In a randomized trial of 5,982 critically ill patients receiving mechanical ventilation, selective decontamination of the digestive tract (SDD) did not significantly reduce in-hospital mortality within 90 days, compared with standard care, but the confidence interval around the mean effect indicated a clinically important benefit.
In Australia, adults in 19 intensive care units (ICUs) were studied in the cluster, crossover, randomized trial. For 2 alternating 12-month periods with a 3-month gap in between, ICUs were randomly assigned to adopt or not adopt an SDD strategy. The SDD intervention included a 6-hourly application of an oral paste and administration of a gastric suspension containing colistin, tobramycin, and nystatin for the duration of mechanical ventilation, plus a 4-day course of an intravenous antibiotic with a suitable antimicrobial spectrum.
Based on a primary outcome of in-hospital mortality within 90 days, 8 secondary outcomes, and an ecological assessment, the investigators found: “Of 5,982 patients (mean age, 58.3 years; 36.8% women) enrolled from 19 ICUs, all patients completed the trial. There were 753/2,791 (27.0%) and 928/3,191 (29.1%) in-hospital deaths in the SDD and standard care groups, respectively (mean difference, −1.7% [95% CI, −4.8% to 1.3%]; odds ratio, 0.91 [95% CI, 0.82-1.02]; P = .12). Of 8 prespecified secondary outcomes, 6 showed no significant differences. In the SDD vs standard care groups, 23.1% vs 34.6% had new [antibiotic-resistant organisms (AROs)] cultures (absolute difference, −11.0%; 95% CI, −14.7% to −7.3%), 5.6% vs 8.1% had new positive blood cultures (absolute difference, −1.95%; 95% CI, −3.5% to −0.4%), and 0.5% vs 0.9% had new Clostridioides difficile infections (absolute difference, −0.24%; 95% CI, −0.6% to 0.1%). In 8,599 patients enrolled in the ecological assessment, use of SDD was not shown to be noninferior with regard to the change in the proportion of patients who developed new AROs (−3.3% vs −1.59%; mean difference, −1.71% [1-sided 97.5% CI, −∞ to 4.31%] and 0.88% vs 0.55%; mean difference, −0.32% [1-sided 97.5% CI, −∞ to 5.47%]) in the first and second periods, respectively.”
Editorial: “After 40 years of clinical trial experience, important questions regarding the utility of SDD in critically ill patients receiving mechanical ventilation have been answered for settings with a low prevalence of antibiotic resistance,” writes an editorialist. “Yet, large-scale studies are still needed to determine effectiveness in specific patient populations and in settings with a high prevalence of multidrug-resistant pathogens.”