Need for Confirmatory Neutralization Tests for Hepatitis B Surface Antigen Tests in Populations with Intermediate Prevalence

Efficient implementation of hepatitis B surface antigen confirmatory neutralization tests

INTRODUCTION

To prevent misreporting of false positives in the hepatitis B surface antigen (HBsAg) assay, it is recommended to confirm the low-positive cases with neutralization tests. However, currently not many facilities are implementing this due to the additional cost. The aim of this study was to clarify the risk factors for false positives in the high-sensitivity HBsAg quantitative tests to reduce the neutralization tests.

METHODS

In this retrospective cohort study, we analyzed 47,305 patients who had their HBsAg value measured at Sapporo Medical University Hospital between November 2016 and March 2022. The patients eligible for the neutralization tests were those with HBsAg values between 0.005 and 1.000, even after reexamination by high-speed centrifugation.

RESULTS

HBsAg quantitative tests were performed in 71,475 tests. Of these, 817 tests and 376 patients were subjected to neutralization tests. Of the patients who met the criteria, 329 were included in this study. Fifty-seven cases (17%) had negative results in the neutralization tests, suggesting false positives for the HBsAg assay. Multivariate analysis showed that younger age (adjusted odds ratio [aOR] 6.57), female sex (aOR 2.32), lower HBsAg values (aOR 59.6), and reagent improvement (aOR 2.06) were independent risk factors for false positives. The false-positive rate was actually high at 33.1% in the HBsAg range of 0.005-0.049 IU/mL and at 1.2% in the range above 0.050 IU/mL.

CONCLUSIONS

Confirmatory neutralization tests should be performed at least in the range of 0.005-0.049 IU/mL where quantification is possible with a higher-sensitivity assay.

Versatile performance edges of HBsAg Next assay in diagnosis and therapeutic monitoring of HBV infection

BACKGROUND

HBsAg Next assay (HBsAgNx) claims improved detection of HBsAg. The aim was to investigate its performance in ascertaining HBsAg loss, ability to detect HBsAg in various phases of HBV infection, specificity and its amenability to in-house neutralization.

METHODS

Analytical sensitivity was investigated using NIBSC standard (3rd WHO-IS). For clinical performance, out of 91,962 samples tested for HBsAg (Qual-II), 512 samples consisting of 170 cases with evidence of HBsAg loss during treatment (n = 116) and without treatment (n = 54), acute-hepatitis B (n = 90) and acute exacerbation of chronic-hepatitis B (n = 41), acute-hepatitis A (n = 24) and acute-hepatitis E (n = 9) positive, HIV-1 positive (n = 20), non-HBV, HAV and HEV related acute-hepatitis (n = 81) and HBsAg prozone (n = 14) as well as in-house neutralization (n = 63) were included.

RESULTS

The calculated limit of detection (LOD) was 0.004 IU/mL. Of the 170 patients with apparent HBsAg loss, 18/116 (15.5%) among treated and 15/54 (27.7%) with spontaneous clearance were positive in HBsAgNx (p < 0.0001). Additionally, it detected HBsAg in 12/95 (12.6%) and 6/34 (17.6%) patients who were HBV DNA negative in treatment experienced and spontaneous clearance groups respectively (p < 0.001). The specificity of HBsAgNx was comparable to HBsAg Qual-II. The signal-intensity of HBsAgNx was significantly higher than HBsAg Qual-II across various phases of HBV infection and prozone samples.

CONCLUSION

HBsAgNx significantly enhanced the accuracy of HBsAg detection without compromising the specificity in ascertaining HBsAg loss. The performance was superior in various phases of HBV infection including samples that exhibited prozone effect. Furthermore, it is amenable to cost-effective in-house neutralization to confirm low HBsAg levels.

Seroprevalence of Transfusion Transmissible Infections and Associated Risk Factors in Hospitalized Patients before Transfusion in Jinling Hospital Nanjing University: A Three-Year Retrospective Study

Transfusion-transmitted infections (TTIs), such as hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and treponema pallidum (TP), must be detected before blood transfusion. However, few studies have been conducted on the prevalence and accuracy of positive results in hospitalized patients. The purpose of this study was to investigate the real seroprevalence of TTIs among patients before blood transfusion and analyze the characteristics of false-positive results in Jinling Hospital, Nanjing University, China. TTI results were collected from medical records and analyzed retrospectively. Additionally, we also used confirmatory assays to verify the accuracy of positive results. The overall prevalence of TTI was 8.96%, which was related to gender and age. The real positive rates were 86.67% (HBV), 35.09% (HCV), 20.75% (HIV), and 100% (TP). Our results also showed that high-speed centrifugation can reduce the false-positive rate of HBsAg. In summary, the results demonstrated that the positive rates of TTIs in hospitalized patients are higher than those in the general population. We also confirmed the existence of false-positive results in serological screening for TTIs. The method of processing specimens through high-speed centrifugation could reduce the false-positive results of detecting antigens effectively.