Risk factors for the development of pneumonia in older adults with burn injury

Abstract

Older adults with burns are at risk for worse outcomes because of factors related to age, comorbidities, and response to treatment. Although the impact of pneumonia has been previously described in burn patients, less is known in the older adult population. In this study, we used the National Burn Repository to characterize patient and injury factors associated with pneumonia development in older adults with burns. We examined the records of all patients in the National Burn Repository aged 55 years and older from 1995 to 2007. To better characterize the effects of age on outcomes, patients were stratified into three categories: 55 to 64 years, 65 to 74 years, and 75 years and older. Pneumonia was identified by listed complications and ICD-9 codes. Comorbidities were classified by Charlson Comorbidity Index Score. Unadjusted and multivariate regression analyses were performed to distinguish the impact of age, comorbidities, and injury factors on pneumonia development and mortality. A total of 23,794 patient records met inclusion criteria during the study period, and 2,052 (8.6%) had pneumonia. Patients who developed pneumonia were more likely to be men (65 vs 56%, P < .001), have higher TBSA (21 vs 13%, P < .001), have sustained inhalation injury (21 vs 7%, P < .001), and have comorbid condition (34 vs 13%, P < .001). On multivariate analysis, factors significantly associated with pneumonia development were male sex, percent TBSA, inhalation injury, and presence of comorbidity. Specifically, chronic lung and heart disease had adjusted odds ratio (OR) of 2.70 and 3.48, respectively, for development of pneumonia (P < .001). By logistic regression, adjusted OR for pneumonia were 0.89 (95% CI 0.74-1.06, P = .18) in the 65 to 74 years age group and 1.26 (95% CI 1.07-1.48, P = .005) in the oldest group compared with the 55 to 64 years age group. Pneumonia during hospitalization was associated with an adjusted OR of 1.91 for death (95% CI 1.61-2.27, P < .001) after controlling for the factors of age, sex, comorbidity, TBSA, and inhalation injury. Injury factors and the presence of comorbidities consistently predicted the development of pneumonia in this large national patient sample. Higher age category also predicted higher pneumonia risk, although this association was only significant in the highest age group. This study, thus, highlights the importance of comorbidities over chronological age in pneumonia development in older adults with burn injuries.