Predictors of Surgical Site Infections Among Patients With Diabetes Mellitus Post Coronary Artery Bypass Graft Surgery

A Quasi-Experimental Study

Audai A. Hayajneh, PhD, RN, CPT; Issa M. Hweidi, RN, MSN, DNSc; Ala M. Zytoon, RN, MSN


Wounds. 2020;32(9):237-243. 

In This Article

Abstract and Introduction


Background: Surgical site infections (SSIs) are considered to be some of the most serious postoperative health concerns among patients with diabetes mellitus (DM) who undergo coronary artery bypass graft (CABG) surgery.

Objective: The purpose of this study is to identify and explore the predictors of SSIs among patients with DM after CABG surgery.

Methods: A quasi-experimental study was conducted using a convenience sample of 144 adult patients who were scheduled to undergo CABG at the main referral heart institute in Amman, Jordan from September 1, 2018, through November 30, 2018. Eligibility criteria stipulated participants should be adult (43–74 years) Jordanian patients with DM who underwent CABG surgery with or without cardiopulmonary bypass (CPB) and elective or urgent CABG surgery as well as being able to read and write Arabic. Key patient demographics, health history, baseline lab work, surgical characteristics, and clinical outcomes were collected from medical records. Data were collected to spreadsheets, anonymized, and entered into statistical software for bivariate and multivariate negative binomial regression analyses. Mean and standard deviation were used to describe continuous variables, and frequencies and percentages were used to describe categorically measured variables, along with chi-squared calculations.

Results: Of the 144 participants, the majority of the patients (130; 90.3%) were male (mean age, 59.66 years [SD = 9.3]). Data revealed the most significant predictors for the development of SSIs post-CABG surgery included higher body mass index (bivariate mean 32 ± 4.6, P = .028; multivariate: [1–1.186] x 100 = 18.6% times more likely to experience SSI), lower preoperative serum cholesterol level (bivariate: P = .005; multivariate: [1–0.973] x 100 = 2.7% times less likely), and higher preoperative serum blood urea nitrogen level (bivariate: P = .011; multivariate: [1-1.191] x 100 = 19.1% times more likely).

Conclusions: Three key factors were found to predict the occurrence of SSIs in patients with DM undergoing CABG. These findings underscore the necessity for health care providers to adhere to and employ meticulous infection control practices when managing at-risk CABG patients.


Surgical site infection (SSI) is defined as an infection that arises after a surgical procedure. It may only affect the superficial layers of an incision or may extend into deeper tissues that were handled during the operation.[1] Surgical site infections are considered one of the most serious postoperative health concerns among patients undergoing cardiac surgery; these infections are accompanied by increased health care costs, rates of readmission, length of hospital stay (LOS), and considerable morbidity and mortality.[2–8] A 2011 study conducted in Jordan[2] showed SSI incidence was 16.8% postoperatively among patients undergoing coronary artery bypass grafting (CABG) surgery. A report issued in 2017 by the Jordanian Royal Medical Services[9] (JRMS) indicated that the rate of SSIs was 6.8% postoperatively among patients undergoing CABG surgery. Increased health costs and high rates of morbidity and mortality are associated with sternal wound infections (SWIs). Most SWIs are classified as superficial. In SWIs, wound debridement and antibiotics are less effective. The postoperative incidence of superficial SWIs among patients undergoing cardiac surgery was approximately 3.3% to 4.65%[10,11] and the mortality rate was 4.6%.[10]

Hyperglycemia occurs when the blood glucose level is >140 mg/dL in patients with or without diabetes mellitus (DM)[12] and is a common occurrence in patients undergoing CABG. About 93% of patients with and 83% of patients without diabetes who underwent CABG had hyperglycemia.[13] Several studies addressing the effects of hyperglycemia during the preoperative, intraoperative, or postoperative period indicated the incidence of higher postoperative infections, particularly SSIs, longer intensive care unit (ICU) and hospital stays, and higher morbidity and mortality after CABG surgery.[14–19]

Diabetes mellitus is regarded as an independent risk factor of SSIs among patients undergoing cardiac surgery and can worsen the condition of these patients postoperatively.[10,11,20–24] The literature shows a significant correlation between uncontrolled glycemic level and adverse health outcomes.[25–27] Glycemic control for patients with DM undergoing cardiac surgery is the main focus for improving clinical outcomes, including infectious complications. Several studies have demonstrated positive outcomes with the use of insulin infusion as a standard of care to prevent potential complications of DM.[28–30]

Numerous studies have revealed that hyperglycemia during the perioperative period, including preoperative, intraoperative, and postoperative phases, is one of the major predictors of adverse health outcomes, such as SSIs, among patients;[14–19] additional variables that have been shown to be predictors of SWIs include obesity, female sex, having bilateral internal mammary artery grafts, and the need for blood products, such as packed red blood cells and platelets.[21]

Infection assessment and prevention is a vital part of the role of health care providers, such as physicians and nurses who manage patients with DM following CABG surgery. The purpose of this study was to identify the predictors of SSIs among patients with DM after CABG surgery.