title: Increasing blood availability by changing donation patterns.
abstract: BACKGROUND
  There is a declining margin between US blood collections and transfusions. Donation patterns were examined to characterize returning first-time donors and predict the impact on blood availability of decreasing the number of nonreturning donors.
  
  
  METHODS
  First-time donors giving between 1991 and 1994 were followed for 3 to 6 years. The impact of decreasing the number of nonreturning donors in a 12-month period was projected using the Poisson distribution to model the donation patterns of 539,063 donors who gave in 1995. Repeat donors were classified as "returning first-time" (gave a first-time donation within 12 months of their index donation), "established" (gave a repeat donation), and "inactive" (didn't donate in the 12 months before their index donation).
  
  
  RESULTS
  A total of 49 percent of first-time donors did not return within 6 years. Returning first-time donors tended to be US born, white, and had more than a high school education. In 1995, 30 percent of donors were first time, 31 percent were established, 7 percent were returning first time, and 32 percent were inactive, giving 1.5, 2.4, 1.9, and 1.7 donations in 12 months, respectively. Reducing nonreturning donors by 5 percent could increase blood collections by 2.7 percent. Similarly, 15 or 25 percent reductions in nonreturns could increase collections by 8.6 or 16.0 percent, respectively.
  
  
  CONCLUSIONS
  Most donors are not giving near the donation limit. A substantial increase in donations could be achieved by a relatively small decrease in donor nonreturn. Research is needed to understand why approximately half of first-time donors donate only once.
authors.affiliation: Westat, Inc., 1650 Research Blvd., Rockville, MD 20850, USA. georgeschreiber@westat.com
authors.forename: George B
authors.initials: GB
authors.lastname: Schreiber
authors.forename: Ana M
authors.initials: AM
authors.lastname: Sanchez
authors.forename: Simone A
authors.initials: SA
authors.lastname: Glynn
authors.forename: David J
authors.initials: DJ
authors.lastname: Wright
mesh_terms: D001519:Behavior; D001782:Blood Donors / Q000523:psychology / Q000706:statistics & numerical data*; D006801:Humans; D010560:Personnel Selection