4 Need for Mechanical Ventilation is More Predictive of Mortality than Age, %TBSA, and Frailty Score in Elderly Burn Patients

Abstract

The multifactorial frailty index (FI) has shown to better predict elderly burn outcomes than traditional predictive models that do not incorporate pre-injury physiological condition. Additionally, inhalation injury correlates with worse outcomes. If FI and need for mechanical ventilation serve as independent predictors of adverse outcomes, they can be used as a clinical tool for patient management. A retrospective review was conducted on 114 patients 65 years of age and older admitted with a burn injury >5% total body surface area (TBSA) from March 2010 to March 2017. Data collected included age, gender, %TBSA, inhalation injury, in hospital mortality, 90 day mortality, hospital length of stay, length of mechanical ventilation, number of surgical procedures, insurance status, and discharge disposition. Patient history documentation was used to assess preinjury physiological condition. The Canadian Study of Health and Aging clinical frailty scale was used to determine FI scores. Univariable analysis demonstrated significant mortality associations with mechanical ventilation, %TBSA, FI, and burn with inhalation injury. Multivariable analysis confirmed need for mechanical ventilation, %TBSA, and FI remained hazardous. For every one-unit increase in the index score the risk of death increased by approximately 75% (HR = 1.75, 95% CI: 1.25 - 2.45; p<.001). Similarly, for every % increase in TBSA, the risk of death increased by 5.7% (HR = 1.06, 95% CI: 1.03 - 1.08; p<.001). Lastly, patients who were vented were 6.7 (95% CI: 1.52 - 29.44) times more likely to die (p=.01). Interestingly, surgical interventions were protective (HR = 0.04, 95% CI: 0.01 - 0.33; p=.003). These findings indicate that the most important predictor of mortality in elderly burn patients is the need for mechanical ventilation; FI is more accurate than age at predicting outcomes for mortality; and burn with inhalation injury is associated with a greater mortality risk than burn alone. Additionally, the risk of mortality increases as burn size does, and decreases with one or more surgeries versus no surgeries. FI and need for mechanical ventilation have a significant negative impact on clinical outcomes in elderly burn patients and can aid clinicians in their discussions regarding expected outcomes and goals of care.