Severity-of-illness markers as predictors of nosocomial infection in adult intensive care unit patients.

Background: Patients admitted to intensive care units (ICUs) are at high risk for acquiring nosocomial infections. We examined the association between markers of severity of illness at ICU admission and the development of ICU-attributable nosocomial infections.

Methods: Retrospective cohort study of 851 patients admitted to the medical or surgical ICU in an urban teaching hospital from January 1997 to January 1998. Logistic regression analysis was used to identify predictors of nosocomial infection, including the Acute Physiology, Age, Chronic Health Evaluation III severity-of-illness scoring system.

Results: Patients receiving mechanical ventilation on day 1 of ICU admission (OR, 1.99; 95% CI, 1.29-3.06) and patients transferred to the ICU from another unit within the same hospital (OR, 2.04; 95% CI, 1.24-3.34) were twice as likely to acquire an ICU-attributable nosocomial infection compared with patients admitted from other sources. The day-1 Acute Physiology, Age, Chronic Health Evaluation III score was not a significant predictor of nosocomial infection.

Conclusion: The need for mechanical ventilation on ICU day 1 and transfer to the ICU from another unit are independent predictors of ICU-attributable nosocomial infections. Up to 50% of ICU patients who develop nosocomial infections could be easily identified at ICU admission, allowing for targeted use of preventive strategies to reduce the risk of nosocomial infections.