Analyzing the Utility of Pooled Sera as Internal Quality Control for Immunoassay Parameters by an EWMA-backed...

Internal Quality Control (IQC) is a cornerstone of clinical laboratory operations, ensuring reliability in diagnostic testing. Commercial IQC materials, though effective, pose challenges of high cost, limited availability, and susceptibility to matrix effects. Pooled sera (PS), derived from discarded patient samples, offer a cost-effective alternative. However, the stability and performance of pooled sera as IQC material in immunoassays need robust evaluation, particularly when combined with advanced statistical tools like Exponentially Weighted Moving Average (EWMA).

To evaluate the utility of pooled sera as IQC material for immunoassay parameters using the EWMA statistical approach and compare its performance against commercially available IQC materials.

A study was conducted in the clinical biochemistry laboratory at AIIMS Bhubaneswar. Pooled sera were prepared from discarded patient samples, aliquoted, and stored at -5°C. Five immunoassay parameters (Free T3, Free T4, TSH, Cortisol, and Ferritin) were monitored over 60 days using both pooled sera and commercial IQC materials. EWMA charts with a 7-day smoothing window were employed to assess error detection. Performance metrics, including Mean Squared Error (MSE), Root Mean Squared Error (RMSE), and Concordance Correlation Coefficient (CCC), were analyzed. Statistical significance was set at p<0.05.

The EWMA analysis of pooled sera (ePSIQC) closely mirrored commercial IQC performance. Concordance was significant for all parameters except Free T4. The ePSIQC method demonstrated superior early error detection compared to traditional Westgard Multirules. Pooled sera remained stable throughout the study duration, with deviations observed only in a few instances.

Pooled sera, combined with EWMA, provides a cost-effective, stable, and reliable alternative to commercial IQC materials for immunoassays. The enhanced error detection capability of EWMA strengthens laboratory quality control, offering a viable solution for resource-limited settings.