Descriptive Epidemiology and Attributable Morbidity of Ventilator-Associated Events

Abstract

Objective.The Centers for Disease Control and Prevention implemented new surveillance definitions for ventilator-associated events (VAEs) in January 2013. We describe the epidemiology, attributable morbidity, and attributable mortality of VAEs.Design.Retrospective cohort study.Setting.Academic tertiary care center.Patients.All patients initiated on mechanical ventilation between January 1, 2006, and December 31, 2011.Methods.We calculated and compared VAE hazard ratios, antibiotic exposures, microbiology, attributable morbidity, and attributable mortality for all VAE tiers.Results.Among 20,356 episodes of mechanical ventilation, there were 1,141 (5.6%) ventilator-associated condition (VAC) events, 431 (2.1%) infection-related ventilator-associated complications (IVACs), 139 (0.7%) possible pneumonias, and 127 (0.6%) probable pneumonias. VAC hazard rates were highest in medical, surgical, and thoracic units and lowest in cardiac and neuroscience units. The median number of days to VAC onset was 6 (interquartile range, 4–11). The proportion of IVACs to VACs ranged from 29% in medical units to 42% in surgical units. Patients with probable pneumonia were more likely to be prescribed nafcillin, ceftazidime, and fluroquinolones compared with patients with possible pneumonia or IVAC-alone. The most frequendy isolated organisms were Staphylococcus aureus (29%), Pseudomonas aeruginosa (14%), and Enterobacter species (7.9%). Compared with matched controls, VAEs were associated with more days to extubation (relative rate, 3.12 [95% confidence interval (CI), 2.96–3.29]), more days to hospital discharge (relative rate, 1.46 [95% CI, 1.37–1.55]), and higher hospital mortality risk (odds ratio, 1.98 [95% CI, 1.60–2.44]).Conclusions.VAEs are common and morbid. Prevention strategies targeting VAEs are needed.