11 showed no evidence of continuous improvement in precision. The 1990 average coefficients of variation usually exceeded analytic goal s modeled by clinical responses when these models assumed that variabi lity in test results arises solely from the analytic performance of th e method. In contrast, they usually did not meet goals that take into account the presence of biologic factors among the sources of test var iation. Notable exceptions are the average coefficients of variation f or cholesterol and triglycerides, which markedly decreased during the National Cholesterol Education Program initiatives of the 1980s. Conti nuous improvement of precision in disciplines dominated by relatively mature automated methods may not be the norm unless structure and dire ction are provided by appropriate and accepted analytic goals.