Objectiv     To investigate the clinical cure rate

influencing factors and optimal duration of interferon (IFN) treatment on chronic hepatitis B (CHB) patients with low HBsAg levels.  Methods     A total of 74 CHB patients with low HBsAg levels (HBsAg3 000 IU/mL) who received pegylated or conventional IFN treatment for at least 24 weeks in our department from January 2012 to August 2014 were enrolled in this retrospective study. The patients were divided into response group

partial response group and non-response group depending on the serum status of HBsAg and HBeAg at 24

48 and 72 weeks. Non-parametric test

Chi-square test and logistic regression analysis were used to comparatively study the baseline

HBV serum markers and other laboratory parameters between the response and non-response groups during the treatment.   Results     Twenty-five of 74 patients (33.8%) responded to the treatment till the drug withdrawal. The median baseline level of HBsAg in response group was lower than that of the nonresponse group (70.70 vs 440.71 IU/mL

P=0.041). Pegylated IFN (Peg-IFN) had a better effect on HBsAg clearance than conventional IFN (41.9% vs 22.6%

P=0.084). The decreased percentage of HBsAg quantitation at week 12 could predict the treatment efficacy at week 24 (OR=1.058，P=0.010). The area under the ROC curve was 0.860

cut-off value was 78.9

sensitivity was 0.889 and specificity was 0.815. Similarly

baseline level of HBV DNA and the decreased percentage of HBsAg quantitation at week 24 could predict the treatment efficacy at week 48 (OR=9.112，P=0.033；OR=1.089，P=0.006). The area under the ROC curve was 0.870

cut-off value was 69.7

sensitivity was 1 and specificity was 0.722. There was a positive liner relationship between HBsAg clearance rate and treatment duration within 48 weeks. Twenty-one of the 74 (28.4%) patients achieved response at week 48

which accounted for 84.0 % (21/25) of the total response patients at the end of treatment.  Conclusion     Our data indicate that clinical cure rate of IFN treatment is higher in patients with low HBsAg levels (HBsAg3 000 IU/mL) than those with high HBsAg levels. The curative efficacy of Peg-IFN is slightly better than conventional IFN with a recommended duration of 48 weeks. In addition

the level of HBsAg decline corresponds to the therapeutic efficacy

which provides guidance for the treatment duration.