Surgical Prophylactic Antibiotic: Timing Doesn't Alter Risk

Lara C. Pullen, PhD

March 21, 2013

A study published online March 20 in JAMA Surgery finds no evidence that prophylactic antibiotics must be administered within the 60 minutes before surgery. The study found that the risk for surgical site infection (SSI) is not significantly associated with prophylactic antibiotic timing. SSI risk does vary, however, by patient, procedure, and antibiotic properties.

Mary T. Hawn, MD, MPH, from Birmingham Veterans Administration Hospital, Alabama, and colleagues describe in their work as "tshe largest study to date to evaluate the relationship between prophylactic antibiotic timing and subsequent SSI for major surgical procedures and the only study to assess timing as a continuous variable."

They conclude, "We did not observe a significant relationship between timing and SSI in this contemporary national VA SCIP [Veterans Affairs Surgical Care Improvement Project) cohort, but we did observe a significant association between choice of antibiotic and SSI for orthopedic and colorectal procedures."

The study tested the recommendation that prophylactic antibiotics be administered 60 minutes before surgery. Previous studies have shown that other administration times may be more effective than the recommended 60 minutes.

The analysis measured timing as a continuous variable, included detailed patient- and procedure-level data, and assessed SSI during the first 30 days after surgery. The study included patients, primarily older men, who underwent orthopedic, colorectal, vascular, and gynecologic procedures from 2005 to 2009 in 112 Veterans Affairs hospitals. It excluded cardiac procedures.

The team compared SSI rates in patients who received antibiotics within 60 minutes before incision with rates in patients who received antibiotics more than 60 minutes before incision. The authors found an unadjusted odds ratio of 1.34 (95% confidence interval, 1.08 - 1.66).

However, after adjusting for patient, procedure, and antibiotic variables, the team found no significant association between timing of antibiotic administration and SSI rate.

"This article is not a call to abandon prophylactic antibiotics when indicated, as most studies have shown a significant reduction in postoperative surgical site infections with their use (when compared with no antibiotics) ," writes Leigh Neumayer, MD, MS, from the University of Utah in Salt Lake City, in the accompanying editorial. "However, it does once again strongly suggest that the current publicly reported measures are not associated with improved outcomes. As surgeons, we should work with federal and local agencies to define metrics that are more robustly associated with better outcomes for our patients."

Dr. Hawn and Dr. Neumayer have disclosed no relevant financial relationships.

JAMA Surg. Published online March 20, 2013. Abstract