Prophylactic Antibiotics May Improve Outcome in Patients With Severe Burns Requiring Mechanical Ventilation: Propensity Score Analysis of a Japanese Nationwide Database

Background. The use of prophylactic antibiotics for severe burns in general settings remains controversial and is not suggested by recent guidelines owing to lack of evidence for efficacy. We examined the hypothesis that prophylactic systemic antibiotic therapy may reduce mortality in patients with severe burns. Methods. We identified 2893 severe burns patients (burn index ≥10) treated at 583 hospitals between July 2010 and March 2013 using the Japanese diagnosis procedure combination inpatient database. We categorized the patients according to whether they received mechanical ventilation within 2 days after admission (n = 692) or not (n = 2201). We further divided the patients into those with and without prophylactic antibiotics and generated 232 and 526 propensity score–matched pairs, respectively. We evaluated 28-day all-cause in-hospital mortality. Results. Among the mechanically ventilated patients, significant differences in 28-day in-hospital mortality existed between control and prophylaxis groups in both unmatched (control vs prophylaxis; 48.6% vs 38.3%; difference, 10.2%; 95% confidence interval [95% CI], 2.7 to 17.7) and propensity score–matched groups (47.0% vs 36.6%; difference, 10.3%; 95% CI, 1.4 to 19.3). Among patients without mechanical ventilation, there was no significant difference in 28-day in-hospital mortality between the 2 groups in both the unmatched (control vs prophylaxis; 7.0% vs 5.8%; difference, 1.2%; 95% CI, −1.2 to 3.5) and propensity-matched groups (5.1% vs 4.2%; difference, 0.9%; 95% CI, −1.6 to 3.5). Conclusions. Prophylactic antibiotics use may result in improved 28-day in-hospital mortality in mechanically ventilated patients with severe burns but not in those who do not receive mechanical ventilation.