The effect of chronic renal insufficiency by use of glomerular filtration rate versus serum creatinine level on late clinical outcome of carotid endarterectomy.

BACKGROUND

Several studies have reported mixed results after carotid endarterectomy (CEA) in patients with chronic renal insufficiency (CRI), and we previously reported the perioperative outcome in patients with CRI by use of serum creatinine (Cr) level and glomerular filtration rate (GFR). However, only a few of these studies used GFR by the Modification of Diet in Renal Disease equation in their analysis of long-term outcome.

METHODS

During the study period, 1000 CEAs (926 patients) were analyzed; 940 of these CEAs had Cr levels and 925 had GFR data. Patients were classified into normal (GFR ≥60 mL/min/1.73 m(2) or Cr <1.5 mg/dL), moderate CRI (GFR ≥30-59 or Cr ≥1.5-2.9), and severe CRI (GFR <30 or Cr ≥3).

RESULTS

At a mean follow-up of 34.5 months and a median of 34 months (range, 1-53 months), combined stroke and death rates for Cr levels (867 patients) were 9%, 18%, and 44% for Cr <1.5, ≥1.5 to 2.9, and ≥3 (P = .0001) in contrast to 8%, 14%, and 26% for GFR (854 patients) of >60, ≥30 to 59, and <30, respectively (P = .0003). Combined stroke and death rates for asymptomatic patients were 8%, 17%, and 44% (P = .0001) for patients with Cr levels of <1.5, ≥1.5 to 2.9, and ≥3, respectively, vs 7%, 13%, and 24% for a GFR of ≥60, ≥30 to 59, and <30 (P = .0063). By Kaplan-Meier analysis, stroke-free survival rates at 1 year, 2 years, and 3 years were 97%, 94%, and 92% for Cr <1.5; 92%, 85%, and 81% for Cr ≥1.5 to 2.9; and 56%, 56%, and 56% for Cr ≥3 (P < .0001); vs 98%, 95%, and 93% for a GFR ≥60; 93%, 90%, and 86% for a GFR of ≥30 to 59; and 86%, 77%, and 73% for a GFR <30 (P < .0001). These rates for asymptomatic patients at 1 year, 2 years, and 3 years were 97%, 95%, and 93% for Cr <1.5; 94%, 87%, and 82% for Cr ≥1.5 to 2.9; and 56%, 56%, and 56% for Cr ≥3 (P < .0001); vs 98%, 95%, and 94% for a GFR ≥60; 95%, 91%, and 86% for a GFR of ≥30 to 59; and 84%, 80%, and 75% for a GFR <30 (P = .0026). A univariate regression analysis for asymptomatic patients showed that the hazard ratio (HR) of stroke and death was 6.5 (P = .0003) for a Cr ≥3 and 3.1 for a GFR <30 (P = .0089). A multivariate analysis showed that Cr ≥3 had an HR of stroke and death of 4.7 (P = .008), and GFR <30 had an HR of 2.2 (P = .097).

CONCLUSIONS

Patients with severe CRI had higher rates of combined stroke/death. Therefore, CEA for these patients (particularly in asymptomatic patients) must be considered with caution.