From December 1, 2007, through September 30, 2009, CPRA was used if greater than 0; otherwise, the maximum pretransplant PRA was used. Before December 1, 2007, the maximum pretransplant PRA was used unconditionally. CPRA is used after September 30, 2009, unless it is missing; if it is missing, the maximum pretransplant PRA is used. Kidney-alone transplants only.