Refinement Of Survival Prediction In Patients Undergoing Lower Extremity Bypass Surgery: Stratification By Chronic Kidney Disease Classification

Objective: ESRD imparts a significant survival disadvantage to individuals undergoing lower extremity revascularization. We sought to examine the prognostic significance of CKD classification on survival rates in lower extremity bypass patients.
Methods: Evaluation of a prospective registry for consecutive patients undergoing first-time, lower extremity vein bypass surgery. GFR was estimated using the Modification of Diet in Renal Disease equation using each patient's preoperative creatinine. CKD categories were taken from current National Kidney Foundation Kidney Disease Outcomes Quality Initiative staging criteria.
Results: There were 458 subjects with a mean age 68.1±10.8 (mean±S.D.). Of the entire population (Table), there were 274(60%) males, 378(82.5%) Caucasian, 270(59.0%) diabetics, 333(72.7%) had hypertension, 242(52.8%) had coronary artery disease, and 205(44.8%) had dyslipidemia. The indication was critical ischemia in 384(83.8%) subjects. Among the variables examined, diabetes and critical ischemia as the indication for bypass were significantly skewed toward higher CKD classifications, p<.001. 5-year survival rates by CKD class were: CKD 1/2 57%, CKD 3 46%, CKD 4 23%, and CKD 5 9.5% (Figure). On univariate analysis, age(p < .0001), CAD(p=.001), DM(p=.02), hypertension(p=.02), critical ischemia(p=.0007), and CKD(p<.0001) were significant predictors of survival; however in a cox proportional hazard model, only age(p<.0001) and CKD(p<.0001) retained significance. Subjects within the CKD 5 classification were more likely to have a major amputation, (p=.018), when compared to all other CKD classes.
Conclusions: CKD staging adequately differentiates survival curves among patients with renal impairment who are undergoing lower extremity bypass surgery. This may help in clinical decision analysis as well as refinement of stratification in future clinical trial design where survival is an endpoint.