Interdonation intervals and patterns of return among blood donors in Brazil

Background: In Brazil, most donations come from repeat donors, but there are little data on return behavior of donors. Study design and methods: Donors who made at least one whole blood donation in 2007 were followed for 2 years using a large multicenter research database. Donation frequency, interdonation intervals, and their association with donor demographics, status, and type of donation were examined among three large blood centers in Brazil, two in the southeast and one in the northeast. Results: In 2007, of 306,770 allogeneic donations, 38.9% came from 95,127 first-time donors and 61.1% from 149,664 repeat donors. Through December 31, 2009, a total of 28.1% of first-time donors and 56.5% of repeat donors had donated again. Overall, the median interdonation interval was approximately 6 months. Among men it was 182 and 171 days for first-time and repeat donors, and among women, 212 and 200 days. Predictors of return behavior among first-time donors were male sex (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.13-1.20), community donation (OR, 2.26; 95% CI, 2.20-2.33), and age 24 years or less (OR, 0.62-0.89 for donors ≥25 years). Among repeat donors predictors were male sex (OR, 1.35; 95% CI, 1.32-1.39), age 35 years or more (OR, 1.08-1.18 vs. ≤24 years), and community donation (OR, 2.39; 95% CI, 2.33-2.44). Differences in return by geographic region were evident with higher return rates in the northeast of Brazil. Conclusion: These data highlight the need to develop improved communication strategies for first-time and replacement donors to convert them into repeat community donors.