Comparing injury severity scores from trauma registries with those mapped from injury diagnosis codes in injured adolescents

<b>Background</b>: Injury severity classification is crucial for trauma-related clinical care, quality improvement, and research. This study compared injury severity score (ISS) values derived from the abbreviated injury scale (AIS) scores assigned by trauma registry coders (trauma registry ISS) to those mapped from the International Classification of Diseases (ICD) codes (map-derived ISS) in adolescents. <b>Methods</b>: Data were collected from electronic health records of 1259 adolescent trauma patients from ten US paediatric trauma centres. Trauma registry ISS values served as the gold standard, while map-derived ISS values were calculated using ICD-10 codes mapped to AIS scores. ISS values were compared using descriptive analyses, Wilcoxon tests, and correlation assessment. <b>Results</b>: Median ISS values were similar between the trauma registry (median: 8.0 and IQR: 4-13) and map-derived ISS (median: 9.0 and IQR: 4-10), with significant differences observed at two of the ten centres. Exact match accuracy between trauma registry and map-derived ISS values was 27.2%, increasing to 69.3% when a ±5-point range was considered. The overall correlation was moderate (r=0.48, p<0.001), and there was decreased concordance with increasing injury severity. <b>Conclusions</b>: There were discrepancies between trauma registry and map-derived ISS, especially for more severe injuries.