Background:  The combination of lamivudine (3TC) and tenofovir (TDF) is increasingly used for coordinated treatment of both HIV and hepatitis B virus (HBV). Several studies demonstrated efficacy after a follow-up of 12 months, but little is known about the efficacy and safety during long-term treatment with 3TC and TDF in HIV/HBV-co-infected patients.

Methods:  During the period 2002 to 2006, HIV/HBV-co-infected patients in our institute who were treated with 3TC and TDF during at least 6 months were identified. We retrospectively collected data on patient characteristics, date of TDF initiation (baseline), CD4 cell counts and virological assessments at baseline and from collected stored sera. All available samples were tested on HBV genotype.  Statistical analysis was performed using the SPSS 11.5

Results:  We included 44 patients, of whom 39 were male, median age 38 years (26 to 58). Of these patients, 28 (63.6%) were 3TC-experienced (median period 49 months, range 4 to 111), of whom 10 had HBV DNA <1000 copies/mL at baseline. In 15 of the 18 remaining 3TC-experienced patients YMDD mutations were sequenced at baseline. HBeAg at baseline was positive in 29 of the entire 44 (65.9%) patients; median HBV DNA was 8.94 log₁₀ (Q1 – Q3:  6.03 to 9.45). At baseline 23 of 44 patients were HIV RNA undetectable with median CD4 cell counts of 255/mm³ (132 to 420). The median time of observed 3TC+TDF usage was 36 months (4 to 49). The percentage of patients with HBV DNA <1000 copies/mL at baseline and at 12, 24, and 36 months was 27%, 72%, 75%, and 86%, respectively. The median HBV DNA decrease after 36 months was 4.8 log₁₀. Serum HBeAg loss was observed in 12 of 21 (57%) HBeAg⁺ patients after HBV DNA suppression was established. In 1 patient the serum creatinine concentration increased (from 104 to 191 mM/L). Genotypic analysis was performed in 34 of 44 (77.3%) patients. The most frequently occurring genotype was A (56%), and 4 patients were co-infected with 2 or 3 genotypes (A/G and A/G/D). Univariate analysis did not result in predictive factors associated with achieving HBV DNA undetectability.

Conclusions:  Antiviral treatment of HBV in HIV/HBV-co-infected patients with a combination of 3TC+TDF showed to be safe and persistently effective in wild type HBV, precore mutants and 3TC-resistant with overall undetectable HBV DNA levels in 86% and loss of HBeAg in 57% of patients after a median follow-up of 36 months.