Mortality Determinants in Severe Traumatic Brain Injury with Pneumonia: A Retrospective Study

Introduction: Traumatic brain injury (TBI) is defined as an acute brain injury caused by mechanical forces to the head, excluding those related to drugs, alcohol, medications, or other conditions, such as systemic injuries, psychological trauma, or coexisting medical issues. TBI is a global public health issue responsible for significant disability and mortality, with an estimated global incidence of 69 to over 100 million new cases annually. This burden may be higher due to underreporting, particularly in low- and middle-income countries (LMICs). Several methods have been established to classify TBI, one of them is based on its severity with the Glasgow Coma Score (GCS). Pneumonia is a frequent complication in traumatic brain injury (TBI) patients, especially those on prolonged mechanical ventilation. Pneumonia could be classified based on the source of infection into ventilator-associated pneumonia (VAP), hospital-associated pneumonia (HAP), and community-acquired pneumonia (CAP).

Objective: To evaluate the mortality and risk factors of severe traumatic brain injury (sTBI) with pneumonia.

Methods: This study is a cross-sectional study with observational analytical investigations. The sample of this study is sTBI patients who were treated in Dr. Soetomo General Academic Hospital in 2023. Descriptive statistics were used to summarize the patients' characteristics. Chi-square tests and logistic regression were used to find relationship between factors that increase the risk of death and the development of pneumonia.

Results: In 2023, we documented 832 TBI cases, of these, 479 cases (57.6%) were mild TBI, 273 cases (32.8%) were moderate brain injuries, while severe brain injuries (sTBI) with 80 cases (9.6%). Our study shows that 50% of patients with sTBI have pneumonia, and VAP itself is one of the contributing factors to mortality in this population (p<0.001).

Conclusion: Of all types of pneumonia in this study, there is a statistical correlation between mortality and VAP in sTBI patients.

INTRODUCTION

Traumatic brain injury (TBI) is defined as an acute brain injury caused by mechanical forces to the head, excluding those related to drugs, alcohol, medications, or other conditions such as systemic injuries, psychological trauma, or coexisting medical issues (¹). TBI is typically classified by severity (mild, moderate, or severe), mechanism of injury (closed or penetrating), and clinical presentation (focal or diffuse injuries). The severity of a traumatic brain injury is usually measured using the Glasgow Coma Scale (GCS), where a score of 13-15 indicates a mild injury, 9-12 indicates a moderate injury, and 3-8 indicates a severe injury, which can lead to long periods of unconsciousness and a higher risk of death (²).

Closed TBIs, often caused by falls, motor vehicle accidents, or sports injuries, involve nonpenetrating trauma that leads to brain movement within the skull. In contrast, penetrating TBIs, typically from objects breaching the skull, are linked with severe damage and increased mortality. Clinical presentation further divides TBIs into focal injuries, like contusions and hematomas, and diffuse injuries, such as diffuse axonal injury (DAI), which results from rotational forces and carries poor outcomes (²). Understanding these classifications is critical for optimizing treatment and improving patient outcomes.

TBI is a global public health issue responsible for significant disability and mortality, with an estimated global incidence of 69 to over 100 million new cases annually. This burden may be higher due to underreporting, particularly in lowand middle-income countries (LMICs) (³). In LMICs, road traffic accidents (RTAs) account for nearly 60% of all TBIs (⁴), while in high-income countries (HICs), falls especially among the elderly have become the leading cause, followed by motor vehicle accidents and sports-related injuries (⁵). Young males, particularly those aged 15-24, are disproportionately affected by TBIs due to risky behaviors like impaired driving and poor seatbelt use (²,⁶), while the elderly suffer primarily from fall-related TBIs due to factors like osteoporosis and cognitive impairment (²,⁷).

Differences in healthcare access and rehabilitation around the world make TBI outcomes worse, especially in LMICs, where there is not enough trauma care and medical help is often delayed, leading to more deaths and worse results (³). This indicates that it requires improved prevention strategies, public health education, and continued research to address the global burden of TBI (²,⁵).

Pneumonia is a common complication in TBI patients, particularly those requiring prolonged mechanical ventilation. Community-acquired pneumonia (CAP) happens outside of hospitals and is usually caused by germs like Streptococcus pneumoniae and Haemophilus influenzae, while hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) occur in patients in hospitals or on ventilators, often involving tougher germs like Pseudomonas aeruginosa and MRSA, which can lead to higher death rates (³). TBI mechanisms include blunt trauma, often seen in acceleration-deceleration injuries, leading to diffuse axonal injury (DAI) and coup-contrecoup damage, commonly from falls or car accidents. Penetrating injuries from bullets or shrapnel cause localized brain damage with high infection and mortality risks (²,⁵). Hypoxic-ischemic injuries, such as those following cardiac arrest, and repetitive head trauma, often seen in athletes and military personnel, further complicate TBI management, leading to chronic traumatic encephalopathy (CTE) (⁵,⁷).

In Indonesia, TBI patients frequently develop VAP, especially in ICUs where prolonged mechanical ventilation is common (³). The prevalence of pneumonia in severe TBI patients is high, reaching up to 40% in some studies, which points to the important of stringent infection control and timely management. diagnosis and treatment, worsening patient outcomes in many regions (⁸). The long-term consequences of TBI include chronic physical, cognitive, and emotional impairments, which place a heavy burden on healthcare systems, particularly in under-resourced regions.

This study aims to evaluate the mortality rates comprehensively and identify the associated risk factors of severe traumatic brain injury (sTBI) in patients with pneumonia in Dr. Soetomo General Academic Hospital, taking into account the impact of various clinical findings, secondary CT-scan findings, and microbiological culture. The authors specifically chose sTBI since it has an increased risk of VAP, mainly due to low GCS scores and prolonged use of mechanical ventilation.

METHODS

This study employed a retrospective observational design with a case-control approach. Data collection occurred from January to December 2023, focusing on patients diagnosed with severe traumatic brain injury (sTBI) admitted to Dr. Soetomo General Academic Hospital. All patients meeting the predetermined inclusion criteria throughout the designated study period were systematically enrolled, ensuring complete population capture rather than representative sampling. This thorough method removes any bias from sampling and gives strong evidence for assessing how VAP affects the risk of death in sTBI patients. The Commission of Ethics, Dr. Soetomo Academic General Hospital, granted the ethical clearance for this study on October 29 th , 2024. (1808/LOE/301.4.2/X/2024).

The study population consisted of all patients with severe traumatic brain injury (GCS 3-8) admitted to Dr. Soetomo General Academic Hospital from January to December 2023. The inclusion criteria required patients to have a confirmed diagnosis of TBI and be admitted to the ICU. Exclusion criteria included penetrating craniocerebral injuries and cases complicated by coexisting conditions such as chronic infections and malignancies. The final sample consisted of all eligible patients during the study period.

Data were collected from patients' medical records, including written informed consent, demographic information,

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