Efficacy of Prophylactic Antibiotic Therapy in Spinal Surgery: A Meta-analysis

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Abstract
There is considerable variation in practice regarding the use of prophylactic antibiotic therapy in spinal operations. To date, individual studies have not demonstrated a significant benefit for prophylactic antibiotic therapy in spinal operations. Systematic database searches for randomized prospective trials of prophylactic antibiotic therapy in spinal surgery, general neurosurgery, and orthopedic surgery were performed. Random-effects meta-analysis and Bayesian meta-regressions of treatment benefits versus baseline infection rates and other trial characteristics were performed. Six prospective randomized trials or trial subgroups, enrolling 843 patients, were identified, i.e., one spinal surgery trial, four general neurosurgery trials, and one general orthopedic surgery trial. No individual trial demonstrated a statistically significant effect of prophylactic antibiotic therapy for spinal surgery patients. Raw pooled infection rates were 2.2% (10 of 451 patients) with antibiotics and 5.9% (23 of 392 patients) without antibiotics. Individual trial infection rates ranged from 1.2 to 8.5%. The pooled odds ratio was 0.37 (95% confidence interval, 0.17–0.78), favoring antibiotic treatment (P < 0.01). There was no significant heterogeneity in treatment efficacy among the trials. Bayesian meta-regression was used to test whether antibiotics were less effective in trials with low baseline infection rates and whether an optimal antibiotic regimen could be identified. There was no significant difference in antibiotic treatment effects in trials with lower baseline infection rates, in trials using antibiotics with gram-negative coverage in addition to gram-positive coverage, or in trials using multiple-dose versus single-dose regimens. Nonrandomized studies of antibiotic therapy in spinal surgery yielded greater treatment effect estimates than did randomized trials, but not significantly so. Prophylactic antibiotic therapy is beneficial for spinal surgery, even when expected infection rates without antibiotic treatment are low.