A-307 Determining risk-based internal quality control frequency for biochemical testing using Sigma metrics and the QC Constellation tool

Abstract

Risk-based internal quality control (IQC) has been increasingly adopted in clinical laboratories to enhance analytical quality and patient safety. ISO 15189:2022 recommends designing IQC plans based on risk assessment rather than applying fixed QC frequencies. Sigma metrics combined with the QC Constellation tool provide an objective approach to optimize IQC strategies. A retrospective analysis of IQC and external quality assessment data was performed from October 2023 to September 2024 for six routine biochemical tests, including albumin, total bilirubin, cholesterol, triglyceride, gamma-glutamyl transferase, and lipase, analyzed on the AU5800 biochemical analyzer at the University Medical Center Ho Chi Minh City. Sigma metrics were calculated using total allowable error, bias, and imprecision. The QC Constellation tool was applied to determine the optimal run size corresponding to a MaxE(Nuf) risk level of less than 1. Cholesterol demonstrated a Sigma performance of approximately 3, whereas the remaining analytes achieved Sigma metrics greater than 5. Based on these performance levels, the QC Constellation tool proposed optimized run sizes that allowed adjustment of IQC frequency according to analytical risk. The optimized QC plan reduced unnecessary QC events while maintaining acceptable error detection capability. The combined application of Sigma metrics and the QC Constellation tool provides an effective method for determining risk-based IQC frequency in biochemical testing. This approach minimizes the risk of undetected analytical errors, reduces QC-related costs, and supports compliance with ISO 15189:2022 requirements.