Insulin-dependent diabetics who smoke have higher risk for wound complications

Diabetics who smoke increase the odds of postop wound infection after lumbar surgery.

A prospective, multicenter investigation of posterior lumbar procedure patients has shown that insulin-dependent diabetics have a far greater chance of developing postoperative wound complications than even noninsulin-dependent diabetics who smoke.

The researchers collected data on 18,352 patients from the National Veterans Affairs Medical Center database of more than 1.3 million cases of lumbar procedures performed by neurosurgeons and orthopedic surgeons between 1994 and 2003.

S. Tim Yoon, MD, PhD, of Atlanta, presented the findings at the North American Spine Society annual meeting.

Researchers looked at risk factors for postoperative wound complications, including superficial and deep wound infections and wound dehiscence. They specifically addressed three risk factors: diabetes, both insulin-dependent and noninsulin-dependent; smoking; and the combination of smoking and diabetes.

"We chose all patients who had posterior lumbar procedures who did not have other confounding factors such as infection or cancer," Yoon told Orthopedics Today. "We found that patients with noninsulin-dependent diabetes had close to a threefold increase in risk of infection as compared to the others. Of the three factors we looked at, we believe that insulin-dependent diabetics have, by far, the highest chance for infection, although the other two factors were statistically significant."

He reported that the odds ratio for insulin-dependent diabetics for wound complication following lumbar surgery was 2.8, and between 1.3 and 1.5 for non-insulin dependent diabetics. "Smoking added a modest increase — odds ratio: 1.2 — but it was statistically significant," Yoon said.

A clinical nurse at each of the participating VA hospitals collected the data prospectively, analyzing 52 preoperative, 15 intraoperative and 33 outcome variables. The outcomes were limited to 30 days postsurgery, length of hospitalization or until the patient's death.

Preoperative risk status was categorized into nondiabetic/nonsmoker, noninsulin-dependent diabetic/nonsmoker, noninsulin-dependent diabetic/smoker, insulin-dependent diabetic/nonsmoker, insulin-dependent diabetic/smoker and nondiabetic/smoker.

Of the 18,352 patients in the study, 94.4% were men, 5.6% were women, 6.8% were diabetic, 3.9% were insulin-dependent diabetic and 45.5% were current smokers. Procedures included: lumbar fusions, 12%; laminectomies, 22%; and laminotomies, 65%.

Yoon reported that the overall complication rate was 2.9%, with 1% deep wound infection, 1.6% superficial wound infection and 0.3% wound dehiscence.

The high complication risk for insulin-dependent diabetics in lumbar surgeries is consistent with that seen in other surgeries, Yoon said. "This may be related to poor circulation or even something direct like poor sugar controlm" he said.

He added that surgeons should take great care when operating on patients who have insulin-dependent diabetes and insulin-dependent diabetics who smoke.

For more information:
Yoon ST, The relative importance of diabetes and smoking in postoperative wound complications. Presented at the 21st Annual North American Spine Society Meeting. Sept. 26-30, 2006. Seattle.
S. Tim Yoon, MD, PhD, is an assistant professor of orthopaedic surgery at The Emory Clinic and chief of orthopaedics at V.A. Medical Center, in Atlanta. He can be reached at Emory Orthopaedics & Spine Center, 59 Executive Park South, Atlanta, GA 30329, 404-778-7000.