Quantification of hepatitis B e antigen between Elecsys HBeAg and Architect HBeAg assays among patients infected with...

Among patients infected with hepatitis B virus (HBV), quantification of hepatitis B e antigen (HBeAg) is accruing substantial clinical relevance as a marker for HBeAg-loss during treatment. No direct comparison has been made between assays that quantify HBeAg.

To compare the performance of HBeAg quantification (qHBeAg) between Architect and Elecsys HBeAg assays among 183 patients with chronic HBV infection (94 treatment-naïve HBV-monoinfected and 89 antiretroviral-experienced HIV-HBV co-infected).

qHBeAg was determined in Paul Erlich Institute Units (PEIU)/mL using previously designed protocols. Values were compared with correlation and linear regression. Bland-Altman analysis was used to compare mean differences (d¯) between Elecsys and Architect assays and limits of agreement (LOA) (±2 standard deviations [SD]).

Between-assay correlation was significant overall (r = 0.970), yet stronger for qHBeAg < 1000 (n = 131) versus > 1000PEIU/mL (n = 52) as determined by the Elecsys assay (r = 0.969 vs. 0.880, respectively). On average, the Elecsys assay reported qHBeAg at 13.3PEIU/mL lower than the Architect assay (LOA: -415.9, 389.3), while LOA between assays were much wider at higher levels (< 1000: -198.2, 147.9; ≥ 1000PEIU/mL: -688.4, 721.5). Further analysis indicated that d¯ did not change substantially with respect to HBV genotype, precore mutation, and CD4+ cell count, regardless of HBeAg-level. Nevertheless, seven of eight patients with highly divergent between-assay results had HBV-DNA> 2000IU/mL.

Elecsys and Architect assays report similar qHBeAg units with high correlation. Since qHBeAg was performed using an in-house approach, a commercially-available assay could reduce between-assay discrepancies, especially at higher HBeAg-levels.