PRISMA diagram depicting study flow through the review. *The number of studies does not sum to 180 across all objectives since a study may answer more than one objective. †The number of studies for each figure does not sum to the number of studies summarized since a study may be presented in different figures or multiple parts of a single figure. Not peer-reviewed: studies published in non-peer-reviewed journals (specifically Clinical Transplants and Transplantation Proceedings). Comparison not of interest: includes comparing various types or volume of transfusion (e.g. donor specific versus random); Outcome reporting: data for the outcome have not been reported in a format suitable for graphical representation (e.g. outcomes reported for one patient group only, outcome was drawn from a general conclusion in the text, time points were different from those selected for extraction [3, 6, 12, 24, 36, 60, 120, and 360 months], or outcomes were impacted by the different antibody detection techniques used in the study).