Evaluation of Homemade Lyophilized Serum as External Quality Control Material for Clinical Chemistry Tests based on Variance Index Score

Abstract

Background: External Quality Assurance (EQAS) is crucial for maintaining accuracy in clinical laboratory results. However, the high cost of commercial serum controls often limits participation, particularly in developing countries. This study aims to compare the performance of homemade lyophilized serum with commercial control serum as a cost-effective alternative for EQAS, using the Variance Index Score (VIS) for evaluation. Methods: A comparative observational study was conducted in 15 general medical laboratories from January to September 2024. Homemade lyophilized serum was prepared from pooled serum of healthy volunteers. Both homemade and commercial serum were tested for eight clinical chemistry parameters: glucose, uric acid, cholesterol, triglyceride, SGOT, SGPT, urea, and creatinine. VIS was calculated based on the difference between laboratory results and target values, and statistical analysis compared the two types of serum. Results: Commercial control serum produced results with higher mean values and lower variation compared to homemade serum. Despite higher variability in the homemade serum, no significant difference in VIS was found between the two groups (p > 0.05) for all tested parameters. Conclusion: Homemade lyophilized serum, though more variable, demonstrated comparable performance to commercial controls, making it a viable cost-effective alternative for EQAS. Further studies are recommended to assess long-term stability and quality.