Antibiotic Duration May NOT Alter Surgical Infection Risk?

New research from Mount Sinai in New York has come up with some revealing issues regarding antibiotic prophylaxis. The work, unpublished as of yet, is titled, “Characteristics of Antibiotic Prophylaxis and Risk of Surgical Site Infections in Primary Total Hip and Knee Arthroplasty.”

Jashvant Poeran, M.D., Ph.D., assistant professor of Population Health Science and Policy, Medicine and Orthopedics at the Icahn School of Medicine at Mount Sinai and co-author explained the genesis of his study to OTW, “Infections are a serious complication, but, fortunately, very rare after hip and knee arthroplasty. This means that for comparative effectiveness studies, i.e., comparing effectiveness of various antibiotic prophylaxis strategies in terms of infection risk, large sample sizes are needed which are generally not attainable for randomized controlled trials.”

“This is a great example of a clinical question which is not likely to be answered with a randomized controlled trial, given that infections after hip and knee replacement surgery are devastating, but rare. Also, trials do not provide information on the penetration of guideline recommendations into daily clinical practice.”

“In this nationwide study of 1.3 million lower extremity joint arthroplasties, we found that most patients (72.2%) received cefazolin for prophylaxis, the most commonly recommended prophylactic antibiotic. However, the percentage of cases in which vancomycin is added to cefazolin as combined prophylaxis is increasing (2.9% in 2006 vs. 8.1% in 2016).”

“Theoretically, selection for a prophylactic antibiotic is based on patient-related factors such as MRSA colonization. However, while we did not have information on such clinical details, we did find that prophylaxis selection was largely based on hospital factors (and not the available patient characteristics) which suggests that the choice for prophylactic antibiotic may be more dependent on factors such as local protocols, antibiograms or antibiotic stewardship programs.”

“We also found that in around half of patients, antibiotic prophylaxis appeared to be continued beyond the day of surgery, not in line with most antibiotic prophylaxis guidelines. Importantly: Relative to cefazolin, particularly significantly higher odds for infections were seen when vancomycin was used as the sole prophylactic: +36% and +29% increased odds of infection when compared to patients receiving just cefazolin.”

“Interestingly, prophylaxis duration (use on or beyond the day of surgery) did not alter SSI [surgical site infection] risk; this justifies a more detailed look at the observed non-selective use of prolonged prophylaxis.”

“Importantly: in using observational data there is the always present risk of confounding. Therefore, we applied several sensitivity analyses to determine if our findings persisted in alternative analyses, which they did. This demonstrates the robustness of our findings.”

“This study suggests that it may be helpful in engaging with local antibiotic stewardship teams if there are any concerns regarding infection rates; this will facilitate the discussion on what is behind the current local prophylaxis guidelines and if these need to be adjusted. Caution may be necessary if vancomycin is selected as the sole prophylactic antibiotic, for example in cases of allergies to cephalosporins.”

“One of the crucial follow-up questions regards the effectiveness of non-selective prolonged antibiotic prophylaxis. Should this be reserved only for patients perceived at high risk for infections? And how should these patients be identified? Based on comorbidities such as diabetes mellitus, obesity or others?”