On postoperative day 1, elevated interleukin-6 level was associated with postoperative complications, according to a single-center cohort study of patients who had major abdominal surgery.

“Up to 28% of patients undergoing major abdominal surgery experience postoperative complications, including wound infection, sepsis, anastomotic dehiscence, pneumonia,cardiovascular or respiratory events, and mortality” but an accurate means of identifying those in the risk category would contribute the development of prevention stratetgies, the investigators wrote.

Previous studies of cardiothoracic surgery have supported an association of systemic inflammation to poor outcomes. Dr. Thijs Rettig and colleagues at St. Antonius Hospital, Nieuwegein, the Netherlands, sought to clarify if markers of inflammation and major abdominal surgery correlate with outcomes. Their results were published in the July issue of Annals of Surgery.

Researchers conducted a prospective cohort study at a single center using data obtained from the Myocardial Injury and Complications after major abdominal surgery ( MICOLON) study. Participants in the MICOLON study were individuals aged 45 years or older who underwent elective major abdominal surgery. Other inclusion criteria included major cardiovascular (CV) risk factors, coronary artery disease, cerebrovascular accident, diabetes, renal insufficiency, atrial fibrillation, left ventricular dysfunction, aortic valve stenosis, or two minor CV risk factors.

Interleukin-6 (IL-6), tumor necrosis factor (TNF)-alpha, and C-reactive protein (CRP) levels were obtained at baseline and postoperative days 1, 3, and 7 in 137 patients. Systemic inflammatory response syndrome (SIRS) scores were calculated within 48 hours of surgery.

Primary endpoints were 30-day mortality, sepsis, pneumonia, wound infection, anastomotic dehiscence, reoperation, new-onset atrial fibrillation, respiratory insufficiency, congestive heart failure, and myocardial infarction. Data were also collected on length of stay and patients were followed up at 30 days postoperatively for further complications.

With a mean age of 68 years, 59% of patients were male and 30% (n = 40) had an ASA score of 3 or higher. Colorectal (50%), gastroesophageal (22%), and pancreatic (10%) surgery were the most common procedures performed. After excluding 2 patients from analysis for elevated baseline IL-6, 135 patients were analyzed.

At least one postoperative complication was observed in 29% (n = 39) of study subjects with a mean onset of 5 days after surgery. Use of preoperative steroids, aspirin, and statins were not associated with complications; however, blood loss and longer surgery duration where associated with worse outcomes.

In patients with and without complications, differences in IL-6 levels were observed at day 1 at 596 pg/mL vs. 303 pg/mL (P < .01), day 3 at 128 pg/mL vs. 69 pg/mL (P < .01), and day 7 at 76 pg/mL vs. 27 pg/mL (P = .02).

On day 1, CRP was similar in both groups (90 mg/L vs. 78 mg/L; P = .131), but on days 3 (223 mg/L vs. 131 mg/L; P < .001) and 7 (131 mg/L vs. 63 mg/L; P < .001) differences were observed.

Differences in TNF-alpha were observed between groups on day 7 (0.5 pg/mL vs. 0, P < .01). The two groups demonstrated similar leukocyte counts postoperatively.

Prediction for postoperative complications was associated with an IL-6 of 432 pg/mL at day 1, which was 70% specific and 64% sensitive, and had a positive predictive value (PPV) of 44% and negative predictive value (NPV) of 84%. A longer hospital stay of 12 days vs. 7 days (P < .001) was associated with high IL-6 (> 432 pg/mL) vs. a low IL-6 (< 432 pg/mL) at day 1.

Elevated IL-6 level on postoperative day 1 was independently associated with postoperative complications by multivariant regression analysis (AOR: 3.3; 95% confidence interval, 1.3-8.5; P < .02).

The researchers concluded that an increased IL-6 level on postoperative day 1 was associated with increased length of stay and threefold increased risk of complications after major abdominal surgery. They further continued, “It is plausible that early recognition of postoperative complications optimizes the chance of better outcome. One way to enhance early detection of complications is using inflammatory markers as predictors of outcome.”

The authors reported no conflicts of interest.