B-118 Nine-Year Evaluation of Hepatitis Viral Marker Testing Through the Korean Association of External Quality Assessment Service (KEQAS) Program

Abstract Background The Korean Association of External Quality Assessment Service (KEQAS) has conducted an external quality assessment (EQA) program for hepatitis viral markers from 2016 to 2024. This study aimed to evaluate the proficiency of participating laboratories in detecting hepatitis A, B, and C viral markers using pooled serum specimens and to identify areas for improvement in diagnostic testing quality. Methods The EQA program was conducted biannually, assessing 10 test items: hepatitis B surface antigen (HBsAg), antibodies to HBsAg (anti-HBs), hepatitis B core antibodies (anti-HBc total and IgM), hepatitis B envelope antigen (HBeAg), antibodies to HBeAg (anti-HBe), anti-hepatitis C virus (anti-HCV), and anti-hepatitis A virus (anti-HAV total, IgG, and IgM). Pooled sera specimens were prepared using fresh frozen plasma and distributed to participating laboratories. Results were collected via an online platform and analyzed based on testing methods, instruments used, and proficiency rates. Results Over the nine-year period, participation increased from 915 laboratories in 2016 to 1,166 in 2024, with response rates consistently exceeding 95%. Chemiluminescence immunoassay (CLIA) and electrochemiluminescence immunoassay (ECLIA) were the most frequently used methods, demonstrating high sensitivity and specificity. Immunochromatographic assays (ICA) exhibited lower sensitivity, leading to false-negative results, particularly for HBeAg and anti-HCV. The proficiency rates for HBsAg and anti-HBs tests exceeded 99%, while anti-HBc total and anti-HBc IgM tests showed agreement rates above 98%. HBeAg tests exhibited slightly lower concordance due to matrix effects in pooled sera. Anti-HAV total and IgG tests maintained concordance rates above 95%, though ICA usage occasionally led to false-negative results. These findings underscore the need for continuous evaluation and improvement in diagnostic testing methodologies. Conclusion The nine-year KEQAS EQA program demonstrated significant improvements in the quality of hepatitis viral marker testing in Korea. High participation rates and robust statistical analyses highlighted the reliability of automated immunoassay methods while identifying the limitations of ICA. Continued participation in EQA programs is essential for maintaining high diagnostic standards. Future efforts should focus on improving ICA sensitivity and minimizing matrix effects in pooled sera preparation.