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Development and validation of a new ICD-10-based trauma mortality prediction scoring system using a Japanese national inpatient database
  1. Tomoki Wada1,
  2. Hideo Yasunaga2,
  3. Hayato Yamana2,
  4. Hiroki Matsui2,
  5. Takehiro Matsubara1,
  6. Kiyohide Fushimi3,
  7. Susumu Nakajima1
  1. 1Department of Emergency and Critical Care Medicine, The University of Tokyo Hospital, Tokyo, Japan
  2. 2Department of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo, Tokyo, Japan
  3. 3Department of Health Policy and Informatics, Tokyo Medical and Dental University, Tokyo, Japan
  1. Correspondence to Dr Tomoki Wada, Department of Emergency and Critical Care Medicine, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-8655, Japan; wadat-eme{at}


Introduction To develop and validate a new trauma mortality prediction scoring system based on International Statistical Classification of Diseases (ICD)-10 codes, using a Japanese administrative claims and discharge abstract database.

Methods This retrospective observational study used the Japanese Diagnosis Procedure Combination database. Injuries were categorised into 33 groups with 5 additional groups based on injury sites and types. A multivariable logistic regression analysis was performed for in-hospital mortality in a derivation cohort after adjusting for the 38 groups, patient's sex, age and Charlson Comorbidity Index score. Each variable was assigned a score that was equal to the value of the regression coefficient. The new severity score was defined as the sum of the scores. The new scoring system was tested in a validation cohort.

Results The mortality rates were 2.4% (9270/393 395) and 2.5% (8778/349 285) in the derivation and validation cohorts, respectively. The area under the receiver operating curve (AUROC) of the new scoring system was 0.887 (95% CI 0.884 to 0.890) in the validation cohort. Subgroup analyses showed that the scoring system retained high predictive performance both for patients <65 years (AUROC 0.934, 95% CI 0.928 to 0.939) and for elderly patients at the age of ≥65 years (AUROC 0.825, 95% CI 0.820 to 0.829).

Conclusions A new ICD-10-based injury severity scoring system was developed and validated. Further studies are required to validate the scoring system in other databases.

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