Trajectories of serum hepatitis B surface antigen kinetics in patients with chronic hepatitis B receiving long-term nucleos(t)ide analogue therapy.

Background & Aims The kinetics of serum hepatitis B surface antigen (HBsAg) levels during long-term nucleos(t)ide analogue (NA) therapy in chronic hepatitis B (CHB) patients remains unclear. We investigated the patterns of serum HBsAg kinetics and their association with therapeutic outcomes in genotype B- or C-infected CHB patients receiving long-term NA therapy. Methods We enrolled 329 treatment-naive CHB patients receiving NA therapy for >5 years to analyse the kinetic patterns by using group-based trajectory models (GBTMs). Results Most patients (82.4%) received entecavir therapy. The median treatment duration was 83.6 (68.5-89.7) months. The GBTMs revealed three groups for both the hepatitis B e antigen (HBeAg)-positive and -negative patients. The median annual decline in serum HBsAg levels during the first 5 years was significantly higher in Group 1 than in Groups 2 and 3 in HBeAg-positive (0.78 vs 0.10 vs 0.10 log10IU/mL) and HBeAg-negative (0.71 vs 0.08 vs 0.09 log10IU/mL) patients. HBsAg levels at the baseline and 12 months combined with an HBsAg decline from the baseline to 12 months of treatment predicted trajectory pattern 1 in HBeAg-positive (sensitivity, 77.8%; specificity, 99.1%; positive predictive value [PPV], 87.5%; and negative predictive value [NPV], 98.2%) and HBeAg-negative (sensitivity, 100%; specificity, 99.5%; PPV, 88.9%; and NPV, 100%) patients. The trajectory patterns were significantly associated with HBeAg loss in the HBeAg-positive patients and the achievement of HBsAg <100 IU/mL or HBsAg loss in HBeAg-positive and HBeAg-negative patients. Conclusions The trajectory of serum HBsAg levels predicts HBsAg loss in CHB patients receiving long-term NA therapy.