Risk Factors for the Development of Early Onset Pneumonia in Adult Trauma Patients
Pneumonia is the most common pulmonary complication seen in trauma patients. Studies of late onset pneumonia (LOP), which occurs more than four days after hospital admission, have been conducted in trauma patients but few studies have focused on risk factors for early onset pneumonia (EOP) which occurs within the first four days of hospital admission. This study sought to identify unique risk factors for EOP in adult trauma patients. A matched case-control study was conducted using subjects identified from the UCSD Medical Center Trauma Registry. Cases with EOP were matched on extent of head injury and date of admission (±6 months), in a one-to-three ratio where possible, to controls without pneumonia. Data were abstracted from the Trauma Registry and subject medical records, and conditional logistic regression used to identify significant risk factors. A second analysis was conducted with LOP cases and controls. The results of this analysis were compared to those of the EOP analysis to determine unique risk factors for EOP. Variables significant in both analyses were likely to be risk factors for pneumonia in general. Misclassified subjects were identified and further analyses conducted with misclassified subjects removed. After misclassified subjects were removed 80 EOP cases and 87 LOP cases were matched to 166 and 182 controls respectively. When head trauma was controlled for by matching, aspiration (OR 4.34, 95% CI 1.47 to 12.75), intubation in the field (OR 6.78, 95% CI 1.529 to 28.86), use of paralytic drugs (OR 3.67, 95% CI 1.20 to 11.24), and enteral feeding (OR 7.38, 95% CI 2.22 to 22.57), were identified as risks factors for the development of EOP when Glasgow Coma Score and intubation were controlled. In comparing EOP and LOP analysis results, it appears that intubation in the field is a unique risk factor for EOP. The risks identified in this study may be modified by carefully evaluating the need for intubation in the field, increased vigilance for aspiration, and limiting the duration of paralysis and enteral feeding.