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.
Results: A total of 120 469 and 95 381 donors were included in the 2007 and 2013 cohorts, respectively. Compared to donors aged 20-24 years, the likelihood of return in both cohorts increased consistently as age at first donation increased from 30-years and above. Average number of whole-blood and plasmapheresis donations increased as the age at first donation increased from 30-years onward. The whole-blood donation rate was highest for donors >= 60 years, while plasmapheresis donation rate was highest for donors aged 50-59 years. These patterns were largely consistent when stratified by sex.
Conclusions: To continuously ensure the short- to mid-term sufficiency of blood supply in Australia, targeted recruitment of donors aged 30-years and above may be considered, however its feasibility and impact should be explored further given relatively smaller proportion of new donors are middle-aged and older under current policies. Future studies with a longer follow-up period are needed to examine whether the frequency of donation among those who start donating at a younger age increases later in their life when they are 30-years or over.