Patients who had stopped treatment during EFFORT extension study could receive 2-year off-treatment follow-up. All the patients in Part I will be followed up at the interval of 12 weeks. For these patients, if they have hepatitis flare during follow-up, they will be re-treated with telbivudine combined with adefovir for the left study period ( the total study period is 2 years) and followed up at the interval of 12 weeks. Hepatitis flare is defined as HBV DNA>4 Log10 copies/mL with either ALT≥5 times upper limit of normal (ULN) or TBIL≥2×ULN，or 2 ≤ALT ≤5 ×ULN (at two consecutive visits at least 2 weeks apart) and total bilirubin (TBIL) <2×ULN.

Patients with continuous treatment during EFFORT extension study will continue treatment, without off-treatment rule in the further extension study. The treatment strategy is depended on the HBV DNA level of each individual, that is, for patients with negative HBV DNA level (defined as HBV DNA <20 IU/mL) will continue their previous treatment strategy; and for patients with positive HBV DNA level (defined as HBV DNA>=20 IU/mL) will receive the combination therapy of telbivudine and adefovir, irrespective of their previous treatment strategy. All the patients in Part II will be followed up at the interval of 24 weeks until they complete the 2-year on-treatment follow-up. Patients will be conducted liver biopsy at the sixth year of treatment. All the patients with telbivudine monotherapy will be switched to telbivudine plus adefovir once confirmed HBV DNA breakthrough developed.

Telbivudine, 600mg, oral, daily