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Analyzing the Utility of Pooled Sera as Internal Quality Control for Immunoassay Parameters by an EWMA-backed
Prakruti Dash1, Saurav Nayak1, Tanushree Roy1
1Department of Biochemistry, All India Institute of Medical Sciences, Bhubaneswar, India.
Insights
Pooled sera offer a cost-effective internal quality control (IQC) for immunoassays. When combined with Exponentially Weighted Moving Average (EWMA) analysis, pooled sera demonstrate stable performance and enhance early error detection in clinical laboratories.
Area of Science:
- Clinical Biochemistry
- Laboratory Medicine
- Quality Control
Background:
- Internal Quality Control (IQC) is vital for reliable diagnostic testing in clinical labs.
- Commercial IQC materials are expensive and have limited availability.
- Pooled sera (PS) from patient samples present a cost-effective IQC alternative, but require validation.
Purpose of the Study:
- To assess pooled sera as IQC material for immunoassays using EWMA.
- To compare pooled sera IQC performance against commercial IQC materials.
Main Methods:
- Pooled sera were prepared and stored from discarded patient samples.
- Five immunoassay parameters were monitored for 60 days using pooled sera and commercial IQC.
- EWMA charts with a 7-day smoothing window were used for error detection analysis.
Main Results:
- Pooled sera IQC (ePSIQC) performance closely matched commercial IQC.
- EWMA analysis showed significant concordance for most parameters.
- ePSIQC demonstrated superior early error detection compared to traditional methods.
Conclusions:
- Pooled sera with EWMA offer a stable, cost-effective, and reliable IQC for immunoassays.
- EWMA enhances error detection, improving laboratory quality control.
- This approach is a viable solution for resource-limited settings.
Background:
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).
Objective:
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.
Method:
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.
Results:
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.
Conclusion:
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.
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