Background

In August 2022, we changed HBsAg testing for blood screening from the Alinity i HBsAg Qualitative II assay to a newer version, the Alinity i HBsAg Next assay on the Alinity i fully automated system. According to the manufacturer, the new assay is offering a higher analytical sensitivity. While a higher sensitivity is desired, the specificity of a screening assay is critical as well, since false reactive results will lead to an unnecessary rejection of donations and an increased workload.

Methods

The analysis timeframe covered all year 2022, samples were tested with the Alinity i HBsAg Qualitative II assay (Abbott GmbH, Germany) from January 1, 2022 until August, 2022, replaced by the Alinity i HBsAg Next assay (Abbott GmbH) until the end of the year. In addition to the initial and repeat reactive rate of both assays, we also analyzed the distribution of sample to cut-off (S/CO) values of the negative results as a measure to determine the discrimination power of the assays.

Results

Over 200.000 samples were tested in 2022, with more than 100.000 using the Alinity i HBsAg Qual II assay and more than 90.000 samples using the Alinity i HBsAg Next assay. We observed a reduction in the overall initial reactive rate for the Alinity HBsAg Next compared to its predecessor in the investigated time frame. Especially in the low positive range of the assay (1-10 S/CO), we detected a reduction in initial reactive rates. However, we did not observe a change in the rate of high-positive samples (>1000 S/CO).

Conclusion

Overall, the data demonstrated that the new Alinity HBsAg Next assay has a better specificity and sensitivity compared to the comparator assay Alinity i HBsAg Qual II in our blood screening setting. Despite the reported higher sensitivity, the new assay design has lowered the initial reactive rate. This reduced the number of repeated testing substantially and is leading to an improved workflow and a reduction of repeat testing in our setting.

Offenlegung Interessenkonflikt:

None.