Reducing Registry Members’ Attrition When Invited to Donate: Evidence from a Large Stem Cell Registry

Abstract

Attrition of stem cell donors at the confirmatory typing (CT) stage nontrivially reduces the supply of life-saving stem cell transplants. Using data from DKMS Germany, a major stem cell donor registry, we study a set of initiatives that collected donors’ genetic information or periods of temporary unavailability meant to enhance operating efficiency and registry members’ ultimate availability to donate. We analyzed 91,670 CT requests to registry members for whom a matching patient was found. We find that initiatives are robustly associated with lower attrition through both sorting and behavioral channels. Our preferred estimates indicate that the initiatives are associated with between 4.0 and 8.5 percentage point lower attrition, corresponding to 17.5–37.1 percent reduced unavailability to donate. Moreover, the decision of donors to engage in an initiative is predictive of their propensity for attrition at the CT stage. We discuss implications for stem cell registries in terms of operational efficiency, notably their ability to use participation in the initiatives as a signal of higher eventual availability to donate, as well as costs and benefits.