Given the relatively low seroconversion rate and maintenance of protective hepatitis antibody levels among end-stage renal disease patients, a treatment strategy using various doses of recombinant hepatitis B vaccine (Engerix-B) has been recently explored. In an observational study, the investigators demonstrated no statistically significant difference in response rate between patients receiving three recommended doses of Engerix-B intramuscularly (40 micrograms each dose) and those with four times the normal adult dose (80 micrograms each dose), (78% versus 100%, P = 0.23). On the other hand, according to the Kaplan-Meier estimates, 78 percent of patients in the 40 micrograms Engerix-B vaccination group and 96 percent of patients in the 80 micrograms dosing group had maintained the seroprotective levels of antibody to hepatitis B surface antigen (anti-HBs) at 12 months after initial response. This difference corresponds to an absolute risk reduction of 18 percent for losing the antibody response with a three-dose schedule of 80 micrograms Engerix-B vaccination program. In other words, the investigators estimate that giving Engerix-B 80 micrograms dose would lead to one extra end-stage renal disease subject with persistent seroprotective anti-HBs level at one year for every 5.6 patients treated (number needed to treat to benefit NNT, 5.6; 95% confidence interval, 5.4 to 5.8).