Source Department of Medicine, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul, Korea.

Background and Aim There is insufficient data on renal safety during long-term adefovir dipivoxil (ADV) treatment. We aimed to elucidate the incidence and risk factors of renal impairment in chronic hepatitis B (CHB) patients treated with ADV.

Methods We retrospectively enrolled 687 CHB patients (51.4% with compensated cirrhosis) treated with ADV alone (18.2%) or in combination with lamivudine (LAM, 81.8%) for more than 12 months. Renal function was measured using estimated glomerular filtration rate (eGFR), and renal dysfunction was defined as mild (20-30% decrease), moderate (30-50%), or severe (more than 50%).

Results During the median treatment duration of 27 months, 72 patients (10.5%) developed renal impairment, which was mild in 77.8% of cases, moderate in 20.8% of cases, and severe in one patient. The cumulative incidence of renal impairment at 1, 3, and 5 years was 2.6%, 14.8%, and 34.7%, respectively. Modification of the dosing interval or discontinuation of ADV was required in seven and three patients, respectively, and none of them showed further decline of eGFR. Although univariate analysis revealed age, the number of exposure to radio-contrast dye, liver cirrhosis, and hepatocellular carcinoma as risk factors of renal impairment, age was the only significant risk factor identified in multivariate analysis [ odds ratio = 1.048, 95% confidence interval = 1.019-1.076, p= 0.001).

Conclusions Renal impairment in long-term ADV users was relatively frequent, but serious renal toxicity was rare and all cases were safely managed. Careful monitoring of renal function is required, especially in older patients.