The application of sigma metrics quality models in quality management of clinical biochemistry laboratory

Abstract

Objective To improve the quality of clinical biochemistry laboratory by quality indicators of pre-analytical, analytical, post-analytical phase and the whole process. Methods Analytical Phase: The Sigma values of items were calculated, applying the equation Sigma=(TEa%-Bias%)/CV%. Total allowable error (TEa) is from analyticalal specification defined in WS/T403-2012 of China, Bias% is from the evaluation results of National Center for Clinical Laboratory (NCCL) trueness verification PT series and CV% is from internal quality control data during the last 6 months in our lab. Normalized Sigma metrics plot was made to evaluate the analysis performance and the quality control strategies were designed accordingly. The quality goal indexes (QGI) were also calculated to propose improvement measures for items below 6 Sigma. Quality indicators of pre-, post-analytical and whole analytical phase, such as quality of specimen, critical value notification, critical value notification in time, TAT of hs-cTnT, TAT of emergency biochemical items, rewrite of laboratory reports and unacceptable performance in EQA-PT were measured in Sigma metrics too. The Sigma metrics changes before and after taking improvement measures were compared to conform the effectiveness. Results The average Sigma value of 17 biochemical tests was 5.29, of which 8 items (UA, K, ALP, CK, AMY, AST, TG, Na) achieved excellent to world class level (≥5 Sigma), 6 items (LDH, Cre, TC, ALT, Mg, Glu) achieved marginal to good level (5>Sigma≥3), BUN performed poorly (3>Sigma≥2), Ca, TP performed unacceptably (Sigma<2) with serious quality defects. The Sigma values of unacceptable specimen, critical value notification, critical value notification in time, unacceptable turn around time (TAT) of hs-cTnT, unacceptable turn around time (TAT) of emergency biochemical items, rewrite of laboratory reports, unacceptable performance in EQA-PT were 4.17, 3.60, 2.75, 1.72, 3.27, 4.52, 3.33 respectively, rising to 4.30, 4.30, 2.90, 2.45, 3.75, 4.80, 3.60 accordingly after improvement. Conclusions Sigma metrics is potentially an ideal approach for clinical biochemistry laboratories management, which is helpful to find out problems, put forward improvement measures, and confirm the effectiveness, so as to achieve the purpose of continuous quality improvement.(Chin J Lab Med, 2017, 40: 727-732) Key words: Clinical chemistry tests; Quality control; Laboratories, hospital; Quality indicators, health care; Quality improvement