Attributable mortality of ventilator-associated pneumonia: a reappraisal using causal analysis

Am J Respir Crit Care Med. 2011 Nov 15;184(10):1133-9. doi: 10.1164/rccm.201105-0867OC.


Rationale: Measuring the attributable mortality of ventilator-associated pneumonia (VAP) is challenging and prone to different forms of bias. Studies addressing this issue have produced variable and controversial results.

Objectives: We estimate the attributable mortality of VAP in a large multicenter cohort using statistical methods from the field of causal inference.

Methods: Patients (n = 4,479) from the longitudinal prospective (1997-2008) French multicenter Outcomerea database were included if they stayed in the intensive care unit (ICU) for at least 2 days and received mechanical ventilation (MV) within 48 hours after ICU admission. A competing risk survival analysis, treating ICU discharge as a competing risk for ICU mortality, was conducted using a marginal structural modeling approach to adjust for time-varying confounding by disease severity.

Measurements and main results: Six hundred eighty-five (15.3%) patients acquired at least one episode of VAP. We estimated that 4.4% (95% confidence interval, 1.6-7.0%) of the deaths in the ICU on Day 30 and 5.9% (95% confidence interval, 2.5-9.1%) on Day 60 are attributable to VAP. With an observed ICU mortality of 23.3% on Day 30 and 25.6% on Day 60, this corresponds to an ICU mortality attributable to VAP of about 1% on Day 30 and 1.5% on Day 60.

Conclusions: Our study on the attributable mortality of VAP is the first that simultaneously accounts for the time of acquiring VAP, informative loss to follow-up after ICU discharge, and the existence of complex feedback relations between VAP and the evolution of disease severity. In contrast to the majority of previous reports, we detected a relatively limited attributable ICU mortality of VAP.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Infective Agents / therapeutic use
  • Causality
  • Cross Infection / mortality
  • Female
  • Humans
  • Intensive Care Units / statistics & numerical data
  • Logistic Models
  • Male
  • Middle Aged
  • Pneumonia, Ventilator-Associated / drug therapy
  • Pneumonia, Ventilator-Associated / etiology
  • Pneumonia, Ventilator-Associated / microbiology
  • Pneumonia, Ventilator-Associated / mortality*
  • Proportional Hazards Models
  • Prospective Studies
  • Risk Assessment
  • Risk Factors
  • Severity of Illness Index
  • Survival Analysis


  • Anti-Infective Agents