692 ESTABLISHMENT OF INDIVIDUAL PREDICTION MODEL FOR TREATMENT RESPONSE IN HB E ANTIGENPOSITIVE CHRONIC HEPATITIS B PATIENTS ON LAMIVUDINE MONOTHERAPY

Background: Although the emergence of lamivudine-resistant strains is becoming a problem in the treatment of chronic hepatitis B (CHB), lamivudine is still the first-line drug in many countries, because of its long-term safety profile and relatively inexpensive cost.Hence, it would be helpful to screen lamivudine responders either prior to, or in the early period of lamivudine treatment.The aim of this study was to establish an individual prediction model (IPM) for HBeAg seroconversion in HBeAgpositive CHB patients on lamivudine monotherapy.Methods: In this multi-center trial, we retrospectively analyzed 748 consecutive patients (Male: Female, 570:178) with HBeAg-positive CHB patients on lamivudine monotherapy from 7 medical institutions in Korea, from January 1999 to August 2004.The mean age was 42.5 years (range, 19-79).Univariate and multivariate analyses were conducted to identify factors associated with HBeAg seroconversion, and Risk Index (RI) for HBeAg seroconversion was calculated in a logistic regression model.Serum HBV DNA was detected by the Digene Hybrid Capture II HBV DNA Test (cut-off value = 1.4×10 5 copies/mL). Results:The median duration of lamivudine monotherapy was 30 months (range, 12-100).The cumulative HBeAg seroconversion rates were increased from 26.1% at 1 year to 50.7% at 8 years.The predictive factors for HBeAg seroconversion were age 40 years, pretreatment serum ALT >5× ULN, pretreatment serum HBV-DNA 8.0 log 10 copies/mL, and undetectable serum HBV-DNA at 12th week.Based on the above predictive factors of 748 HBeAg positive CHB patients, the IPM was calculated by formula as follows RI for HBeAg seroconversion = e A , A = 2.8844 + [-0.0262 × Age (years)] + [0.000915 × ALT (IU/L)] + [-0.2889 × DNA (log 10 copies/ml)].The probability of HBeAg seroconversion [RI/(1+RI)] was classified into high (>50%), intermediate (30-50%), and low ( 30%) response group.According to IPM, the rates of undetectable serum HBV-DNA at 12th week of lamivudine treatment were decreased 78.2%, 66.1%, and 46.4%, respectively.Conclusion: We have developed an IPM according to predictive factors for HBeAg seroconversion in HBeAg-positive CHB patients on lamivudine monotherapy.This model may help screening lamivudine responders either prior to, or in the early period of lamivudine treatment.