Fig. 2
a The scatter plot of HBV DNA and HBsAg levels in the model construction cohort. b Backward stepwise linear regression analysis in patients with HBV-DNA ≤ 6 log10 IU/mL. The x-axis showed the number of variables incorporated in the model, which also equated to the degrees of freedom in the F-test. The y-axis showed the P values calculated by the F-test. At the beginning, all 16 clinical variables were incorporated into a linear model. Less relevant variables were progressively removed. At the end of the stepwise process, a linear combination of platelet and HBV DNA levels showed significant association to HBsAg levels (P = 0.048, degrees of freedom = 2). c Estimated HBsAg levels is a function of HBV DNA levels and platelet counts in the constructed biphasic model. d A scatter plot of the measured and estimated HBsAg levels in two validation cohorts. Validation cohort 1: patients with biopsy-included pretreatment evaluations. Validation cohort 2: treatment naïve patients