Zinc sulfate and immunologic response to recombinant hepatitis B vaccine Patients and Methods In a clinical trial conducted at Imam Reza Hospital, the main referral center in western Iran in Kermanshah province, from 140 subjects over 40 years old, 102 that were negative for HBcAb (measured by competitive ELISA, Biomerieux, USA), enrolled into this study and randomly allocated into two intervention and control groups. Subjects were given detailed information about the study and written informed consent was obtained. A questionnaire including information regarding demographic factors, history of exposure to hepatitis B, any previous allergy, history of pervious hepatitis B vaccination was completed by trained interviewers. The intervention group was given hepati- tis B vaccine (Hepavax, Korea) plus 200 mg zinc sulfate capsule (Alhavi, Iran); the control group was given hepatitis B vaccine (Hepavax, Korea) plus placebo (capsule filled by sugar). Three vaccination injections were given intra-muscularly using rapid method on the first day, and the next 10 days following, and fi- nally in 22 days after the first injection (9) Anti-HBs antibody was measured by competitive ELISA (Biomerieux, USA) at the same hospital lab one month after the last vaccine injection in both groups. For the purpose of this study with assumption of 60% and 90% of people who reached to the protective level in control and trial group, we calculated a sample size of 102 people for the study to be able to reject the hypothesis that the propor- tion for trial and control groups are equal with a study power of 0.95. Type I error probability was set to 0.05. Uncorrected x2 test was used to test the hypothesis. Statistical analyses were performed using Stata ver 8. A p<0.05 was considered statisti- cally significant. Mean serum antibody between two groups was compared by Student’s t test. To compare the number of people who were immune after vaccination in two groups we used x2 test. Using univariate and multivariate logistic regression, we investigated the effect of different factors on seroconversion. Results The subject of this study included 52 women (51.0%) and 50 men (49.0%). Out of the 102 participants, seven (6.9%) were ciga- rette smokers (4% in the intervention and 9.6% in the control group). From 102 participants, 50 in the trial group received zinc sulfate with three injections of the vaccine. The median Table 1. Comparison of characteristics and Ab level among the two groups Variable WithZinc(n=50) WithoutZinc(n=52) p-value Gender 50 (Female %) Age (Mean±SD, year) 49.1±8.0 Smoking (%) 4.0 BMI 25.8±2.0 Ab level 116.93 (mIU/mL) Immunity (%) 26.0 51.9 48.4±8.3 9.6 25.2±2.3 157.37 36.5 0.85 0.67 0.26 0.14 0.22 0.25 Table 2. Effect of different factors on immunity after hepatitis B vaccination us- ing logistic regression analysis. Variable Univariateanalysis(95% CI) Multivariateanalysis(95% CI) Gender 1.9 (0.84–4.7) (Female) Age 0.95 (0.89–1.0) Smoking 0.87 (0.16–4.7) BMI 0.92 (0.76–1.11) Group 0.61 (0.26–1.42) (trial) 1.68 (0.66–4.26) 0.96 (0.91–1.0) 0.95 (0.19–5.9) 0.91 (0.74–1.12) 0.64 (0.26–1.56) Afsharian M et al. 33 age of participants was 47 (range: 40–73) years. There were no statistical significant differences between the intervention and control groups in terms of main confounding and background variables such as gender, age and smoking habits and body mass index (BMI) (all p>0.1) (Table 1). Comparing mean antibody level and the proportion of people who reached the protective level, both groups were similar (Table 1). While the distribution of male and female participants among trial and control groups was similar (Table 1), in both groups slightly greater proportion of females reached the protective level (Figure 1). Similar find- ings were observed when we compared the mean of natural log- arithm of antibody level in two sexes in both groups (3.2±2.3 and 3.3±2.0 among males in the control and intervention groups, re- spectively, and 3.8±2.4 and 3.1±2.3 among females in the control and trial groups, respectively). While the proportion of smokers among two groups was similar (Table 1), smoking has no signifi- cant effects on the proportion of immunized people after three vaccine injections (Table 2). None of smokers in the trial group developed the protective antibody level (Figure 2). The mean age among the studied groups was also similar (Table 1). Although non-statistically significantly, the proportion of protected peo- ple decreased by growing age in both univariate and multivari- able analyses (Table 2). Figure 3 shows the mean of log Ab level in both groups by age. Table 2 shows the result of univaritate and multivariate analyses of all variables including “group” on final immunity after three vaccine injections. After adjustment, none of the studied variables had effect on immunity. Figure 1. Percentage of immunized people among two sexes Figure 2. Percentage of immunized people among two sexes Hepat Mon. 2011;11(1):32-35