What is the predictive value of Delta Shock Index (DSI) for mortality and clinical outcomes in trauma patients in Malaysian semi-rural trauma centers?

Delta Shock Index for Predicting Mortality and Clinical Outcomes in Malaysian Semi-rural Trauma Centers: A Research Framework

Delta Shock Index (DSI) is a superior predictor of mortality, need for blood transfusion, and ICU resource utilization in trauma patients compared to traditional vital signs and should be implemented in Malaysian semi-rural trauma centers to improve patient outcomes. 1, 2, 3

Introduction

Trauma remains a significant cause of morbidity and mortality worldwide, with particular challenges in semi-rural settings where resources may be limited and transport times prolonged. Early identification of patients at risk for poor outcomes is crucial for appropriate triage and resource allocation. While traditional vital signs and scoring systems have been used for trauma assessment, the Delta Shock Index (DSI) has emerged as a powerful predictor of clinical outcomes.

The Shock Index (SI), calculated as heart rate divided by systolic blood pressure, typically ranges between 0.5 and 0.7 in healthy adults 4. Delta Shock Index (DSI) measures the change in SI over time, providing dynamic information about a patient's hemodynamic status and response to initial interventions. Recent evidence suggests that DSI may outperform traditional measures in predicting mortality and need for interventions in trauma patients 2, 3.

Rationale of Study

Malaysian semi-rural trauma centers face unique challenges including:

• Limited resources compared to urban centers
• Longer transport times to definitive care
• Varied patient demographics and injury patterns
• Need for efficient triage tools to optimize resource allocation

Current trauma scoring systems may not be optimally calibrated for the Malaysian population and semi-rural setting. The Pan-Asian Trauma Outcomes Study (PATOS) registry provides an opportunity to evaluate the predictive value of DSI specifically in this context.

Benefits of Study

This study will:

• Provide evidence-specific to Malaysian semi-rural trauma centers
• Potentially improve trauma triage and resource allocation
• Reduce mortality through earlier identification of high-risk patients
• Optimize utilization of limited resources in semi-rural settings
• Contribute to the growing body of evidence on DSI as a predictor of outcomes
• Inform trauma care protocols specific to Malaysian healthcare system

General Objective

To evaluate the predictive value of Delta Shock Index for mortality and clinical outcomes in trauma patients presenting to Malaysian semi-rural trauma centers.

Specific Objectives

1. To determine the accuracy of DSI in predicting in-hospital mortality compared to traditional vital signs and scoring systems
2. To assess the relationship between DSI and need for blood transfusion in the first 24 hours
3. To evaluate the association between DSI and ICU admission rates and length of stay
4. To identify the optimal DSI threshold for predicting adverse outcomes in the Malaysian semi-rural trauma population
5. To analyze the performance of DSI across different trauma subgroups (blunt vs. penetrating, elderly vs. young, etc.)
6. To develop a risk stratification model incorporating DSI for Malaysian semi-rural trauma centers

Research Hypothesis

Primary hypothesis: A Delta Shock Index >0.1 will be associated with significantly higher in-hospital mortality in trauma patients presenting to Malaysian semi-rural trauma centers compared to patients with DSI ≤0.1.

Secondary hypotheses:

1. DSI >0.1 will be associated with increased need for blood transfusion
2. DSI >0.1 will be associated with longer ICU length of stay
3. DSI will demonstrate superior predictive ability for mortality compared to traditional shock index, ISS, and TRISS in this population
4. Both positive (increasing) and negative (decreasing) DSI values exceeding certain thresholds will demonstrate a J-shaped relationship with mortality

Literature Review

The shock index (SI) has been established as a valuable predictor of outcomes in trauma patients. A SI ≥0.9-1.0 has been associated with increased massive transfusion (25%), interventional radiology (6.2%), and operative intervention (14.7%) in bleeding trauma patients 4. Multiple studies have demonstrated that SI thresholds between 0.8 and 1.0 predict massive transfusion with AUROCs between 0.73 and 0.89 4.

Recent research has focused on Delta Shock Index (DSI) as potentially superior to static SI measurements. A study by the American Journal of Emergency Medicine demonstrated that DSI had significantly higher AUROC values in discriminating major injury, prolonged ICU stay, and in-hospital mortality compared to prehospital SI and SI at ED 2. This study also identified a J-shaped relationship between DSI and mortality, with both DSI <-0.5 and DSI ≥0.5 associated with significantly higher risk of in-hospital mortality 2.

A 2017 study found that ED Delta SI >0.1 was associated with increased mortality (6.6% vs 2.6%), need for blood transfusion (1764 vs 565 cc), and ICU length of stay (5.6 vs 3.8 days) compared with patients with ED Delta SI ≤0.1 5. A 2024 multicenter study found that patients with prehospital DSI >0.1 were 31% more likely to die and had twice the odds of receiving blood products within 4 hours of ED arrival 3.

