Nine RCTs (2,277 patients) were included in the analysis.
Compared to usual care, subglottic drainage of secretions reduced the risk of ventilator associated pneumonia by 48% (RR 0.52, 95% CI 0.42 to 0.65; nine RCTs). There were no significant differences between groups for intensive care unit mortality (four RCTs) or for hospital mortality (four RCTs).
Subglottic drainage did not significantly reduce the number of days on mechanical ventilation (WMD -1.04 days, 95% CI -2.79 to 0.71; six RCTs). Although subgroup analyses including only patients thought to require mechanical ventilation for at least 48 hours reported a significant reduction in number of days on mechanical ventilation (WMD 2.0 days, 95% CI 1.6 to 2.3 days); the number of RCTs for this analysis was not reported.
Increased time to ventilator associated pneumonia was reported for subglottic drainage compared to usual care (WMD 2.89, 95% CI 0.09 to 5.69; eight RCTs).
Significant statistical heterogeneity was found for the number of days on mechanical ventilation and time to ventilator associated pneumonia (data not reported).