title: Intrarenal resistive index after renal transplantation.
abstract: BACKGROUND
  The intrarenal resistive index is routinely measured in many renal-transplantation centers for assessment of renal-allograft status, although the value of the resistive index remains unclear.
  
  
  METHODS
  In a single-center, prospective study involving 321 renal-allograft recipients, we measured the resistive index at baseline, at the time of protocol-specified renal-allograft biopsies (3, 12, and 24 months after transplantation), and at the time of biopsies performed because of graft dysfunction. A total of 1124 renal-allograft resistive-index measurements were included in the analysis. All patients were followed for at least 4.5 years after transplantation.
  
  
  RESULTS
  Allograft recipients with a resistive index of at least 0.80 had higher mortality than those with a resistive index of less than 0.80 at 3, 12, and 24 months after transplantation (hazard ratio, 5.20 [95% confidence interval {CI}, 2.14 to 12.64; P<0.001]; 3.46 [95% CI, 1.39 to 8.56; P=0.007]; and 4.12 [95% CI, 1.26 to 13.45; P=0.02], respectively). The need for dialysis did not differ significantly between patients with a resistive index of at least 0.80 and those with a resistive index of less than 0.80 at 3, 12, and 24 months after transplantation (hazard ratio, 1.95 [95% CI, 0.39 to 9.82; P=0.42]; 0.44 [95% CI, 0.05 to 3.72; P=0.45]; and 1.34 [95% CI, 0.20 to 8.82; P=0.76], respectively). At protocol-specified biopsy time points, the resistive index was not associated with renal-allograft histologic features. Older recipient age was the strongest determinant of a higher resistive index (P<0.001). At the time of biopsies performed because of graft dysfunction, antibody-mediated rejection or acute tubular necrosis, as compared with normal biopsy results, was associated with a higher resistive index (0.87 ± 0.12 vs. 0.78 ± 0.14 [P=0.05], and 0.86 ± 0.09 vs. 0.78 ± 0.14 [P=0.007], respectively).
  
  
  CONCLUSIONS
  The resistive index, routinely measured at predefined time points after transplantation, reflects characteristics of the recipient but not those of the graft. (ClinicalTrials.gov number, NCT01879124 .).
authors.affiliation: From the Departments of Nephrology and Renal Transplantation (M.N., L.H., K.C., D.K., P.E., B.B., B.S., B.M., H.J., C.M., K.D.V., Y.V.), Pathology (E.L.), Radiology (L.D.W., F.C., R.O.), and Abdominal Transplant Surgery (J.P., D.M.), University Hospitals Leuven, and the Departments of Microbiology and Immunology (M.N., K.C., D.K., P.E., B.B., B.S., B.M., J.P., D.M., K.D.V., Y.V.) and Imaging and Pathology (E.L., L.D.W., F.C., R.O.), KU Leuven - both in Leuven, Belgium.
authors.forename: Maarten
authors.initials: M
authors.lastname: Naesens
authors.forename: Line
authors.initials: L
authors.lastname: Heylen
authors.forename: Evelyne
authors.initials: E
authors.lastname: Lerut
authors.forename: Kathleen
authors.initials: K
authors.lastname: Claes
authors.forename: Liesbeth
authors.initials: L
authors.lastname: De Wever
authors.forename: Filip
authors.initials: F
authors.lastname: Claus
authors.forename: Raymond
authors.initials: R
authors.lastname: Oyen
authors.forename: Dirk
authors.initials: D
authors.lastname: Kuypers
authors.forename: Pieter
authors.initials: P
authors.lastname: Evenepoel
authors.forename: Bert
authors.initials: B
authors.lastname: Bammens
authors.forename: Ben
authors.initials: B
authors.lastname: Sprangers
authors.forename: Björn
authors.initials: B
authors.lastname: Meijers
authors.forename: Jacques
authors.initials: J
authors.lastname: Pirenne
authors.forename: Diethard
authors.initials: D
authors.lastname: Monbaliu
authors.forename: Hylke
authors.initials: H
authors.lastname: de Jonge
authors.forename: Christoph
authors.initials: C
authors.lastname: Metalidis
authors.forename: Katrien
authors.initials: K
authors.lastname: De Vusser
authors.forename: Yves
authors.initials: Y
authors.lastname: Vanrenterghem
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001706:Biopsy; D001783:Blood Flow Velocity; D005260:Female; D006084:Graft Rejection / Q000276:immunology / Q000503:physiopathology; D006085:Graft Survival / Q000502:physiology*; D006801:Humans; D007668:Kidney / Q000098:blood supply / Q000473:pathology; D007677:Kidney Function Tests; D016030:Kidney Transplantation / Q000000981:diagnostic imaging / Q000473:pathology / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011379:Prognosis; D011446:Prospective Studies; D011673:Pulsatile Flow; D012077:Renal Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D018608:Ultrasonography, Doppler; D014655:Vascular Resistance