Purpose: To develop a scoring system for stratifying patients in intensive care units (ICUs) by risk of developing nosocomial pneumonia (NP) and to identify the time period associated with the highest risk.
Patients and methods: Two hundred and three patients 18 years of age or older and residing in the ICU for 72 hours or more were followed until development of NP or death or for 48 hours after discharge from the ICU. After the identification of independent risk factors for NP, a scoring system was developed to arrive at a predictive risk index for NP.
Results: Twenty-six (12.8%) patients developed NP. The presence of a nasogastric (NG) tube [odds ratio (OR) = 6.48, 95% confidence intervals (CI) = 2.11 to 19.82], upper abdominal/thoracic surgery (OR = 4.34, 95% CI = 1.43 to 13.14), and bronchoscopy (OR = 2.95, 95% CI = 1.02 to 8.52), most commonly performed for respiratory toilet, were identified as independent risk factors on multivariate analysis. The risks associated with endotracheal intubation and altered consciousness, although not independently significant, were highest when these factors were present for 1 to 4 days after the 72 hours required for study entry (endotracheal intubation, OR = 2.2 to 2.5; altered consciousness, OR = 1.4 to 2.0). The risk then declined; ORs of less than 1 were observed at 7 days. The risk associated with the NG tube was highest during the first 6 days (OR = 6.0 to 19.5). Although a subsequent decrease in risk was observed, the OR was still greater than 2 at 7 days. To obtain a predictive risk index for NP, a scoring system was developed using a multivariate model. This system has a sensitivity of 85% and a specificity of 66% in predicting NP in this ICU population.
Conclusion: ICU patients can be stratified into high- and low-risk groups for NP using a bedside scoring system. Endotracheal intubation, altered mental status, and NG tube are associated with the highest risk of NP during the first 1 to 6 days of their presence after 72 hours of stay in the ICU. After this time period, the risk associated with these factors decreases. Bronchoscopy may be an independent risk factor for NP that has not been previously recognized. This procedure, often done in the ICU for respiratory toilet, may be an avoidable risk in this group of patients.