Association of donor age, body mass index, hemoglobin, and smoking status with in-hospital mortality and length of stay among red blood cell-transfused recipients.

We found no evidence of associations between blood donor factors and in-hospital mortality. Our finding of shorter hospital length of stay in patients transfused RBCs from younger donors is intriguing but requires confirmation. Future collaborations are needed to develop a framework of appropriate methodologic approaches to be used in linked analyses across large cohorts.