Predictors of in-hospital mortality and 6-month functional outcomes in older adults after moderate to severe traumatic brain injury

Abstract

Introduction

Traumatic brain injury (TBI) is the single largest cause of death and disability following injury worldwide. While TBI in older adults is less common, it still contributes to significant morbidity and mortality in this group. Understanding the patient characteristics that result in good and poor outcome after TBI is important in the clinical management and prognosis of older adult TBI patients. This population-based study investigated predictors of mortality and longer term functional outcomes following serious TBI in older adults.

Methods

All older adults (aged > 64 years), isolated moderate to severe TBI cases from the population-based Victorian State Trauma Registry for the period July 2005 to June 2007 (inclusive) were extracted for analysis. Demographic, injury event, injury diagnosis, management and comorbid status information were obtained and the outcomes of interest were in-hospital mortality, and the Glasgow Outcome Scale-Extended (GOS-E) score at 6 months post-injury. Multivariate logistic regression analyses were used to identify independent predictors of in-hospital mortality and independent living (GOS-E > 4) status at 6 months.

Results

Of the 428 isolated, older adult TBI cases, the majority were the result of a fall (88%), male (55%), and aged > 74 years (76%). The in-hospital death rate was 28% and increasing age (p = 0.009), decreasing GCS (p < 0.001) and injury type (p = 0.002) were significant independent predictors of in-hospital mortality. Of the 310 patients who survived to discharge, 65% were successfully followed-up 6 months following injury. There was no difference between patients lost to follow-up and those successfully followed-up with respect to the key population indicators of age, gender, or head injury severity. Younger (<75 years) patients, and those with an SBP on arrival at hospital of 131–150 mmHg, were at increased odds of living independently at follow-up. No patients with a GCS < 9 had a good 6-month outcome, and most of them died. The survival rate for brainstem injury was also low (21%).

Conclusion

In this population-based study, we found that age, GCS, brainstem injury, and systolic blood pressure were the most important factors in predicting outcome in older adults with an isolated moderate to severe TBI.

Introduction

Traumatic brain injury (TBI) is the single largest cause of death and disability following injury worldwide, and is estimated to affect over 1.4 million individuals a year in the United States alone.¹³ Of those, 90,000 people experience permanent disability post-injury and approximately 50,000 people die.¹³ In the older adult population (age ≥ 65 year) 155,000 people suffer a TBI each year, of which more than 12,000 die.¹³ A recent Australian study reported 22,710 TBI-related hospitalisations in Australia between 2004 and 2005, resulting in costs of $184 million.¹¹ Sixty-five percent of TBI-related hospital mortality in this study was in the older adult population.

TBI is known to result in high mortality rates and disability throughout all age groups.2, 9, 12, 14, 19 The most common group of patients suffering a TBI is of young males involved in a high speed motor vehicle collision (MVC).¹⁹ TBI in older adults is less common, however it still contributes to significant morbidity and mortality in this group. The most common cause of TBI in older adults is a fall and previous studies have highlighted worse outcomes in older adults compared to younger TBI patients.10, 23 Older patients have increased mortality and worse functional outcomes compared to younger persons.2, 12, 14, 21 The length of stay and need for rehabilitation is significantly higher in older adult TBI patients, highlighting the high morbidity, resource usage and costs of managing this patient group.¹⁴ Understanding the patient characteristics that result in good and poor outcome after TBI is important in the clinical management and prognosis of older adult TBI patients.

Previous studies of TBI have identified multiple factors predictive of TBI outcome including age,2, 8, 12, 14, 15, 17, 18, 21, 23 sex, head injury severity, discharge destination,⁷ comorbid status,7, 8 the use of therapeutic warfarin,²⁰ minority groups,¹ injury type,9, 17 and systolic blood pressure.3, 16, 22 However, population-based studies of older adults with both short- and long-term outcomes are lacking. This population-based study investigated the predictors of mortality and longer term functional outcomes following moderate to severe TBI in older adults.