[Natural history of hepatitis B virus infection in dialysis patients: prospective study by quantitative analysis of HBV viremia]

Abstract

Background: The natural history of hepatitis B virus (HBV) infection in patients undergoing maintenance dialysis is still unclear. The aim of this study was to measure the HBV viral load (HBV DNA) in a cohort (n=20) of HBsAg positive chronic dialysis patients over a 12-month observation period. METHODS; HBV DNA was measured by the Amplicor HBV MonitorTM Test Kit, an in vitro test that utilizes Polymerase Chain Reaction (PCR) nucleic acid amplification and DNA hybridisation for the quantitative measurement of hepatitis B viral DNA in human serum. Amplicor HBV MonitorTM Test Kit amplifies a sequence in the pre-Core/Core region of the HBV genome with biotinylated and non-biotinylated oligonucleotide primers.

Results: There was no significant difference between the median HBV load at the start and the end of the study, 1.85 x 104 HBV copies/ml (percentile 16.84; 6.35 x 102 - 3.5 x 106 HBV copies/ ml) and 8.5 x 103 HBV copies/ml (percentile 16.84; 5.5 x 102 - 6.38 x 105 HBV copies/ml), respectively. These serum HBV DNA levels were lower than those measured by the same test in patients with chronic hepatitis B and normal renal function (Hepatology 2000; 32: 116-23). In the group of HBsAg positive carriers on dialysis, we identified three patterns of HBV viremia over time: 1) patients (n=6) with persistent HBV DNA, 2) those (n=2) with undetectable HBV DNA and 3) those (n=12) with intermittent HBV DNA. Patients with persistent HBV DNA (median, 3.3 x 104 HBV copies/ml; percentile 16.84; 3.5 x 103 - 2.3 x 106 HBV copies/ml) had higher viral HBV load than those with intermittent HBV viremia (median, 1.2 x 103 HBV copies/ml; percentile 16.84; 3.5 x 102 - 2.3 x 104 HBV copies/ml) (p=0.0001). Patients with persistent HBV DNA had higher frequency of serum hepatitis B e antigen (HBeAg) positivity than those showing intermittent and negative HBV DNA, 50% (3/6) vs. 0% (p=0.04). The frequency of serum IgM antibody against hepatitis B core antigen (IgM anti-HBc) was higher in patients with persistent HBV DNA than those having intermittent or negative HBV DNA, 100% (6/6) vs. 33% (4/12), p=0.03. We detected no difference in aminotransferase activity between patients with persistent HBV DNA and those showing intermittent or negative HBV DNA. In the group with persistent HBV DNA, the mean difference between maximum and minimum values of HBV DNA observed in each individual patient was 6.13+/-1.25 decimal logarithm (Log10) and in patients with intermittent HBV DNA 3.87+/-1.49 Log10 (p=0.006). In the entire group, the fluctuations in HBV DNA values over time between and within individuals were not significant.

Conclusions: The viremic HBV load was low and relatively stable over a 12-month follow-up period; three patterns of HBV viremia over time were observed; 30% of the viremic patients had persistent HBV viremia, and those patients had larger viral load and higher frequency of HBeAg and anti-HBc IgM than did patients with intermittent or negative HBV DNA. Prospective studies with longer observation periods are in progress to fully understand the natural history of HBV in these immunosuppressed patients.