The predictive value of DSI has been demonstrated in both trauma and non-trauma critically ill patients. A study in Frontiers in Medicine found that high DSI during ED stay was correlated with in-hospital mortality and early mortality in patients admitted to the ICU, with particularly strong associations in elderly patients, septic patients, and those with initial SBP <100 mmHg 6.

Research Questions

1. What is the predictive value of DSI for in-hospital mortality in trauma patients presenting to Malaysian semi-rural trauma centers?
2. How does DSI compare to traditional vital signs and scoring systems in predicting clinical outcomes?
3. What is the optimal threshold of DSI for predicting adverse outcomes in this population?
4. Does the relationship between DSI and mortality follow a J-shaped curve as suggested by previous research?
5. How does the predictive value of DSI vary across different trauma subgroups?
6. Can a risk stratification model incorporating DSI improve triage decisions in Malaysian semi-rural trauma centers?

Conceptual Framework

The conceptual framework for this study is based on the understanding that:

1. Trauma induces physiological stress and potential hemodynamic compromise
2. The body's compensatory mechanisms may initially mask significant injury
3. Changes in shock index over time (DSI) reflect the dynamic nature of the body's response to injury
4. DSI captures both deterioration and improvement in hemodynamic status
5. DSI may provide earlier warning of decompensation than traditional vital signs
6. Early identification of high-risk patients allows for more appropriate resource allocation

Study Design

This will be a retrospective cohort study using data from the Pan-Asian Trauma Outcomes Study (PATOS) registry. The study will analyze trauma patients presenting to Malaysian semi-rural trauma centers over a defined period.

Population

The study population will include all adult trauma patients (age ≥18 years) presenting to participating Malaysian semi-rural trauma centers and recorded in the PATOS registry during the study period.

Inclusion Criteria

1. Adult patients (age ≥18 years)
2. Trauma patients presenting to participating Malaysian semi-rural trauma centers
3. Patients with complete vital sign data available for calculation of DSI
4. Patients included in the PATOS registry

Exclusion Criteria

1. Patients with incomplete vital sign data
2. Patients who were dead on arrival
3. Patients transferred from other facilities without initial vital signs
4. Pregnant patients
5. Patients with pre-existing conditions significantly affecting heart rate or blood pressure (e.g., pacemakers)
6. Patients on medications significantly affecting heart rate or blood pressure without documentation

Research Tool

Data Collection

Data will be extracted from the PATOS registry, including:

1. Demographics: age, sex, comorbidities
2. Injury characteristics: mechanism, Injury Severity Score (ISS), Abbreviated Injury Scale (AIS)
3. Vital signs: heart rate and systolic blood pressure at multiple time points
4. Interventions: blood transfusion, surgical procedures
5. Outcomes: mortality, ICU admission, length of stay

Calculation of Delta Shock Index

DSI will be calculated as:

• DSI = SI at ED arrival - SI at first recorded measurement
• SI = Heart Rate / Systolic Blood Pressure

DSI will be categorized into groups for analysis:

• DSI < -0.5
• -0.5 ≤ DSI < -0.1
• -0.1 ≤ DSI < 0.1
• 0.1 ≤ DSI < 0.5
• 0.5 ≤ DSI

Statistical Analysis

1. Descriptive statistics for patient characteristics
2. Area under the receiver operating characteristic curve (AUROC) to assess predictive ability of DSI for mortality and other outcomes
3. Comparison of AUROC values between DSI and other predictors (traditional SI, ISS, TRISS)
4. Logistic regression to determine odds ratios for mortality and other outcomes based on DSI categories
5. Multivariate analysis adjusting for confounding variables (age, comorbidities, injury mechanism)
6. Subgroup analyses for different trauma populations

Expected Results

1. DSI >0.1 will be associated with increased in-hospital mortality, need for blood transfusion, and ICU length of stay
2. DSI will demonstrate superior predictive ability for adverse outcomes compared to traditional vital signs and scoring systems
3. A J-shaped relationship between DSI and mortality will be observed, with both high positive and high negative DSI values associated with increased mortality
4. The optimal threshold for DSI in predicting adverse outcomes will be identified
5. DSI will maintain predictive value across different trauma subgroups, with potential variations in optimal thresholds
6. A risk stratification model incorporating DSI will demonstrate improved predictive ability compared to existing models

This study will provide valuable evidence for the implementation of DSI in trauma triage protocols in Malaysian semi-rural trauma centers, potentially improving patient outcomes through earlier identification of high-risk patients and more appropriate resource allocation.