Discussion
The present study is the first to evaluate the quality of Japanese trauma care using large trauma registries from Japan and the USA. The results show that Japanese trauma care is largely comparable with that provided in the USA. However, the outcomes for patients who receive a blood transfusion in Japan are worse when compared with those in the USA. Both data sets had relatively low mortality rates compared with those in previous studies, which might be due to our exclusion criteria and the fact that the data were collected in recent years.1 7 However, trauma care quality in Japan is most likely improving with the adoption of various efforts, some of which were mentioned in the Introduction section.
Although it is difficult to compare the performance of different systems of trauma care delivery, the NTDB, which is currently the largest trauma-related registry, is an excellent global benchmark and is useful in the quality improvement process. Several international comparison studies show the potential for assessing the strength and weakness of different systems. In one international comparison study, trauma mortality outcomes were compared between a trauma center in France and the NTDB.7 There are significant differences in trauma management between France and the USA, especially in prehospital care and the initial attending physician who usually does not practice in the prehospital setting in the USA. The Japanese trauma system may be more similar to that in France rather than that in the USA.8 Japanese prehospital care includes ambulance and helicopter medical services with a physician. Thus, physicians can provide the initial resuscitation and make decisions regarding the necessity of surgery at the injury scene. Recently, it has been reported that helicopter transport with a physician is associated with a survival benefit in Japan.9 In another study, in-hospital trauma mortality at a South African trauma center was compared with that in matched patients from the NTDB.10 Compared with that in the NTDB, the South African trauma center had a survival disadvantage in patients with blunt trauma injuries and a lower GCS score. Thus, the authors suggested that the outcome of traumatic brain injury may be improved by creating specific protocols.10 Similarly, we found that the JTDB had a significantly higher mortality among patients who received a blood transfusion compared with that in the NTDB. There must be a specific reason for this difference and room for improvement. Finally, another international study compared outcomes of severely injured patients between a South Korean trauma center and the NTDB, and found that the implementation of a trauma system in South Korea improved trauma mortality.11 The trauma system in South Korea comprises trauma centers and was established nationwide in 2012. Japan does not have a trauma system with nationwide coverage or trauma centers as typically defined; instead, ECCCs play an alternative role. However, the facility criteria are not specific for trauma care and are very vague regarding staff assignments (online supplementary file 2). The implementation of a trauma system with government and public support could significantly improve trauma outcomes in Japan as well. Additionally, by comparing trauma outcomes in Japan with those in the USA, we were able to identify important issues for quality improvement.
There were large differences in the patient characteristics between the two countries. The most notable finding concerned the differences in the etiology and mechanism of injury. Given that Japan has a high suicide rate and a very low violent crime rate, the finding that the JTDB had a higher rate of self-inflicted injuries and fewer assaults and GSWs compared with that in the NTDB is remarkable.12 The second notable finding was the large difference in age distribution. As Japan has the highest population of elderly adults in the world, this finding is also important.13 Third, the rate of patients in extremis was higher in the JTDB than in the NTDB. Japanese prehospital providers rarely terminate resuscitative efforts at the scene and during transfer of most traumatic patients, even those with cardiac arrest due to unwitnessed blunt trauma.
Even though the inclusion criteria limited the study population to patients with ISS ≥9, the patients underwent thoracotomy or laparotomy at a very low frequency. Unlike that in the USA, Japan has an extremely low rate of GSWs. Attending trauma surgeons have a limited number of surgery cases in Japan, and this is a major issue in the training of trauma surgeons. Therefore, inhouse attending trauma surgeons are still uncommon and emergency physicians usually provide initial trauma management for severely injured patients in Japan. ECCCs in Japan do not have any facility criteria requiring a surgeon to be present for major resuscitations, which the ACS-COT mandates for trauma center verification.14 Not having an on-call trauma surgeon potentially causes a delay in urgent or emergent surgery.15 However, patients in the JTDB who underwent thoracotomy or laparotomy did not have worse outcomes. On the other hand, patients who required blood transfusion, who may be regarded as patients with active hemorrhage, had worse outcomes in the JTDB than in the NTDB. The lack of an inhouse attending trauma surgeon may cause a delay in surgery for hemorrhage control in Japan. Additionally, a massive transfusion protocol (MTP) still remains uncommon in Japan. Thus, the establishment of an inhouse trauma surgeon and MTP may improve survival outcomes in Japan.
