Selective Decontamination of the Digestive Tract showed no mortality benefit over standard care in mechanically ventilated patients.

This randomized trial enrolled 20,000 patients, of whom 9,289 were randomized and 10,711 underwent ecologic assessment. The study setting comprised 26 ICUs located in Australia and Canada. The population consisted of critically ill patients undergoing mechanical ventilation. The intervention was Selective Decontamination of the Digestive Tract (SDD), which involves the administration of oral antimicrobial and gastric antimicrobial agents. The comparator was standard care. The primary outcome was in-hospital death from any cause at 90 days. The follow-up period was 90 days.

The primary outcome results indicated that SDD did not result in a lower incidence of in-hospital death from any cause at 90 days compared with standard care. Specifically, 1,175 of 4,215 patients (27.9%) in the SDD group died, whereas 1,494 of 5,065 patients (29.5%) in the standard-care group died. The odds ratio was 0.94 with a 95% confidence interval of 0.84 to 1.05 and a P value of 0.27. This indicates no statistically significant difference between the groups regarding the primary endpoint.

Key secondary outcomes demonstrated specific benefits for the SDD group. New bloodstream infections were lower in the SDD group, with an adjusted mean difference of -1.30 percentage points. Absolute numbers showed a rate of 4.9% in the SDD group versus 6.8% in the standard-care group, with a 95% CI of -2.55 to -0.05. Additionally, the number of antibiotic-resistant organisms cultured was lower in the SDD group, showing an adjusted mean difference of -9.60 percentage points. Absolute numbers were 16.8% in the SDD group versus 26.8% in the standard-care group, with a 95% CI of -12.40 to -6.80.

Safety and tolerability findings were reported for the study period. Adverse events were reported in 12 patients (0.3%) in the SDD group and in no patients in the standard-care group. Serious adverse events occurred in 47 patients (1.1%) in the SDD group and 59 patients (1.2%) in the standard-care group. Discontinuations were not reported, and tolerability was not reported. The study noted that noninferiority of SDD was not confirmed for the development of new antibiotic-resistant organisms in the ecologic assessment component.

Methodological limitations include the fact that noninferiority of SDD was not confirmed for the development of new antibiotic-resistant organisms in the ecologic assessment. The study design was a randomized trial, but the study phase and publication type were not reported. Funding was provided by the National Health and Medical Research Council of Australia and the Canadian Institutes of Health Research. The study does not establish causality, and surrogate outcomes may not fully reflect clinical benefit. The ecologic assessment component did not confirm noninferiority for new antibiotic-resistant organisms.

Clinical implications suggest that SDD did not result in a lower incidence of in-hospital death than standard care among critically ill patients undergoing mechanical ventilation. While SDD reduced the incidence of new bloodstream infections and cultured antibiotic-resistant organisms, the lack of mortality benefit questions its routine adoption. Questions remain unanswered regarding the long-term impact of SDD on patient outcomes and the balance between infection reduction and potential adverse events. The study highlights the need for further research to clarify the role of SDD in improving survival rates.

Key takeaway: Consider SDD's lack of mortality benefit despite reduced infections in ventilated patients.