An estimate of blood donor eligibility in the general population.

To estimate the number of adults medically eligible to donate blood, the percent of the general population over the age of 16 deferrable by 13 current American Red Cross donor guidelines was calculated using the best available United States data. Categories examined included age, weight, hematocrit, pregnancy, blood pressure, heart disease, diabetes requiring insulin, male homosexual activity since 1977, intravenous drug use, sexual partner of high-risk group member, recent transfusion, history of cancer, and other (medical, surgical, travel history). Sex-specific total eligibility rates were estimated by serial multiplication of individual eligibility rates (1.0 minus deferral rates) to account for the proportionate overlap of independent categories, with corrections for expected associations between categories. The resultant eligibility rates for women (57%) and men (70%) indicate fewer eligible donors than commonly stated. Surrogate testing (ALT, anti-HBc) for non-A, non-B hepatitis would further reduce the percent of eligible donors to 55 and 67%, respectively. Based on the actual numbers of women and men in the population, these calculations indicate that an equal number of women and men are medically eligible to donate.