Significant increase in 1-year posttransplant renal arterial index predicts graft loss.

BACKGROUND AND OBJECTIVES Conflicting data have been reported concerning the use of kidney graft arterial resistance index (RI) measured by Doppler to predict death-censored graft loss. We hypothesized that changes in RI values could carry better information than a single measure of RI. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Four hundred twenty-five renal transplant recipients were included in the study. We tested whether changes in renal arterial resistance index between 4 and 12 months after transplant (ΔRI(4→12)) were predictive of graft loss. RESULTS Neither 4-month nor 1-year RI predicted graft loss. The area under the receiver operating characteristics curve of ΔRI(4→12) for graft loss was 0.75. A ΔRI(4→12) ≥10% had the best sensitivity and specificity. One year after transplant, 22% of the study population had ΔRI(4→12) ≥10%. Fifty-five patients (12.9%) experienced graft loss during follow-up. The annual incidence of graft loss was higher in patients with ΔRI(4→12) ≥10% (3.5 versus 1.3%; P = 0.009). In multivariate analysis, patients with ΔRI(4→12) ≥10% had an increased risk of graft loss (hazard ratio, 6.21; 95% confidence interval, 1.99 to 22.15; P = 0.002). CONCLUSIONS A variation in RI ≥10% in the first year after transplant is an independent risk factor for death-censored graft loss in renal transplant recipients.