Publications

Background: Internal quality control (IQC) samples are used to monitor and evaluate the day to day analytical performance of parameters in a laboratory. While IQC is more useful in evaluating analytical precision, External quality assessment (EQA) can evaluate both precision and agreement with peers. With the introduction of newer software, IQC results can also be compared with peers to give an estimate of agreement in values. Aims: This study was undertaken to evaluate the agreement between the peer comparison scores obtained from EQA and IQC. The Z-score from EQA was compared with the Standard Deviation Index (SDI) from IQC peer comparison data using two common chemistry analytes, glucose and urea, on Siemen’s Dimension. Methodology: The monthly IQC Data from Unity Real Time (URT) software and the monthly EQA report of glucose and urea over a period one year was used for obtaining the two scores. The monthly Z score from EQA reports was compared with the corresponding monthly SDI calculated from IQC peer comparison data for the two parameters. Glucose and urea were analyzed on Siemen’s Dimension ExL fully automated Chemistry analyzer. Result: Our study showed similar trends in the performance of the parameters in the peer comparison scores between IQC and EQA. However, there was no statistically significant agreement between the two absolute scores. Conclusion: This study shows that although the peer comparison scores in performance of an analyte can be obtained from both IQC and EQA, it may not be appropriate to extrapolate the analyte performance observed in IQC to EQA in terms of absolute value in the scores. Keywords: Internal Quality Control (IQC), External Quality Assessment (EQA), Standard Deviation Index(SDI), Z score