Challenges of using HIV as a primary risk indicator: Need for integrated blood donor risk management model

Background: The use of risk modelling in blood safety is increasing getting momentum. NBSZ initiated blood donor risk profiling based on donation frequency (r-coding) since 1994 and in 2006 a generic risk classification model was developed (include age and donation venue) which was mainly based on HIV risk considerations. The blood safety implications of this model, which include all the four routinely tested transfusion transmission infections (TTI) has not been studied. We aim to assess whether the use of HIV as a primary risk indicator is sufficient in Zimbabwe and the possible blood safety concerns for this. Methods: Blood donor data on HIV, HBV, HCV and Syphilis from 2002 to 2011 was analysed. The NBSZ blood donor risk model developed in 2006, which has four levels [RC I (lower) - RC IV (higher)] of blood safety, was evaluated based on the TTIs seroprevalence results. The TTIs relative risk (RR) for usable (RC I and II) and unusable (RC III and IV) were determined and 95% CI determined. Sub-group analysis by gender was also done to aid in explaining the results. Results: A total of 627,072 donations were analysed. The overall TTIs seroprevalence by donor risk category are shown in Table 1. NBSZ donor risk classification seems to be performing well for all TTIs except for HBV, which has highest seroprevalence in RC II. The overall relative risk (RR) for TTIs in risk categories for unusable units over usable units is 3.5 (95% CI, 3.3-3.8), 1.3 (1.2-1.3), 1.3 (1.1-1.5) and 2.1 (1.9-2.4) for HIV, HBV, HCV and Syphilis respectively. The average RR in all risk categories for males being TTI positive compared to females is 0.70, 1.95, 1.6 and 1.2 for HIV, HBV, HCV and Syphilis respectively. [TABLE PRESENTED] Discussion and conclusions: The results for HIV, HCV and Syphilis indicate increasing safety concerns from low (RC I) to high (RC II) as we expect the model to perform. However, the high HBV seroprevalence in RC II is of concern to blood safety as these are usable blood units. Further analysis also noted that in risk category II, which is mainly composed of new donors in schools, the HBV risk is 68% higher when compared with other combined risk categories. Males are 95%, 60% and 20% more likely to be positive for HBV, HCV and Syphilis than females. However, they are 30% less likely to be HIV positive when compared to female donors. In conclusion, our results points to blood safety concerns for HBV in Zimbabwe and hence there is need to review the current NBSZ blood donor risk classification model taking into consideration other TTIs and cost-effectiveness analysis.