Acyclovir/analogs & derivatives; Antiviral Agents/therapeutic use; Cytomegalovirus Infections/drug therapy; Graft Rejection/drug therapy; Kidney Transplantation/adverse effects; Postoperative Complications; Renal Insufficiency, Chronic/surgery; Valine/analogs & derivatives; Acyclovir/therapeutic use; Adult; Antibiotic Prophylaxis; Cytomegalovirus/genetics; Cytomegalovirus/pathogenicity; Cytomegalovirus Infections/etiology; Cytomegalovirus Infections/mortality; Female; Follow-Up Studies; Glomerular Filtration Rate; Graft Rejection/etiology; Graft Rejection/mortality; Graft Survival/drug effects; Humans; Kidney Transplantation/mortality; Male; Middle Aged; Prognosis; Retrospective Studies; Survival Rate; Time Factors; Valacyclovir; Valine/therapeutic use