Running of Standards in Clinical Chemistry and the Use of the Control Chart

A novel quantitative evaluation method for quality control results

“…, based on the assessment number of Z-scores (1,2,3,4,5,6,7,8,9,10,12,14,16,18, and 20; Fig. 1 and Table 1) [5].…”

“…Two representative methods used to identify systematic errors in a clinical laboratory are the Levey-Jennings chart [1,2] and the Westgard multirule chart [3]. These 2 quality control (QC) procedures are 1 fundamentally limited, in that the test results from the QC materials are interpreted with eight semi-quantitative sections, including the following: less than -3 standard deviations (SDs), -3 SD to -2 SD, -2 SD to -1 SD, -1 SD to mean, mean to +1 SD, +1 SD to +2 SD, +2 SD to +3 SD, and over +3 SDs [3].…”

Contributions of CCLM to advances in quality control

“…The original chart used by Levey and Jennings was a Shewhart chart on which was plotted the mean of duplicate measurements of a patient sample [ 8 ]. The use of duplicate measurements of quality control was subsequently modified a couple of years later to a single measurement of quality control material, and " single measurement " statistical quality control has become the industry standard [ 9 ].…”

Six Sigma as a Quality Management Tool: Evaluation of Performance in Laboratory Medicine

“…Although many things remain to be improved, statistical quality control procedures have significantly enhanced analytical performances since they were first introduced in clinical laboratories in the late 1950s. Method validation studies and application of quality control samples have considerably reduced the error rates of the analytical phase (Levey, 1950;Henry RJ, 1952). A simple technique that we can use in our laboratories is to translate the method validation results into sigma metrics (Westgard, 2006a;Westgard, 2006b).…”