Antiphospholipid antibodies as a risk factor for atherosclerotic events in renal transplant recipients

Background. Epidemiologic studies reported that antiphospholipid antibodies (APAs) were independent predictors of atherosclerotic events. We recently reported a high prevalence of APAs in renal transplant recipients. Nevertheless, the role of APAs on atherosclerotic events has not been prospectively studied in this high-risk population. Methods. Participants in the study were 324 consecutive renal transplant recipients. Patients were enrolled between January 1996 and May 1998 and followed up until June 2002. Results. The patients were followed for a mean duration of 62 +/- 26 months. Eighty seven (26.8%) patients exhibited APAs. We found a slight, but significant, correlation between total plasma homocysteine (tHcy) concentration and anticardiolipin (ACA) titers (r = 0.26; P = 0.036). Fifty six athersclerotic events (17.2%) occurred in 54 patients. Atherosclerotic events occurred more frequently in patients with APAs (33% vs. 9%; P = 0.0003) and ACAs levels were higher in patients who experienced atherosclerotic events (23.7 +/- 13.1 IU vs. 13.9 +/- 9.4 IU; P = 0.003). APAs were associated with an increased risk of atherosclerotic events (RR, 2.82; 95% CI, 1.17 to 5.31). Cox regression analysis also revealed that age above the median (RR, 5.21; 95% CI, 1.67 to 17.13), a previous history of cardiovascular disease (RR, 3.54; 95% CI, 1.57 to 10.43), hyperhomocysteinemia (RR, 4.01; 95% CI, 1.22 to 14.61), and current smoking (RR, 2.17; 95% CI, 1.01 to 6.72) were risk factors for atherosclerotic events. Conclusion. The presence of APAs is an independent cardiovascular risk factor in renal transplant recipients. Prevention trials are necessary to assess the efficacy and safety of anticoagulation therapy in transplant patients with APAs.