Effect of the Profit and Teaching Status of Hospitals on the Patterns and Outcomes of Abdominal Aorta and Inferior Vena Cava Injuries after Severe Abdominal Trauma

Background The inferior vena cava (IVC) and the abdominal aorta (AA) are two important blood vessels located in the abdomen. The outcomes of such injuries rely heavily on the experience, expertise, and resources available at the hospital where the patient is treated. However, our current understanding of the potential impact of the hospital profit and teaching status on surgical outcomes in the context of traumatic injuries to the IVC and AA remains limited, making it important to investigate the potential association between these hospital characteristics and patient outcomes to enhance the quality of care and optimize treatment strategies. Objective This study aimed to compare demographics, trauma characteristics, and outcomes between nonprofit status (NPSH) and for-profit hospital status (FPSH), as well as among community hospitals (CHs), nonteaching hospitals (NTHs), and university hospitals (UHs), in patients with severe abdominal trauma and abdominal aorta injury (AAI), inferior vena cava injury (IVCI), and both (AAI + IVCI). Methods Demographics, trauma, and outcome measures associated with AAI, IVCI, and AAI + IVCI were compared between the different profit and teaching status groups using NTDB. Multivariate regression was used to identify independent factors associated with death under care (DUC). Results In the 2017 NTDB-RDS, 1,479 patients met the inclusion criteria, resulting in an overall incidence of 0.17% for AAI, IVCI, and AAI + IVCI after severe abdominal trauma. More patients died under care in the FPSH group than in the NPSH group (nonprofit vs. for-profit: 60.3% vs. 47.2%; P < 0.001). The results indicated that FPSH independently affected DUC. NTH had no significant effect on DUC; although the in-hospital complication rate varied with NTH, no independent association was observed. Conclusions The study findings demonstrated that in patients with severe abdominal trauma, including injuries to AAI, IVCI, or both (AAI + IVCI), the profit status of hospitals, rather than the teaching status, had a substantial influence on DUC. Future studies should examine differences in the volume of cases and levels of trauma centers to better understand how to improve patient outcomes in FPSH.


Introduction
Te abdominal aorta (AA), the largest artery in the abdomen, carries oxygen-rich blood from the heart to the lower body. Te inferior vena cava (IVC) is the largest vein in the abdomen and carries deoxygenated blood back to the right atrium [1]. AA and IVC constitute the major blood vessels in the abdomen and are essential for proper body function. As expected, trauma to these vessels can be life-threatening and requires immediate medical attention. IVC injury (IVCI) remains a severe problem in the operating room because it generates signifcant blood loss and has a high mortality rate. Abdominal aorta injury (AAI) is also potentially fatal, accounting for 0.1% of all trauma hospitalizations [2].
Despite breakthroughs in diagnosis and management, these traumas are associated with substantial morbidity and fatality rates [3], and because AAI and IVCI are rare, their clinical features are not well understood. Furthermore, the reported prevalence and outcomes vary among studies due to diferences in expertise and facilities available at hospitals.
Te lack of uniformity in the number of cases across different study centers makes it challenging to accurately determine mortality rates adjusted for the number of patients with these conditions and to analyze other related factors [1]. Te healthcare community debates whether the outcomes of medical care vary depending on the hospital's teaching status (TS) [4][5][6][7]. Teaching hospitals are commonly considered to provide high-quality treatment, with public opinion generally favoring them. Studies suggest that the major TS is associated with lower mortality rates for common conditions than non-TS hospitals [5,6]. Similarly, there has been signifcant interest in examining the efect of for-proft hospitals (FHSs) on care and outcomes [8,9]. To properly handle IVCI and AAI, hospitals require specialist resources and facilities, given the complexity of these injuries. A robust postoperative care system with access to critical care and expert nursing is essential to manage potential difculties and ensure optimal recovery. Given such constraints, the proftability and teaching status of hospitals can become relevant factors [4,[6][7][8][9]. As nonprofts, some hospitals may be better positioned to devote resources to essential care services based on their distinct focus and goals. Teaching hospitals often attract highly qualifed medical personnel by focusing on training and research. Tey also provide specialized training programs that add to the expertise available for managing challenging IVCI and AAI cases. Investigating how the hospital proft status and teaching status impact patient outcomes is crucial to ensure that hospitals have the knowledge, efective trauma systems, and infrastructure necessary to deliver improved results for IVCI and AAI patients [4].
Te National Trauma Data Bank (NTDB) is a large database that collects and houses data on trauma patients from hospitals in the United States. It aims to improve the quality of care for trauma patients by providing a centralized data source for researchers, healthcare providers, and policymakers. NTDB is updated annually and contains data from more than 1,000 hospitals in the United States. It is a valuable resource for anyone interested in understanding the epidemiology and treatment of traumatic injuries, and its data have contributed to signifcant advances in trauma care over the past several decades. However, to our knowledge, no NTDB study has examined the efect of THS and FHS on the care and outcomes of patients with severe abdominal trauma, IVCI, and AAI.
Tis study aimed to examine the pattern and outcome of AAI and IVCI in hospitals with diferent teaching statuses (TSs) and proft statuses (PSs). Eforts were made to identify the factors independently associated with death under care (DUC) in patients with severe abdominal trauma, AAI, and IVCI.

