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Flowchart of study inclusion. G1 indicates the recipient age is less than 55 years and the donor age is less than 40 years; G2 indicates the age of the recipient is less than 55 years old and the age of the donor is more than 40 years old; G3 indicates the age of recipient is more than 55 years old and the age of donor is less than 40 years old; G4 indicates the age of recipient is more than 55 years old and the age of donor is more than 40 years old.
