Ten-year in-hospital mortality trends among Japanese injured patients by age, injury severity, injury mechanism, and injury region: A nationwide observational study.

The Injury Severity Score (ISS) is widely used in trauma research worldwide. An ISS cutoff value of ≥16 is frequently used as the definition of severe injury in Japan. The mortality of patients with ISS ≥16 has decreased in recent years, owing to the developing the trauma care system. This study aimed to analyze the prevalence, in-hospital mortality, and odds ratio (OR) for mortality in Japanese injured patients by age, injury mechanism, injury region, and injury severity over 10 years. This study used the Japan Trauma Data Bank (JTDB) dataset, which included 315,614 patients registered between 2009 and 2018. 209,290 injured patients were utilized. This study evaluated 10-year trends of the prevalence and in-hospital mortality and risk factors associated with in-hospital mortality. The overall in-hospital mortality was 10.5%. During the 10-year study period in Japan, the mortality trend among all injured patient groups with ISS 0-15, 16-25, and ≥26 showed significant decreases (p <0.001). Moreover, the mortality risk of patients with ISS ≥26 was significantly higher than that of patients with ISS 0-15 and 16-25 (p <0.001, OR = 0.05 and p<0.001, OR = 0.22). If we define injured patients who are expected to have a mortality rate of 20% or more as severely injured, it may be necessary to change the injury severity definition according to reduction of trauma mortality as ISS cutoff values to ≥26 instead of ≥16. From 2009 to 2018, the in-hospital mortality trend among all injured patient groups with ISS 0-15, 16-25, and ≥26 showed significant decreases in Japan. Differences were noted in mortality trends and risks according to anatomical injury severity.