Agreement Between Standard and ICD-10-Based Injury Severity Scores

Abstract

Introduction

Injury Severity Score (ISS) is used to describe anatomical lesions. ISS is traditionally determined through medical record review (standard ISS), which requires specific training and may be time-consuming. An alternative way to obtain ISS is by use of ICD-9/10 injury diagnoses, and several conversion tools exist. We sought to evaluate the agreement between standard ISS and ISS obtained with two tools converting ICD-10 diagnoses.

Methods

Our cohort consisted of trauma patients ≥18 years admitted to Rigshospitalet between 1999 and 2016. The included patients had standard ISS recorded in the Trauma Audit and Research Network (TARN) database (ISS-TARN), and ICD-10 injury diagnoses for the trauma contact were recorded in the Danish National Patient Registry. We used the tools ICDPIC-R and ICD-AIS map to calculate ISS based on ICD-10 diagnoses. ICDPIC-R provided two ISSs: ISS-TQIP and ISS-NIS. The ICD-AIS map resulted in one ISS: ISS-map. The ISS-TARN was compared to the conversion tool ISSs using Bland-Altman plots. The agreement between ISS-TARN and the conversion tool ISSs for ISS above 15 was assessed using kappa statistics (κ).

Results

We included 4308 trauma patients. The median age was 44 years, 70% were male, and 92% had a blunt injury mechanism. The median ISS-TARN was 16 [IQR: 9–25], and the median conversion tool ISSs were 10 [2–25] (ISS-TQIP), 17 [5–26] (ISS-NIS), and 9 [4–16] (ISS-map). The Bland-Altman plots all showed increasing difference in ISS with increasing mean ISS. Bias ranged from −7.3 to 1.1 and limits of agreement ranged between −28.0 and 25.7. The agreement for ISS above 15 was fair to moderate (κ = 0.43 (ISS-TQIP), 0.44 (ISS-NIS), and 0.29 (ISS-map)).

Conclusion

Using ICDPIC-R or ICD-AIS map to determine ISS is feasible, but limits of agreement were unacceptably wide. The agreement between ISS-TARN and ICDPIC-R was moderate for ISS above 15.

Keywords:

• trauma
• injury coding
• ISS
• ICD

Abbreviations

AAAM, Association for the Advancement of Automotive Medicine; AIS, Abbreviated Injury Scale; DNPR, Danish National Patient Registry; ICD, International Classification of Diseases; ICDPIC-R, Programs for Injury Categorization using the ICD and R statistical software; IQR, Interquartile Range; ISS, Injury Severity Score; NIS, National Inpatient Sample; RH, Rigshospitalet; TARN, Trauma Audit and Research Network; TQIP, Trauma Quality Improvement Program; WHO, World Health Organization.

Data Sharing Statement

The data used in this research project cannot be shared due to the rules and regulations set forward by Statistics Denmark.

Ethics Approval and Informed Consent

No consent or ethics committee was required for registry studies according to Danish law.

Disclosure

The authors have no competing interests.

Additional information

Funding

The study was financially supported by The Research Fund of Rigshospitalet, University of Copenhagen. These materials have received financial support from The Danish Victims Fund (grant number 19-610-00046). The execution, content, and results of the materials are the sole responsibility of the authors. The analysis and viewpoints that have been made evident from the materials belong to the authors and do not necessarily reflect the views of The Council of The Danish Victims Fund.