Meta-analysis of randomised controlled trials of selective decontamination of the digestive tract. Selective Decontamination of the Digestive Tract Trialists' Collaborative Group

Abstract

Objective: To determine the clinical benefits of selective decontamination of the digestive tract in patients treated in intensive care units.

Design: Meta-analysis of 22 randomised trials that compared different combinations of oral non-absorbable antibiotics, with or without a systemic component, with no treatment in controls.

Subjects: 4142 patients seen in general and specialised intensive care units around the world. 2047 received some form of antibiotic treatment, the remainder no prophylaxis.

Data analysis: Each trial was reviewed through direct contact with study investigators. Data collected were: the randomisation procedure, number of patients, number excluded from the analysis, and numbers of respiratory tract infections and deaths. Data were combined according to an intention to treat analysis with the Mantel-Haenszel-Peto method.

Main outcome measures: Respiratory tract infections and total mortality.

Results: Selective decontamination of the digestive tract significantly reduced respiratory tract infections (odds ratio 0.37; 95% confidence interval 0.31 to 0.43). The value of the common odds ratio for total mortality (0.90; 0.79 to 1.04) suggested at best a moderate treatment effect, reaching statistical significance only when the subgroup of trials of topical and systemic treatment combined was considered separately (odds ratio 0.80; 0.67 to 0.97). No firm conclusions could be drawn owing to large variations in patient mix and severity within and between trials.

Conclusions: The findings strongly indicate that selective decontamination significantly reduces infection related morbidity in patients receiving intensive care. They also highlight why definite conclusions about the effect of prophylaxis on mortality cannot be drawn despite the large number of trials available. Based on the most favourable results obtained by pooling data from trials in which combined topical and systemic treatment was used it may be estimated that 6 (range 5-9) and 23 (13-139) patients would need to be treated to prevent one respiratory tract infection and one death respectively.