Long-term return and donation pattern of those who begin donating at different ages: A retrospective cohort analysis of blood donors in Australia.

Background: This study compared the likelihood of return to donate and donation rate ratio by age of donors at their first donation when followed up to 12 years.

Study Design And Methods: Donation history of two cohorts of first-time donors (those donating in 2007 and 2013) was extracted until March 2019 from Australian Red Cross Lifeblood's national database. Poisson regression analyses compared donor return and negative-binomial regression estimated the rate ratio of donations.