The position and guidelines of the World Health Organization (WHO) and several national blood collection agencies for nearly 40 years have been based on the view that offering economic incentives to blood donors is detrimental to the quantity and safety of the blood supply. The guidelines suggest that blood should be obtained from unpaid volunteers only.
However, whether economic incentives positively or negatively affect blood donations (and other prosocial activities) has remained the subject of debate since the positions were established.
Evidence consistent with the WHO position came originally from uncontrolled studies using nonrandom samples and, subsequently, from surveys and laboratory studies indicating that economic incentives can “crowd out” (decrease) intrinsic motivations to donate and can attract “worse” donors.