Deferring blood donors who admit to high-risk behavior on questioning are likely to eliminate those in window period for transfusion transmitted infections (TTI). However, many questions have been implemented in some countries as part of donor history questionnaire, based on precautionary principle and not on evidence, and can result in increased donor losses. This study aims to identify effective risk-directed questions having high predictive value, in local context which can form part of blood donor deferral policies. For this, a case control study in a hospital blood bank having donation services was carried out prospectively over a period of three years.
Materials and Methods:
Two hundred and twenty donors, who were repeatedly reactive for HBsAg, anti-HCV, anti-HIV with EIA, and syphilis with TPHA, were the cases. Eight hundred and eighty four controls were the donors who tested negative for all TTI test. All donors answered seven hepatitis risk directed questions and their responses and reactivity status for TTI were used for statistical analysis with SPSS ver. 15.
Positive predictive value for history of jaundice at any age for HBsAg was 20%, while PPV for history of surgery in previous six months for both HBsAg and anti-HCVHCV was also around 20%, based on pretest probability of 7%. The post-test probability for these questions was around 30%. Odds ratios with 95% CI did not reveal any significant association of hepatitis with any of seven questions. Donor losses after deferring on basis of two questions were 5.3% per year, while deferral rate after all seven questions was 20%.
Donors should be permanently deferred if there is history of jaundice at any age, while deferral period after surgery should be one year. Other risk-directed questions should not be used to defer donors. Donor deferral policies should be evidence based and questions with proven efficacy should be made part of donor history questionnaire to minimize donor losses.