Association Between Hemoglobin A1c and Surgical Morbidity in Elective Foot and Ankle Surgery

The current guidelines for the management of diabetes in adults have recommended strict glycemic control, with a target hemoglobin A1c of 7.0%. Increasing evidence has shown that strict glycemic control decreases the risk of developing the organ system complications associated with diabetes. Elevated hemoglobin A1c levels have been theorized as a risk factor for complications after elective foot and ankle surgery. To test this hypothesis, we reviewed the Department of Veterans Affairs national administrative and clinical databases for a 6-year period (January 2008 to December 2013). During this period, 21,854 diabetic patients had a recorded hemoglobin A1c measurement within 1 year before undergoing elective foot and ankle surgery. We then identified those patients who had experienced postoperative complications within 30 days of elective foot or ankle surgery using the International Classification of Diseases, ninth revision, codes. The complications were classified into 4 groups: infection, wound healing, mechanical failure, and cardiovascular/pulmonary. The overall 30-day postoperative complication rate was 3.2%. The most common complication was infection (42.3%), followed by mechanical failure (33.4%), cardiovascular/pulmonary (18.4%), and wound healing (5.8%). The average hemoglobin A1c of a patient who had experienced a complication was 6.29% compared with 6.11% for a patient who had not experienced 1 of the 4 complications (p < .001). Logistic regression analysis revealed that for each 1% increase in hemoglobin A1c, the odds of developing a complication increased by 5%. More significant was the 1.78 times increased risk of developing a complication for patients with neuropathy (95% confidence interval 1.45 to 2.20; p = .0001). Even more notable was the associated risk of complications after elective foot and ankle surgery for those patients with comorbid conditions. Patients demonstrated 3.08 times the risk of developing a complication when the patient had 2 to 3 identified comorbid conditions associated with diabetes mellitus (95% confidence interval 2.42 to 3.92; p = .0001). The present retrospective observational investigation has demonstrated glycemic control influences the postoperative complication rates in elective foot and ankle surgery. However, the data collected from the present study have also demonstrated that the complication rates are multifactorial. Comorbid conditions and the presence of peripheral neuropathy also play a significant role in determining a patient's risk of complications after elective foot and ankle surgery.