Outcome Measurements
In addition to basic demographic variables, outcome variables following the emergency visit included subsequent hospitalization rate, length of stay and 30-day mortality. The database is linked to Taiwan’s national cause of death registry, enabling the assessment of 30-day mortality.
Cases were classified based on ICD codes into the following injury categories:
• Minor injuries: this category was defined by diagnoses that did not involve fractures or internal organ injuries. It primarily included ICD-9 and ICD-10 codes representing abrasions, contusions, sprains/strains, and superficial open wounds.
• Skull fractures or intracranial hemorrhages: ICD-10 codes S02, S06 or ICD-9 codes 800, 801, 802, 803, 804, 850, 851, 852, 853, 854.
• Spinal fractures and neurological injuries: ICD-10 codes S12, S14, S22.0, S32.0, S32.1, S32.2, S32.9, S24, S34 or ICD-9 codes 805, 806, 905, 907, 952.
• Severe chest injuries: ICD-10 codes S22.2, S22.3, S22.4, S22.5, S27 or ICD-9 codes 807, 860, 861, 862.
• Severe abdominal and pelvic injuries: ICD-10 codes S36, S32.3, S32.4, S32.5, S32.6, S32.7, S32.8 or ICD-9 codes 863, 864, 865, 866, 867, 868, 808, 902, 926.
• Upper limb fractures and crush injuries: ICD-10 codes S42, S47, S52, S57, S62, S67 or ICD-9 codes 808, 810, 811, 812, 813, 814, 815, 816, 867, 868, 927.
• Lower limb fractures and crush injuries: ICD-10 codes S72, S75, S77, S82, S87, S92, S97 or ICD-9 codes 820, 821, 822, 823, 824, 825, 826, 896, 928.
• Burns: ICD-10 codes T20, T21, T22, T23, T24, T25, T26 or ICD-9 codes 940, 941, 942, 943, 944, 945, 947, 948, 949.
• Major trauma: defined by ICD-10 code T07 (unspecified multiple injuries). This category inherently overlaps with other specific injuries (e.g., fractures) but is analyzed distinctly. In Taiwan, T07 serves as a specific clinical and administrative marker for severe polytrauma (often Injury Severity Score ≥16).