The Resistive Index by Doppler Ultrasonography as a Predictor of the Long-Term Outcomes After Kidney Transplantation

Background: Doppler ultrasonography (US) is a noninvasive examination for assessing graft function after kidney transplantation. Although Doppler US is routinely performed, only a few reports have investigated whether a high resistive index (RI) detected by Doppler US affects graft function and survival. We hypothesized that there is a relationship between a high RI and inferior outcomes after kidney transplantation.

Methods: We included 164 living kidney transplant patients treated between April 2011 and July 2019. We divided the patients into 2 groups according to RI (cut-off, 0.7) 1 year after transplantation.

Results: The recipient was significantly older in the high RI (≥0.7) group. Moreover, there were significant differences in the prevalence of pretransplant diabetes mellitus and the value of pretransplant hemoglobin A1c. Regarding long-term outcome, there was no significant difference in overall graft survival (5 years, 92.6% vs 91.8%; 10 years, 85.0% vs 67.9%; P = .64). On the other hand, the mortality was significantly worse in the high RI group (5 years, 99.1% vs 93.9%; 10 years, 96.4% vs 70.0%, P = .013).

Conclusions: A high RI might predict mortality after kidney transplantation.