The role of quantitative HBsAg in the natural history of e antigen-negative chronic hepatitis B: A Tunisian prospective study

tBackground/Aims: During the natural course of Chronic Hepatitis B (CHB) infection, differentiationbetween inactive carrier (IC) and HBeAg negative CHB is a subject of ongoing debate. We studied therole of hepatitis B surface antigen (HBsAg) level as a means of differentiating between CHB and IC in agroup of untreated chronic HBeAg-negative HBV-infected patients. Study: A total of 115 HBeAg negative carriers were enrolled and followed up for > 12 months; 78 asinactive carriers (IC), and 37 as active carriers (AC). Among ACs, patients were categorized according tothe highest rate of viral load: AC1 (n = 23), active carriers with persistent HBV-DNA < 20,000 IU/mL; AC2( n = 14), active carriers with HBV-DNA > 20,000 IU/mL. Results: HBsAg levels were higher in AC compared to IC patients (1607 IU/ml vs. 225 IU/ml respectively, P = 0.001). Among the AC group, the 23 AC1 cases had HBsAg levels significantly lower than the 14 AC2patients (1756 IU/mL vs. 3327 IU/mL respectively; P < 10-3). HBsAg showed weak correlation with HBVDNA in the whole cohort (r = 0.44, P < 0.01). The suggested cutoff value of HBsAg titer to differentiatebetween the two groups was 938 IU/mL. Combined single-point quantification of HBsAg (938 IU/mL) andHBV DNA (2000 IU/mL) identified IC with 87.2% specificity and 91.7% positive predictive value. Conclusion: This study confirms the predictability of a one-time combined HBsAg and HBV DNA measurement for true inactive carriers requiring neither strict follow-up nor antiviral treatment.