[Serum hepatitis B markers in blood donors in Venezuela. What do they mean?].

PURPOSE: The prevalence of serum BH markers is high in our country. In order to assess the factors of impact in this fact a group of blood donors with positive BH markers attending our Service between 1-1-95 and 12-31-96 was evaluated, although the endemic character of the disease may be an obstacle for its recognition. The residual risk of HBV transmission by seronegative transfusions was also evaluated.

MATERIAL AND METHODS: The evaluation of donors was performed by surveying identification data, type and frequency of donations and risk factors. The following reagents were used to carry out the bests: Biotest Elisa HbsAgand Heprofile anti HBc, ADI Diagnostics (1995), and Abbott Auzyme Monoclonal and Abbott Corzyme Diagnostic kit. Positive donors were re-evaluated to determine any progression of the disease and they were classified into false positive (FP), chronic carriers (CC), acute hepatitis (AH), naturally immunized (NI), or without evidence of immunity (WI). The residual transfusional risk was calculated by multiplying the adjusted prevalence of HbsAg positive donors by the window period expressed in fractions of a year.

RESULTS: Out of 53,338 donations, 5.91% were discarded due to the presence of HBV, 7.5% of them showing significant association with other markers: HCV, Chagas' disease and syphilis. Of all donors 223 (7.54%) returned for re-evaluation, and only 139 (62.33% of them) could be fully evaluated as follows: FP 10.09%, AH 5.76%, CC 7.19%, NI 68.35%, WI 7.91%. Their mean age was 35.73 +/- 9.95 years, and there were 112 males and 12 females. The donations were patient-related in 93.5% of cases, voluntary in 3.22% and coming from mobile units in 3.22% of instances (p = 0.067). Fifth per cent donated for the first time, and the other 50% had donated previously although not in a consecutive way (p = 0.96): 46% were ignorant of their post-donation findings, 37.09% were seemingly negative and 16.12% had positive tests. Of these last, the reasons for donation included defective questioning and information (50%), results not verified (20%) and family/hospital pressure (30%). Homo/bisexuality and drug abuase (not intravenous) were found significant when associated to each other or to promiscuity. Promiscuity attained significant risk value, especially when previous venereal disease or close contact with BH patients were presented (p = 0.0015, p = 0.155, and p = 0.0036, respectively). The residual risk of transmitting HBV by seronegative transfusions was found to be: 1:437.

CONCLUSIONS: 1. No risk factors were detected in a half of the cases. 2. The other half, comprising the known seropositive subjects and the promiscuous, homo/bisexual donors and those having close contact with HBV patients, can be discarded predonation. 3. Drug abuse (not intravenous), frequently associated with other risk factors, should discard a donor. 4. History of veneral disease should be considered a risk factor due to its common association to HBV. 5. The residual risk of acquiring HBV post-transfusion is still high.

RECOMMENDATIONS: 1. To improve the information provided to donors regarding the risk factors. 2. The interrogation should be simple, direct and deep. 3. To insist in the importance of the donor returning for his/her credentials in the blood bank and to know about any altered results, and to seek medical advice when appropriate. 4. To change related donation into a voluntary and consecutive pattern.