Setting up an own laboratory performance-based internal quality control plan - a model for complete blood count

Abstract

Quality Control (QC) in Romania is regulated by the Order of the Minister of Health no. 1608/2022 that modifies the previous Order 1301/2007. The new version of the Order introduces a more scientific approach by requesting the laboratories to assess test performance and then elaborate an appropriate internal QC plan. The aim of this study was to demonstrate how to design a QC plan for complete blood count (CBC) in an Emergency Laboratory with continuous activity, in order to comply with the new Order 1608/2022. QC data obtained over a three-month period (April-June 2022) from the Sysmex XN-1000 instrument of the Emergency Laboratory of the County Emergency Clinical Hospital of Târgu Mureș were included. In order to establish an appropriate QC plan, two models were applied and the following parameters were calculated: the number of daily QC runs (N), the probability of false rejection (Pfr), the QC frequency (run size), and the required QC rules. White blood cells achieved high performance, while Hematocrit performance was poor. Different levels of performance were achieved for Platelets. We emphasize that, when all parameters are measured on the same instrument, QC frequency and Pfr should be adjusted in order to develop a QC plan that “fits” all the parameters of the CBC as a whole. In our Emergency Laboratory, the calculated QC plan for CBC is N=2, Pfr=0.03, multi-rule 1:3s/2:2s/R:4s, and a run size of 95 samples which is approximately the same as the number of CBCs performed during one 12-hour shift.

Keywords

• cytology
• quality control and evidence based laboratory medicine