Introduction: The resistive index (RI) obtained by performing doppler sonography is a hemodynamic index commonly used to measure flow resistance within an organ to assess if there is a vascular disease associated with that organ. It is a well-known predictor of kidney transplant outcome. The purpose of this study was to analyze the impact of RI values on patient and graft survival, as well as kidney graft function during 5-year follow-up.
Materials and methods: We retrospectively investigated 761 kidney transplant recipients from cadaveric donors performed between 1998 to 2011. RI was measured at hospital discharge after the kidney transplant. All the patients were divided into tertiles, according to the baseline RI value (group 1: RI < 0.70, group 2: RI between 0.70 and 0.79 and group 3: RI > 0.80).
Results: Patients with a low RI (<0.70) showed the lowest incidence of delayed graft function (DGF) compared to the other two groups (20.2% vs. 32.2% vs. 33%). Recipients with low RI values displayed significantly better creatinine clearance (70 vs. 55 vs 35 ml/min, respectively) than those with medium or high RI values at 5-year follow-up. Kaplan-Meier estimates of cumulative graft survival were significantly worse in patients who had a RI of 0.70 or more than in patients with a RI of less than 0.70 (p = 0.02). Cumulative patient survival showed the same behavior (0.01)
Conclusions: Low RI values measured in segmental arteries in the very early post-transplant period predict better kidney graft function and reduce the risk of all-cause graft loss, including patient death in a 5-year follow-up period.