An Observational Veneto Research on Ventilator-Associated Pneumonia (OVeRVAP): attributable mortality and cumulative incidence of ventilator-associated pneumonia

Abstract

Background: The relationship between ventilator-associated pneumonia (VAP) and mortality varies from study to study, and its entity is uncertain due a considerable variation in the attributable mortality. The aim of this study was to evaluate the relationship between VAP frequency and mortality in a cohort of mechanically ventilated patients.

Methods: A multicenter prospective observational study was conducted in 21 Intensive Care Units (ICUs). The patients were recruited from 2008 to 2010 within randomly selected periods. 842 patients of 2595 admitted, met the eligibility criteria and were enrolled in the study. The study's primary outcome was death by any cause in one of the ICUs. We modelled VAP occurrence as a time-dependent covariate and fitted a competing risk analysis model. We estimated the attributable mortality of VAP as the population-attributable fraction of ICU mortality.

Results: A total of 121 patients developed VAP (14.4%), for an incidence rate of 15.7 cases per 1000 ventilator days; of the 175 patients (20.8%) who died during the study period, 31 (25.6%) had VAP. The ICU mortality rate in the patients who developed VAP was 22.6 per 1000 ventilator days (95% CI: 15.9-32.1). We estimated an attributable mortality of 8.4%.

Conclusions: In 8.4% of cases, VAP was the leading cause of death in our study. This indicates that the patients died more frequently with VAP rather than because of it.