Viruses are the most common source of
infection among immunocompetent individuals, yet they are not considered a clinically meaningful risk factor among the
critically ill. This work examines the association of
viral infections diagnosed during the
hospital stay or not documented as present on admission to the outcomes of ICU patients with no evidence of immunosuppression on admission. This is a population-based retrospective cohort study of University HealthSystem Consortium (UHC) academic centers in the U.S. from the years 2006 to 2009. The UHC is an alliance of over 90% of the non-profit academic medical centers in the U.S. A total of 209,695
critically ill patients were used in this analysis. Eight hospital complications were examined. Patients were grouped into four cohorts: absence of
infection, bacterial infection only,
viral infection only, and bacterial and
viral infection during same hospital admission.
Viral infections diagnosed during hospitalization significantly increased the risk of all complications. There was also a seasonal pattern for
viral infections. Specific viruses associated with poor outcomes included
influenza, RSV, CMV, and HSV. Patients who had both viral and
bacterial infections during the same hospitalization had the greatest risk of mortality RR 6.58, 95% CI (5.47, 7.91); multi-organ failure RR 8.25, 95% CI (7.50, 9.07); and
septic shock RR 271.2, 95% CI (188.0, 391.3).
Viral infections may play a significant yet unrecognized role in the outcomes of ICU patients. They may serve as
biological markers or play an active role in the development of certain adverse complications by interacting with coincident
bacterial infection.