Comparative performance of the Siemens Atellica and Abbott Architect assays for HBsAg quantification in patients with chronic hepatitis B or hepatitis Delta

Quantitative hepatitis B surface antigen (qHBsAg) is a routine marker for monitoring patients with chronic hepatitis B (CHB) or Delta (CHD). New commercially available assays require independent evaluation in clinical laboratories before being adopted for routine use. This study assessed the performance of the new Siemens Atellica IM Quantitative HBsAg (QHBs) assay in patients with CHB or CHD. Over a six-month period, all serum specimens from patients with CHB or CHD that were submitted to the laboratory for qHBsAg testing were prospectively analyzed using both the historically used Architect assay and the new Atellica assay. Furthermore, in a retrospective longitudinal analysis, we examined CHD patients who showed a reduction of at least 1 log 10 UI/mL in HBsAg levels over the course of treatment. A total of 311 serum samples from 216 patients were prospectively evaluated. The Architect assay yielded slightly higher values than the Atellica assay (mean difference: +0.10 log₁₀ IU/mL). There was excellent agreement and correlation between the two assays (Spearman’s Rs = 0.99; 95 % CI [0.9877–0.9922]). Three samples with low HBsAg concentrations (0.02–0.07 IU/mL) were detected by the Atellica assay but not by the Architect assay. In the longitudinal follow-up of five CHD patients (82 samples), both assays produced comparable results and could be used interchangeably without any potential clinical impact. The Atellica assay demonstrated equivalent performance to the Architect assay for qHBsAg monitoring in patients with CHB or CHD. • HBsAg quantification is a key marker for monitoring chronic hepatitis B (CHB) or chronic hepatitis Delta (CHD). • The Atellica and Architect assays show strong correlation in HBsAg quantification among patients with CHB or CHD. • In CHD-treated patients, qHBsAg clearance rates were comparable between the Atellica and Architect assays.