Risk-based redesign of internal quality control procedures for emergency immunoassays in clinical laboratories: a multicenter study from China
Background Although clinical laboratories routinely implement internal quality control (IQC) to ensure the reliability of test results, emergency immunoassay testing introduces unique operational challenges. To mitigate financial burdens, some laboratories arbitrarily extend IQC batch lengths or reduce the number of quality control (QC) samples per analytical run. This study evaluated baseline IQC practices for emergency immunoassays across five laboratories in Suining, China, aiming to provide evidence-based guidance for regional quality improvement. Methods Average daily test volumes, external quality assessment (EQA) results, and historical IQC data were retrospectively collected from the five laboratories. Sigma metrics were calculated for each analyte. Concurrently, the “Westgard Sigma Rule with Run Length” nomogram was applied to design individualized, risk-based statistical quality control (RB-SQC) procedures. Results All emergency immunoassays, except for serum procalcitonin, were subjected to routine IQC across all five laboratories; notably, certain analytes followed an extended 72-h IQC batch interval. Within individual laboratories, QC rules, the number of QC results per batch, and batch lengths were consistent across analytes but varied between laboratories. Under the current QC scheme, the QC utilization rate (N/M-1) was 0.087 (0.047–0.143), which decreased significantly to 0.020 (0.004–0.133) after implementing RB-SQC procedures (N/M-2; Z = 3.154, P < 0.05), suggesting that RB-SQC may reduce QC material and reagent consumption while maintaining acceptable patient risk. However, arbitrary adjustments to batch lengths or the number of QC results may lead to elevated or reduced QC utilization rates. Conclusions Baseline IQC practices for emergency immunoassays in the surveyed laboratories were inconsistent and lacked a standardized risk-based foundation. We recommend that clinical laboratories implement individualized RB-SQC protocols designed using the Westgard Sigma Rule with Run Length nomogram, and periodically reassess their appropriateness based on updated sigma metrics.