Longitudinal profiles of highly sensitive hepatitis B surface antigen levels: re-evaluation of HBsAg seroclearance

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Abstract

Background & Aims:

Serologic profiles after hepatitis B surface antigen (HBsAg) seroclearance in chronic hepatitis B (CHB) have not been well-studied.

Methods:

We employed a highly sensitive HBsAg (hs-HBsAg) assay (lower detection limit 0.5 mIU/ml), 100 times more sensitive than conventional HBsAg measurements. CHB patients achieving HBsAg seroclearance defined by conventional assays were followed up for serum hs-HBsAg, HBV DNA and antibody to HBsAg (anti-HBs) levels at 0 months, 6–12 months and 3–5 years after HBsAg seroclearance. Factors associated with hs-HBsAg detectability were determined.

Results:

One hundred and nine patients were recruited; 94 (86.2%) were followed up to years 3–5; and 25 patients (22.9%) were on nucleoside analogue therapy for a median duration of 6.0 (range 1.5–12.7) years before HBsAg seroclearance. Detectable hs-HBsAg was noted in 88 (80.7%), 60 (55.0%) and 20 (21.3%) patients at 0 months, 6–12 months and 3–5 years respectively. At years 3–5, genotype B patients, when compared to genotype C patients, had a higher anti-HBs positive rate (63.2% and 41.1% respectively, P = 0.036). Serum anti-HBs positivity, when compared to persistent anti-HBs negativity, was associated with a lower rate of hs-HBsAg detection (7.4% and 40% respectively, P < 0.001). Multivariate analysis showed anti-HBs negativity at years 3–5 to be independently associated with persistently positive hs-HBsAg (P = 0.007, odds ratio 7.1, 95% confidence interval 1.7–29.3).

Conclusion:

Serum hs-HBsAg could detect HBsAg presence in a substantial proportion of CHB after HBsAg seroclearance defined by conventional assays, especially among anti-HBs negative individuals. Serum hs-HBsAg could potentially assist differentiating HBsAg-negative CHB from individuals with only past HBV exposure without carrier state.

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