Hypercoagulable states in renal transplant candidates: Impact of anticoagulation upon incidence of renal allograft thrombosis

Introduction. Although multiple studies of demographic variables have been associated with allograft thrombosis, these results are not routinely repro ducible. Are ESRD patients with hypercoagulable states (HCS) (antithrombin III deficiency, protein S or C deficiency, activated protein C resistance, and anticardiolipin antibodies) at predictably greater risk for allograft t hrombosis? Methods. Between 1996 and 1999, all renal transplant candidates were screen ed for hypercoagulability risk factors [HRF] (multiple arteriovenous access thromboses, prior deep vein thrombosis, prior allograft thrombosis, collag en vascular disease, multiple miscarriages, diabetes, autoimmune disease, a nd Fabry's disease). HRF(+) candidates were then tested for HCS status. We administered preemptive posttransplant i.v. Heparin in HCS(+) patients and observed the impact of this intervention upon the incidence of allograft th rombosis. We compared demographic data and incidence of allograft thrombosi s in an historic control (346 patients transplanted between June 31, 1992, and March 5, 1996) not tested for HCS and a study cohort (502 patients tran splanted between March 6, 1996, and June 31, 1999) prospectively screened f or HRF. HRF(+) patients who were HCS(+) in the study cohort received i.v. h eparin immediately after transplant and p.o. warfarin as outpatients. Results. Demographic characteristics previously implicated in allograft thr ombosis were equivalently distributed in both cohorts with the exceptions t hat more living-donor transplants (33.1% vs. 15.3%) were performed in study cohort, CIT > 24 hr occurred in more control patients (37.3% vs. 22.1%) an d more study patients (16.7% vs. 0%) received tacrolimus. Hypercoagulable s tates were found upon reevaluating five of seven controls (71.4%), who lost prior allografts to thrombosis. Hypercoagulable states were prospectively detected in 10 study patients with hypercoagulability risk factors. Most (9 of 10) study patients receiving anticoagulation have achieved long-term al lograft function. Study group allograft thrombosis incidence was reduced (1 .59% vs. 4.05%). Hypercoagulable states were demonstrated in most episodes of allograft thrombosis. Control patients who lost prior allografts to thro mbosis were anticoagulated after retransplantation and 100% achieved longte rm allograft function. Conclusions. Long-term allograft function has been achieved in 90% of study patients when prophylactically anticoagulating study patients with hyperco agulable states. A 2.6-fold reduction in the expected incidence of allograf t thrombosis was observed in anticoagulated patients with hypercoagulable s tates.