Retest improvement for minipool nucleic acid testing positive samples

Abstract

Objective To analyze the correlation between the distribution interval of minipool nucleic acid testing(NAT) positive CT value and the resolution rate, so as to improve the retest model and reduce residual risk of blood transfusion. Methods The resolution testing results by Cobas S201 system of our blood center from January 2017 to December 2021 were retrospective analyzed, and the retest model was developed based on the distribution interval of CT values. For minipool NAT HBV positive samples from March 2022 to March 2023, synchronous detection was conducted by Cobas S201 and Panther detection system, and the detection results were statistically analyzed. Results From 2017 to 2021, 474 were minipool NAT positive, among which 324 were HBV positive, accounting for 68.35%. From 2017 to 2020, the proportion of HBV positive per year was significantly higher than that of HCV and HIV(P40, with the resolution rate at 95.8%, 56.5% and 14.8% respectively(P40, 36<CT value≤40 intervals respectively, with the concordance rate at 100%, 100%, and 81.25% by Cobas S201 and Panther detcetion. Nine samples presented inconsistent results: 4 samples were resolution negative by Cobas S201 but positve by Panther, 3 were repeatable positive and 1 was non-repeatable positive by Cobas S201. These 9 samples were seen as unqualified, but according to original rules(non-repeatable positive samples were seen as qualified), missed detection of at least 3 samples might occur. Conclusion There was a certain proportion of non-repeatable positive samples in positive pool, and the rules (non-repeatable positive samples were seen as qualified) have a risk of missed detection. Those with 36<CT value ≤40 interval should be rested to ensure blood safety and save restest cost.

Keywords

• hepatitis b virus(hbv)
• nucleic acid testing(nat)
• minipool testing
• residual risk