A new meta-analysis from Brown University has found evidence that vancomycin may not prevent surgical site infections (SSIs) after spine surgery as effectively as some surgeons expect. The Brown University meta-analysis appears in the December 1, 2024 edition of Clinical Orthopaedics and Related Research: under the title: “Does the Application of Topical Vancomycin Reduce Surgical Site Infections in Spine Surgery? A Meta-analysis of Randomized Controlled Trials.”
This study collected data from and analyzed six randomized controlled trials with 2,140 patients (1,053 in the vancomycin group and 1087 in the control group).
According to study co-author, Alan H. Daniels M.D., chief of the Division of Spine Surgery at Warren Alpert Medical School of Brown University, “The meta-analysis found no significant difference in the risk of overall SSIs (3.0% vs. 3.9%), deep SSIs (1.8% vs. 2.7%), or superficial SSIs (1.0% vs. 1.4%) between the vancomycin and control groups.”
“Sub-analyses by instrumented and non-instrumented procedures also showed no differences. These findings do not prove that vancomycin is effective. Rather, our current data from randomized controlled trials has yet to definitively prove its effectiveness.”
Is This a Head Fake?
OTW asked Dr. Daniels to describe the genesis of this study and explain why the randomized controlled trials he examined seem to challenge the efficacy of topical vancomycin in preventing SSIs after spine surgery. He said, “Disagreements likely stem from variations in study design, such as differences in dosing (0.5 mg to 2 mg), placement location (wound bed vs. disc space), and surgical procedures (instrumented vs. non-instrumented, deformity vs microdiscectomy, anterior vs posterior, etc.).”
“Furthermore, heterogeneity in patient populations, definitions of SSIs, and follow-up durations contributes to the conflicting results. The lack of standardization and variability in trial quality also play a role, with some randomized controlled trials lacking robust blinding and allocation concealment methods.”
Dr. Daniels and his research colleagues utilize topical vancomycin in their current spine surgery practice and believe that a comprehensive infection prevention program including topical antibiotics in the wound bed decreased infection rates after spine surgery.
“This study should not convince surgeons not to use topical antibiotics,” said Dr. Daniels and his co-authors, “rather it should encourage a holistic approach to preoperative optimization, optimal sterility and efficiency in surgery, and careful postoperative protocols to reduce infection rates. Future studies are needed to prove the effectiveness of topical vancomycin in preventing postoperative spine infections. These studies should have standardized dosing and methods, yet showing efficacy is difficult because as a specialty we have greatly lowered postoperative infection rates via comprehensive infection prevention programs.”
Regarding any challenges/milestones in setting up the study, Dr. Daniels said, “The meta-analysis faced limitations in identifying smaller differences due to a lack of power for minor effect sizes (below 1.5%). The heterogeneity of included studies (e.g., differences in patient populations, vancomycin dosages, and follow-up times) and the inability to assess publication bias due to the small number of included trials were key obstacles.”
“Although we were excited to successfully limit the analysis to randomized controlled trials, thus reducing bias associated with retrospective and observational studies, this methodology failed to show effect of topical vancomycin in spine surgery which is not a believable result to most spine surgeons. The use of the Cochrane Risk of Bias tool to assess trial quality and the calculation of fragility indices strengthened the analysis.”
