Impact of using cross-over CV and mean for two different lots of assay control on implementation of Westgard rules in chemical diagnostic tests.

BACKGROUND

The main challenges of clinical laboratories concerning quality control include cost-effectiveness, variability in standardized materials, and evolving technologies across various diagnostic fields. While traditional QC practices and automation systems provide for accuracy, gaps exist, especially when applying Westgard rules to control lots for multiple assays. Such gaps result in inconsistent QC outcomes and unaddressed challenges in diagnostic reliability.

OBJECTIVE

This study aims to assess the effect of the cross-over coefficient of variation (CV) and mean values for different assay control lots on implementing Westgard rules to improve QC practices and enhance the accuracy and reliability of diagnostic tests in molecular laboratories.

METHODS

Data from 18 Levy-Jennings charts, with two assay control lots, were analyzed. Statistical comparisons of failure rates before and after setting the actual SD were performed using chi-square or T-tests at p < 0.05.

RESULTS

The analysis of 18 Levy-Jennings charts showed a significant reduction in failure rates after establishing actual mean and SD values compared to cross-over CV. Of the charts, 11 exhibited differences in failure occurrences, particularly rejection failures, highlighting improved QC reliability.

CONCLUSION

These results emphasize the importance of accurate SD calculation in enhancing the effectiveness of Westgard rules. Therefore, establishing mean and SD values enhances QC reliability, reduces false failures, and ensures accurate Westgard rules application, while ongoing training in QC practices enhances diagnostic accuracy.