Low-dose hepatitis B immunoglobulin given "on demand" in combination with lamivudine: a highly cost-effective approach to prevent recurrent hepatitis B virus infection in the long-term follow-up after liver transplantation.

BACKGROUND: Cost of long-term prophylaxis with high-dose human hepatitis B immune globulin (HBIg) after liver transplantation is extremely high. The aim of the present study was to assess consumption rates of high (5,000 IU) and low (2,000 IU) doses of HBIg given intravenously "on demand", and determine their cost-effectiveness compared with conventional fixed monthly schedules. METHODS: The study included 11 male patients (mean age 53 years) who received transplants for hepatitis B virus (HBV)-related cirrhosis 29 to 96 months earlier, all receiving lamivudine (100 mg/day) prophylaxis. Each patient received three consecutive intravenous infusions of 5,000 IU HBIg, followed by three 2,000 IU infusions. HBIg consumption was assessed by serial measurement of serum hepatitis B surface antibody (HBsAb) titer at 2-week intervals. HBIg was readministered only when HBsAb titers dropped below 70 IU/L (i.e., "on demand"). RESULTS: Mean HBsAb peak titers after high and low HBIg doses were 1,641 +/- 385 and 848 +/- 216 IU/L, respectively (P <0.0001). Mean time to reach an HBsAb titer less than 70 IU/L was 79.5 +/- 38.2 days versus 61.6 +/- 32.1 days, respectively (P =NS). Interindividual variation coefficients were 23 +/- 18% and 32 +/- 26% (5,000 IU and 2,000 IU, respectively). Using the on demand approach, maintenance of a protective anti-HBs titer required an average number of 4.0 (5,000 IU) and 5.6 (2,000 IU) HBIg administrations per year, respectively (P =NS). CONCLUSIONS: Individual HBIg consumption profiles are highly variable. A low-dose (2,000 IU) on demand HBIg administration schedule is highly cost-effective and provides more than 50% savings compared with conventional high-dose monthly schedules.