Clinical question: How does timing of surgical antibiotic prophylaxis affect risk of postoperative surgical-site infections (SSIs)?
Background: Antibiotic prophylaxis for major surgical procedures has been proven in clinical trials to reduce rates of SSI. The Centers for Medicare & Medicaid Services’ (CMS) Surgical Care Improvement Project (SCIP) has implemented quality metrics to ensure antibiotics are administered within 60 minutes of incision; however, studies have failed to show that a 60-minute pre-incision window is advantageous.
Study design: Retrospective cohort.
Setting: Veterans Affairs hospitals.
Synopsis: Using SCIP and VA Surgical Quality Improvement Program data from 112 VA hospitals, 32,459 cases of hip or knee arthroplasty, colorectal surgery, arterial vascular surgery, and hysterectomy from 2005 to 2009 were reviewed. A post-operative SSI occurred in 1,497 cases (4.6%). Using several statistical methods, the relationship between timing of prophylactic antibiotic administration and postoperative SSI within 30 days was evaluated.
In unadjusted models, higher SSI rates were observed with antibiotic administration more than 60 minutes prior to incision (OR 1.34, 95% CI 1.08-1.66) but not after incision (OR 1.26, 95% CI 0.92-1.72), compared with procedures with antibiotics administered within 60 minutes pre-incision. However, after adjustment for patient, procedure, and antibiotic variables, no significant relationship between timing and SSI was observed (P=0.50 for all specialties).
The study sample was comprised primarily of older men and did not include patients who underwent cardiac procedures, limiting the generalizability of the findings. Nonetheless, the study is the largest of its kind and confirms previous studies that suggest there is no significant relationship between timing of antibiotics and SSI. Prophylactic antibiotics should still be used when indicated; however, using timing of prophylactic antibiotics as a quality measure is unlikely to improve outcomes.
Bottom line: Adherence to the empiric 60-minute window metric for timing of prophylactic antibiotics is not significantly associated with risk of SSI.
Citation: Hawn MT, Richman JS, Vick CC, et al. Timing of surgical antibiotic prophylaxis and the risk of surgical site infection. JAMA Surg. 2013 March 20:1-8. doi: 10.1001/jamasurg.2013.134 [Epub ahead of print].