Initial kidney graft resistance index and the long-term cardiovascular mortality in transplanted patients: a paired grafts analysis

Abstract

Background: Cardiovascular complications remain the most frequent cause of death in kidney transplant recipients. We analysed the prognostic value of early measured resistance index (RI) in the aspect of long-term cardiovascular mortality. In order to eliminate potential donor-related confounders, we analysed the mortality of recipients, transplanted with organs procured from the same donor, in whom the initial RI values substantially differed.

Methods: Doppler sonography was performed in 725 consecutive kidney graft recipients early after transplantation. We identified 133 pairs (266 patients) who received their kidney grafts from the same donor and their initial RI values differed by >0.1.

Results: During 109 ± 37 months of follow-up after transplantation, 84 patients lost their graft and 29 died, 14 of them due to cardiovascular causes. Two groups of paired patients with higher RI and lower RI did not differ significantly with respect to their age, BMI, HLA mismatch and cold ischaemia time. There were more patients with diabetes in the higher RI group (14.3 versus 6.8%). Survival analysis revealed a higher mortality for cardiovascular (8.3 versus 2.3%, P = 0.02) and all causes (14.3 versus 7.5%, P = 0.06) among patients with higher initial RI values. In the Cox regression model, not including age, a higher RI value was a strong predictor of cardiovascular death (HR = 4.88), independent of previous cardiovascular episodes (HR = 6.78). Both these variables lost its significance as a predictors after inclusion of age in the regression model.

Conclusion: Increased intrarenal resistance index in the early posttransplant period may help to identify the recipients with increased cardiovascular risk.

Keywords: Doppler ultrasound; cardiovascular death; kidney transplantation; outcome; predictor.