The importance of viruses in ventilator-associated pneumonia

Abstract

Abstract Objective: Ventilator-associated pneumonia (VAP) remains a challenge. The importance of viruses in VAP is not established. We sought to determine the prevalence of viruses in VAP and the outcomes of viral VAP. Design: Retrospective study of VAP over 3 years. The frequency of a viral process represented the primary endpoint. Clinical outcomes served as secondary endpoints. We identified variables independently associated with a virus and conducted sensitivity analyses to assess the interaction between type of infection and patient characteristics. Setting: Tertiary-care referral center. Patients: The final cohort consisted of 710 patients and a virus was isolated in 5.1%. Interventions: None. Results: The most common viruses included: rhinovirus, influenza A, and cytomegalovirus. Baseline characteristics were similar between those with and without viral infections. In logistic regression, immunosuppression (adjusted odds ratio [aOR], 2.97; 95% confidence interval [CI], 1.44–6.14) and stem-cell transplantation (SCT, aOR, 3.58; 95% CI, 1.17–10.99) were independently associated with a virus. The presence of either variable performed poorly as a screening test for a virus. In-hospital (22.4% vs 21.6%; P = .869) and 30-day (32.8% vs 27.9%; P = .448) mortality rates were similar between the cohorts, respectively. Sensitivity analyses restricted to patients without a mixed viral and bacterial infection or those who were immunocompetent yielded similar results. Conclusion: Although infrequent, a range of viruses may cause VAP. Viruses more often complicate SCT and immunosuppression, but one can isolate viruses in immunocompetent subjects. Viral VAP produces severe infection and results in high mortality rates. Clinical features do not differentiate viral from nonviral VAP.