Renal artery stenosis: a resistance index of 80 or more predicted worsening renal function after treatment

Clinical bottom line (level 1b)

  1. One in four patients who 23re treated for renal artery stenosis developed worsening renal failure within 3 years.
  2. One in seven went on to require renal dialysis and one in ten died within 3 years.
  3. The risk of worsening renal failure was increased with
    • a resistance index of 80 or more
    • creatinine clearance < 40 ml/min
    and reduced with smoking
Radermacher et al: N Engl J Med 2001; 344 : 410-417
Expires June 2004

The study

Inception cohort study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: acute hospital, Germany

131 patients (aged mean 58, 55% male) with successful correction of renal artery stenosis

Factors studied:
  • resistance index, degree of renal artery stenosis,mean ambulatory 24 hours systolic and diastolic blood pressure, pulse pressure, nocturnal increased in bp, creatinine clearance, age, sex, activity, artherosclerosis, diabetes mellitus, smoking, serum uric acid concentrations, blood pressure response to ACE inhibitors, years since onset of hypertension, urinary protein excretion
  • resistance index 80 or more = [1 - (end-diastolic velocity/maximal systolic velocity)] x 100
  • creatinine clearance < 40 ml/min
  • smoking


Multivariate regression analysis was used to adjust for confounding factors.

100% followed for mean of 32 months

Outcomes studied:
  • fall in blood pressure < 10 mmHg
  • worsening renal function fall in creatinine clearance of 10% or more
  • requiring dialysis
  • death

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)    		 NNF
    (95% CI)
    fall in blood pressure < 10 mmHg 32 months 40/131 31%
    (23% to 38%)    		 3
    (3 to 4)
    worsening renal function 32 months 31/131 24%
    (16% to 31%)    		 4
    (3 to 6)
    requiring dialysis 32 months 19/131 15%
    (8.5% to 21%)    		 7
    (5 to 12)
    death 32 months 13/131 9.9%
    (4.8% to 15%)    		 10
    (7 to 21)

    prognostic factor for
    worsening renal function     		time to outcome control rate (%) adjusted OR
    (95% CI)    		 NNF+
    (95% CI)
    resistance index 80 or more 32 months 3/96
    (3.1%)     		1390
    (50 to 38400)     		1
    (1 to 2)
    creatinine clearance < 40 ml/min 32 months 12.7
    (1.7 to 95)     		2
    (1 to 9)
    smoking 32 months 0.04
    (0.0 to 0.5)     		-4
    (-10 to -4)

      Comments

      1. Resistance index 80 or more: LR + 13 (95% CI: 6.3 to 27), LR - 0.10 (95% CI: 0.036 to 0.31)

      Citation

      1. Radermacher J, Chavan A, Bleck J, et al: use of doppler ultrasonography to predict the outcome of therapy for renal-artery stenosis. N Engl J Med 2001; 344 : 410-417
      Search Terms: from reference list of systematic review
      Contributor: Chris Ball, June 2002
      Reviewer:

      Clinical Question.
      Patient treated for renal artery stenosis
      Intervention or Exposure resistance index, smoking, creatinine clearance
      Outcome worsening renal function, dialysis, death