BACKGROUND.: Sirolimus (SRL) is an important component of clinical immunosuppression in renal transplantation, but few international studies have examined how this agent is used in routine practice. METHODS.: Within a large prospective pharmacoepidemiological study, 718 de novo renal graft recipients treated with SRL in 65 centers in 10 countries were monitored for up to 5 years posttransplant to compare the principal outcomes and adverse effects by treatment regimen. RESULTS.: Principal treatment regimens were SRL without a calcineurin inhibitor (33%), SRL+cyclosporine A (CsA) (33%), and SRL+tacrolimus (TAC) (34%); 18% of subjects discontinued SRL, 124/718 (17%) developed biopsy-confirmed acute rejection (BCAR), 64/718 (9%) lost their graft, and 50/718 (7%) died during follow-up. Calculated creatinine clearance was 66+/-26 mL/min at 2 years. The most common adverse events were hypertension, hyperlipidemia, anemia, urinary tract infections, and diabetes. BCAR was significantly lower in subjects receiving SRL+TAC (hazard ratio [HR] 0.46, P=0.009) but not significantly lower in those receiving SRL+CsA (HR 0.62, P=0.102) compared with SRL without a calcineurin inhibitor. Graft loss or death did not significantly differ between treatment groups but were associated, respectively, with deceased donor grafts (HR 3.33, P
