title: Do ultrasound renal resistance indices reflect systemic rather than renal vascular damage in chronic kidney disease?
abstract: BACKGROUND
  In patients suffering from chronic kidney disease (CKD), ultrasound renal resistance indices predict progression of kidney disease and death. Although ultrasound resistance indices were initially considered to directly reflect intrarenal vascular resistance, they are complex composite parameters that are influenced by various vascular factors. We hypothesized that renal resistance indices reflect systemic vascular disease rather than local renal damage in patients with CKD.
  
  
  METHODS
  In 140 patients suffering from CKD not receiving renal replacement therapy, intrarenal resistance indices were measured in interlobar arteries. For assessment of systemic atherosclerotic disease, common carotid intima-media thickness (IMT) and ankle-brachial blood pressure index were determined. Categories of risk for coronary heart diseases were defined by Framingham risk scoring.
  
  
  RESULTS
  Increased renal resistance indices were associated with high Framingham risk scores and with the presence of atherosclerotic disease. In addition, ultrasound renal resistance indices progressively increased with the stage of renal function impairment, and patients suffering from diabetic nephropathy had higher resistance indices than patients suffering from other renal diseases. In a multivariate linear regression analysis, IMT, Framingham risk score, renal function, presence of diabetic nephropathy and pulse pressure independently predicted resistance indices. However, when additionally adjusting for age, IMT and Framingham risk score were no longer independent predictors of resistance indices.
  
  
  CONCLUSIONS
  In patients suffering from CKD, intrarenal resistance indices are independently associated with cardiovascular risk score and systemic vascular disease as well as with aetiology and stage of CKD. This may explain their strong association with both impaired renal outcome and death.
authors.affiliation: Medical Department, Nephrology, University Homburg, D-66421 Homburg, Germany. inghei@uniklinik-saarland.de
authors.forename: Gunnar H
authors.initials: GH
authors.lastname: Heine
authors.forename: Birgit
authors.initials: B
authors.lastname: Reichart
authors.forename: Christof
authors.initials: C
authors.lastname: Ulrich
authors.forename: Hans
authors.initials: H
authors.lastname: Köhler
authors.forename: Matthias
authors.initials: M
authors.lastname: Girndt
mesh_terms: D000368:Aged; D001794:Blood Pressure; D001808:Blood Vessels / Q000473:pathology; D002318:Cardiovascular Diseases / Q000473:pathology; D002339:Carotid Arteries / Q000473:pathology; D005260:Female; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000473:pathology*; D007676:Kidney Failure, Chronic / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D012306:Risk; D012307:Risk Factors; D013997:Time Factors; D014463:Ultrasonography; D014652:Vascular Diseases / Q000150:complications / Q000473:pathology