Cross-sectional and case-control analyses of the association of kidney function staging with adverse postoperative outcomes in general and vascular surgery.

Objective: This study aimed to assess kidney dysfunction in general surgical patients and examine the effect on postoperative mortality and morbidity.
Background: An estimated 13% of the US population has chronic kidney disease (CKD), but awareness among patients and caregivers is lacking.
Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) data sets for 2005-2007 were analyzed. Preoperative kidney function was assessed by the Modification of Diet in Renal Disease formula for estimated glomerular filtration rate (eGFR) and staged according to National Kidney Foundation. Cross-sectional analyses were performed for 30-day mortality (Cox proportional hazard) and incidence of major complications (nominal logistic regression). A case-control cohort of colectomy cases was analyzed comparing patients in the stage 4 CKD group and the no CKD group (no-CKD).
Results: Sixty-four percent of evaluable patients had reduced eGFR, but eGFR was not evaluable in 28% of the surgical cases. In the 260,352 evaluable cases, adjusted hazard ratio for 30-day mortality was 2.30 [95% confidence interval (CI), 2.11-2.51] for stage 3 CKD; 3.37 (95% CI, 3.01-3.76) for stage 4 CKD; and 3.05 (95% CI, 2.68-3.47) for stage 5 CKD compared with no-CKD (P < 0.0001). CKD was an independent risk factor for having major complications postsurgery [stage 3, odds ratio (OR) = 1.24 (95% CI, 1.19-1.29); stage 4, OR = 1.65 (95% CI, 1.52-1.78); and stage 5 CKD, OR = 1.40 (95% CI, 1.30-1.51); P < 0.0001]. The case-control for colectomy was confirmatory: increased 30-day mortality in stage 4 CKD versus no-CKD (hazard ratio = 2.58, 95% CI, 1.13-5.92; P = 0.025).
Conclusions: Renal insufficiency may be underrecognized in the general and vascular (noncardiac) surgery population, is a leading independent predictor of poor early postoperative outcomes, and should be routinely assessed in the preoperative setting.