BACKGROUND: Maintaining a stable blood supply is a critical goal of the American Red Cross Blood Services. Extensive Red Cross data provided the opportunity to assess both long-term and short-term trends in the variation of weekly blood donations. STUDY DESIGN AND METHODS: Overall trends and week-to-week variation in donation rates were assessed in volunteer, whole-blood donations from 1995 to 2005 among three Red Cross donor regions: the Connecticut region, the Greater Chesapeake and Potomac (Maryland) region, and the Southern California region, adjusting for population change, calendar time, age, sex, and donor region. RESULTS: Weekly donation rates varied widely by region, ranging from 3.5 donations per 10,000 persons in Southern California to 10.2 donations per 10,000 in Connecticut. Week-to-week variation in donation rates within each region was also quite high. Typical swings in weekly donation rates ranged from 38 percent in Connecticut to 56 percent in Southern California. Week-to-week variation was also 103 percent higher (95% confidence interval [CI], 87%-120%) among 18- to 24-year-old donors, compared to 25- to 44-year-olds, ranging from 32 to 49 percent. By comparison, week-to-week variation among adults 25 and older was more stable, ranging from 16 to 21 percent. CONCLUSION: This study suggests that there is a great deal of variation in donation rates, particularly among the youngest donors. Improving recruitment and retention among these donors will be critical to maintaining an adequate blood supply as the donor population ages.
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