Predicting mortality with the international classification of disease injury severity score using survival risk ratios derived from an Indian trauma population: A cohort study

The International Classification of Disease Critical Care Severity Score demonstrates that pediatric burden of injury is similar to that of adults: Validation using the National Trauma Databank☆

BACKGROUND/PURPOSE

Resource-based severity of injury (SOI) measures, such as the International Classification of Disease (ICD) Critical Care Severity Score (ICASS), may characterize traumatic burden better than standard mortality-based measures. The purpose of this study was to validate the ICASS in a representative national-level trauma cohort and compare SOI measures between children and adults.

METHODS

The National Trauma Databank was used to derive (2008-12) and validate (2013-15) ICASS and ICD Injury Severity Scores (ICISS, standard mortality-based SOI measure). SOI metrics and outcomes were compared between pediatric, adult, and elderly age groups. Logistic regression modeling evaluated predictors of critical care resource utilization.

RESULTS

Derivation and validation cohorts consisted of 3.90 and 1.97 million patients, respectively. ICASS strongly predicted actual critical care utilization (OR 1.04, 95% CI 1.04-1.04, p<0.0001). Mean ICASS was 24.4 for children and 33.0 for adults (ratio 0.74), indicating predicted critical care utilization in children was three-quarters that of adults. In contrast, predicted pediatric mortality was less than half that of adults.

CONCLUSIONS

Mortality-based SOI measures underestimate pediatric burden of injury. This study validates ICASS and demonstrates that pediatric resource-based SOI is more similar to that of adults. ICASS is easily calculated without a trauma registry and complements mortality-based measures. Level of evidence III, retrospective comparative study.

International classification of disease based injury severity score (ICISS): A data linkage study of hospital and death data in Victoria, Australia

BACKGROUND

Surveillance of severe injury incidence and prevalence using ICD-based injury severity scores (ICISS) requires valid, locally applicable diagnosis-specific survival probabilities (DSPs). This study aims to derive and validate ICISS in Victoria, Australia, and compare various ICISS methodologies in terms of accuracy and calculated severe injury prevalence.

METHODS

This study used injury admissions (ICD-10-AM coded) from the Victorian Admitted Episodes Database (VAED) linked with death data (Cause of Death - Unit Record Files: CODURF). Using design data (July 2008 - June 2014; n = 720,759), various ICISS scales were derived, based on (i) in-hospital and (ii) three-month mortality. These scales were applied to testing data (July 2014 - December 2016; n = 334,363). Logistic regression modelling was used to determine model discrimination and calibration.

RESULTS

In the design data, there were 6,337(0.9%) hospital deaths and 17,514(2.4%) three-months deaths; in the testing data, there were 2,700(0.8%) hospital deaths and 8,425(2.5%) three-month deaths. Newly developed ICISS scales had acceptable to outstanding discrimination, with Area Under the Curve ranging from 0.758 to 0.910. Age-specific ICISS scales were superior to general ICISS scales in model discrimination but inferior in model calibration. Calculated severe injury (ICISS ≤0.941) prevalence in the testing data ranged from 2% to 24%, depending on which mortality outcomes were used to calculate DRGs.

CONCLUSIONS

This study provides local, validated ICISS scores that can be used in Victoria. It is recommended that age group stratified ICISS based on the worst-injury method is used. From the comparison of various ICISS scores, reflecting the range of ICISS permutations that are currently in use, care should be taken to compare ICISS methodology before comparing severe injury prevalence per population, injury cause, and time trends.

External validation of International Classification of Injury Severity Score to predict mortality in a Greek adult trauma population

INTRODUCTION

The International Classification of diseases- based Injury Severity Score (ICISS) obtained by empirically derived diagnosis-specific survival probabilities (DSPs) is the best-known risk-adjustment measure to predict mortality. Recently, a new set of pooled DSPs has been proposed by the International Collaborative Effort on Injury Statistics but it remains to be externally validated in other cohorts. The aim of this study was to externally validate the ICISS using international DSPs and compare its prognostic performance with local DSPs derived from Greek adult trauma population.

MATERIALS AND METHODS

This retrospective single-center cohort study enrolled adult trauma patients (≥ 16 years) hospitalized between January 2015 and December 2019 and temporally divided into derivation (n = 21,614) and validation cohorts (n = 14,889). Two different ICISS values were calculated for each patient using two different sets of DSPs: international (ICISSint) and local (ICISSgr). The primary outcome was in-hospital mortality. Models' prediction was performed using discrimination and calibration statistics.

RESULTS

ICISSint displayed good discrimination in derivation (AUC = 0.836 CI 95% 0.819-0.852) and validation cohort (AUC = 0.817 CI 95% 0.797-0.836). Calibration using visual analysis showed accurate prediction at patients with low mortality risk, especially below 30%. ICISSgr yielded better discrimination (AUC = 0.834 CI 95% 0.814-0.854 vs 0.817 CI 95% 0.797-0.836, p ˂ .05) and marginally improved overall accuracy (Brier score = 0.0216 vs 0.0223) compared with the ICISSint in the validation cohort. Incorporation of age and sex in both models enhanced further their performance as reflected by superior discrimination (p ˂ .05) and closer calibration curve to the identity line in the validation cohort.

CONCLUSION

This study supports the use of international DSPs for the ICISS to predict mortality in contemporary trauma patients and provides evidence regarding the potential benefit of applying local DSPs. Further research is warranted to confirm our findings and recommend the widespread use of ICISS as a valid measure that is easily obtained from administrative data based on ICD-10 codes.

Fatal and Nonfatal Injury Patterns of Stranded Motorists

Because nonfatal and fatal incidents for stranded motorists are not separated from vehicular accidents, little data are available on incident characteristics. To close this gap, data fields were inserted into databases at a medical examiner's office and two trauma centers to collect injury-related information. Forensic nurses and pathologists aided in forming a collaboration among the agencies involved and supported data collection efforts. Data collected over a 5-year period were examined for injury patterns to determine risk factors affecting these patterns. Of the total sample (N = 219), 24.7% had spinal injuries resulting in fatal injuries for 46 of 54 individuals. The odds were stranded motorists with spine-related injuries (C1-C7) had 9.13 times higher risk for a fatal outcome compared with those without spine-related injuries. Severe injuries (Abbreviated Injury Scale scores ≥ 4) noted for head/neck (29.7%) and chest (24.2%) were significantly associated with fatality. Of the 219 cases, 22.8% were inside of a stopped vehicle, and 77.2% were outside a vehicle at the time of injury. Outcomes illustrated the success of the interprofessional collaboration between trauma centers and a medicolegal death investigation agency that resulted in data useful for forensic nurses and pathologists documenting evidence, emergency and trauma responding personnel in patient priority stabilization, and injury prevention specialists for highway safety programs.