There were large discrepancies in the length of hospital stay between the JTDB and NTDB (18.0 (7.0–35.0) days vs. 5.0 (3.0–9.0) days, before matching). The long length of stay in Japan and short length of stay in the USA are consistent with the Organisation for Economic Co-operation and Development (OECD) 2015 data.5 This result may be due to differences in the healthcare system between Japan and the USA. The OECD reported that Japan has the highest number of hospital beds per capita, nearly five times as many as that in the USA (13.2 vs. 2.8 per 1000 people); however, healthcare spending in Japan is less than that in the USA (11.4% vs. 16.6%, as a share of the gross domestic product). The self-pay burden of patients is also low in Japan, as Japan has a universal health insurance system and the High-Cost Medical Expense Financial Plan extends to almost all citizens.16 Therefore, most trauma patients and families hope to stay in the hospital for as long as possible in Japan. In fact, Japan has the highest average length of stay in the OECD countries (17.2 days). Similarly, the ICU length of stay was statistically longer in JTDB than in the NTDB; however, the difference was small compared with that for the length of hospital stay (3.0 (1.0–11.0) days vs. 3.0 (2.0–7.0) days, before matching). This may be due to that fact that decisions regarding ICU discharge made by emergency physicians are largely independent of the patient’s wishes.
In spite of a lack of a large difference in overall mortality between the two countries, it appears that the treatment strategy differs between Japan and the USA. There is one aspect worthy of note: the use of diagnostic imaging. CT scans were used nearly 35% more often in the JTDB than in the NTDB cohort. These data suggest that CT may be overused in Japan. Several reasons have been proposed for the higher use of CT in Japan. First, most Japanese ECCCs are equipped with high-speed CT scanners located very close to the trauma bay. In recent years, several hospitals have also installed hybrid emergency room-enabled interventional radiology systems. This technology has dramatically reduced the time required for completion of CT scans in Japan.17 Thus, most Japanese emergency physicians will readily consider CT as safe as long as the patient has preresuscitation SBP greater than 75 mm Hg.18 Trauma surgeons do not necessarily attend the initial care for severely injured patients in Japan. Therefore, there may be enough time to undergo CT scanning before the completion of the definitive surgical assessment. Although an overuse of CT scanning becomes an issue of facility resources and cost, CT scanners are widely available, cost is moderate, and reimbursed by the universal health insurance in Japan. Japan has the highest number of CT scanners in the world, more than twice as many as those in the USA (101 vs. 44 per million people).5
The present study has several limitations, including its retrospective nature. Additionally, although exact matching was performed to minimize confounding effects, there may be other unmeasured confounders. For example, Japan has the highest life expectancy in the world.5 Therefore, patients included in the JTDB may be in better physical health than those in the NTDB data set. Furthermore, the data sets have other potentially important differences, including social, economic, and racial differences. As for trauma management, differences in clinical protocols largely depend on each hospital, as well as the care delivery system in each country. These factors may strongly affect overall outcomes. Furthermore, both data sets have a number of limitations. They comprise voluntarily submitted data from hospitals that are actively involved in trauma care (convenience sample). Furthermore, the injury-related data have variability and inaccuracy in scoring.19 The JTDB also lacks a data verification system. Therefore, selection and information biases are evident. Additionally, in-hospital mortality was the only outcome evaluated. The in-hospital mortality may underestimate the importance of other patient outcomes to a greater extent in the NTDB compared with the JTDB because the JTDB had a significantly longer hospital length of stay than that in the NTDB. Finally, the NTDB may have higher rates of occult injuries due to a lower use of CT scans. Therefore, the ISS in the NTDB may be underestimated. Despite these limitations, the present study clarifies differences in clinical practice with a national perspective. The study results should provide a better understanding of Japanese clinical practices and facilitate international clinical studies.