RESUMEN
BACKGROUND AND OBJECTIVES: Few longitudinal studies have examined the long-term effect on deferral for low haematocrit (Hct) or haemoglobin, indicators of presence of anaemia. This study retrospectively analysed 11 years of donation history to examine predictors related to such deferrals among repeat blood donors. MATERIALS AND METHODS: We included 385,357 donors with at least two visits to the blood centre between January 1996 and December 2006 who were not deferred due to haematocrit at their first visit. We evaluated variables related to the development of low Hct (LHct-below 38% for females and 39% for males) after whole blood donations. RESULTS: Over the 11-year period, 3,850 (1.5%) of the 252,301 males and 18,104 (13.6%) of the 133,056 females were deferred due to LHct at some point after their first donation. Genders, age, baseline Hct, Hct at the visit immediately before deferral due to LHct, and interval between donations, were associated with higher rates of development of LHct in repeat donors. CONCLUSION: Our analysis showed that deferral due to low Hct levels in repeat blood donors is highly prevalent in Brazil. Assigning longer donations intervals based on the Hct levels at the qualifying donation or supplementing iron to donors at risk may decrease deferral rate of donors with low Hct.