Perioperative cardiovascular risk stratification of patients with diabetes who undergo elective major vascular surgery

Background: The importance of diabetes mellitus (DM) as an independent risk factor for perioperative cardiac morbidity after vascular surgery is controversial. This study examined the impact of DM on perioperative outcomes and length of stay in patients who underwent major vascular surgery. Methods: Patients who underwent elective aortic reconstruction (n=2792), lower extremity bypass (n=3838), carotid endarterectomy (n=5522), and major amputation (n=3883) from 1997 to 1999 were identified in the National Surgical Quality Improvement Program database of the Department of Veterans Affairs. Outcomes assessed were death, cardiovascular complications (myocardial infarction, stroke, need for cardiopulmonary resuscitation), and length of stay. Multivariable logistic and linear regression models were used to control for patient demographics, procedure type, comorbidities, and diabetic complications. Results: Before adjustment for potential confounders, patients with diabetes had a higher incidence rate of perioperative death (3.9% versus 2.6%; P=.001) and cardiovascular complications (3.3% versus 2.6%; P=.01) when compared with patients without diabetes. After controlling for comorbid conditions, procedure type, and diabetic complications, only patients with DM who underwent treatment with insulin were at statistically increased risk for cardiovascular complications (odds ratio [OR], 1.48; 95% CI, 1.15 to 1.91). Neither DM treated with insulin (OR, 1.10; 95% CI, 0.85 to 1.41) nor DM treated with oral medications (OR, 0.96; 95% CI, 0.73-1.28) was an independent risk factor for death. Important independent risk factors for death included several conditions that are commonly associated with diabetes, including proteinuria, elevated creatinine level, history of congestive heart failure, and history of cerebrovascular accident. DM was also found to increase length of stay by as much as 38% even after adjustment for comorbidities. Conclusion: Patients with diabetes have a higher incidence rate of death and cardiovascular complications. However, after controlling for specific comorbid conditions, the only independent association was between patients with insulin treatment and the risk of cardiovascular complications. DM does not appear to be an independent risk factor for postoperative mortality. All patients with diabetes, regardless of insulin use, have a prolonged length of stay after major vascular surgery.