Methodology
We retrospectively analyzed secondary data from the 2017 National Trauma Data Bank Research Dataset (NTDB-RDS). Patients with AAI and/or IVCI were identifed using the International Classifcation of Diseases ICD-10-CM diagnosis code (S35.0 or S35.1) and were stratifed according to the type of injury (AAI, IVCI, and AAI + IVCI), PS (forproft status hospital (FPSH) and nonproft hospital (NPSH)), and TS (community hospital (CH), nonteaching hospital (NTH), and university hospitals (UH)). Only patients with severe abdominal trauma (abbreviated injury scale (AIS) grade ≥ 3) were included. DUC included all inhospital mortality cases. Demographic and trauma-related characteristics included age, sex, race, ISS, SBP, Glasgow Coma Scale (GCS) score, and AIS score. Outcome measures included DUC, sepsis, and overall complication rates. Demographic characteristics and outcome measures were collected and compared between the groups.
We employed STATA 16 statistical software to analyze the data, and statistical signifcance was set at P < 0.05. We used the Mann-Whitney U and Kruskal-Wallis tests for continuous variables after confrming nonnormal distribution, chi-square for categorical variables, and logistic regression for ORs. For DUC and in-hospital complications, we calculated the odds ratios (ORs) by age, ISS, SBP, GCS, AAI/IVCI, TS, and NPSH.
Te median LOS (IQR) (hospital) was 5.0 (1.0, 15.0) days. Approximately 43.9% of the patients had AAI, 51.0% had IVCI, and 5.1% had both ( Figure 1). A total of 48.1% of the patients died during care, and the complication rate was 34.0%. Te prevalence of sepsis was 4.7%. Figures 2(a) and  ; P � 0.673). Te type of injury and trauma mechanism were not signifcantly diferent between the two groups, with frearms being the most common mechanism and penetrating and blunt trauma, accounting for more than 99% of cases. Te racial makeup of the patients did not difer signifcantly between the NPSH and FPSH groups. However, there was a signifcant diference in the number of hospital beds, with 44.7 percent of the nonproft hospitals having more than 600 beds compared to 10.3 percent of FPSH (P < 0.001). Trauma-level centers were also signifcantly diferent, with a higher proportion of level 1 trauma centers in nonproft hospitals (nonproft vs. for-proft: 39.1% vs. 78.4%; P < 0.001). Although the type of injury and trauma mechanism did not difer between the two groups, there was a slight diference in the pattern of the type of intent, which was statistically signifcant.

Teaching Status.
Most of the patients (>50%) received treatment in the UH. Te age of patients admitted to CH, NTH, or UH was not signifcantly diferent (CH vs. NTH vs.  Table 2). Similarly, there were no signifcant diferences in the percentage of patients with ISS > 25 (CH vs. NTH vs. UH: 69.7% vs. 65.9% vs. 72.4%; P � 0.924). Te type of injury and trauma mechanism was also not significantly diferent between the hospital types, with frearms being the most common mechanism and penetrating and blunt trauma, accounting for over 99% of the cases. Te racial makeup of the patients was also similar between nonprofts and FPH. However, the number of hospital beds difered signifcantly, with >600 beds in 27.7%, 26.2%, and 49.7% of CH, NTH, and UH, respectively (P < 0.001). Trauma-level centers were also signifcantly diferent, with 49.8%, 13.8%, and 94.6% of level 1 trauma centers in CH, NTH, and UH, respectively (P < 0.001). However, the type, mechanism, and intent of the injury did not difer signifcantly between the three hospital groups.

Factors Afecting DUC.
Multivariate analysis was performed to investigate whether TS or PS afected DUC and inhospital complications (Tables 3 and S3). Te analysis considered common predictors such as age, systolic blood pressure (SBP), GCS, injury severity score (ISS), AAI/IVCI, TS, and PS. Te results indicated that PS was an independent risk factor for DUC, in addition to ISS, SBP, GCS, and AAI/ IVCI. Te analysis also yielded a receiver operating characteristic (ROC) curve with an area under the curve (AUC) of approximately 0.9, suggesting that the model had good predictive power. Interestingly, the subgroup analysis showed substantial variations in complication rates, number of beds, and level 1 trauma centers in CH, NTH, and UH. As a result, we used multivariate analysis to identify predictors of complications by including common characteristics, such as age, ISS, SBP, GCS, PS, and TS. Unfortunately, the quality of the regression model was inadequate (ROC � 0.55); therefore, these data were not included in this study. It is worth noting that the model did not fnd an independent relationship between the complication rate and TS or PS (Table S3).

Discussion
Traumatic abdominal vascular injuries are often serious, and trauma management can be challenging due to high rates of mortality and complications [10]. Tis study sought to explain DUC in patients with these injuries and examine whether TS and PS can infuence the mortality rate. It is noteworthy that our study found that PS and type of vascular injury (AAI, ICVI, or both) afected the mortality rate, in addition to commonly expected variables such as age, injury severity, coma status, and hemodynamic stability.
Our study did not fnd evidence of racial bias or preference in patients who underwent AAI/IVCI treatment at FPSH or NPSH. Tere were also no signifcant diferences in age, trauma, intent, mechanism, or type between the PS types. However, there were some notable diferences, such as the proportion of hospitals with 600+ beds being higher in NPSH, with level 1 trauma centers almost doubling. Patients in the NPSH group also had longer stays than those in the FPSH group. Te frequency of DUC was signifcantly higher in the FPSH group although there were no signifcant differences in the SBP, GCS, and ISS scores. When using multivariate logistic regression to identify predictors of DUC, the PS status was found to be independently associated with the risk of DUC, as well as common factors such Interestingly, TS did not have any signifcant efect on DUC. Te TS subgroup analysis did not reveal any diferences in DUC; therefore, the results of the multivariate analysis were in line with expectations. Interestingly, the subgroup analysis revealed signifcant diferences in the rates of complications, number of beds, and level 1 trauma centers among CH, NTH, and UH. Terefore, we performed multivariate analysis to identify predictors of complications, including common factors such as age, ISS, SBP, GCS, PS, and TS. Unfortunately, the quality of the regression model was poor (ROC ∼ 0.55); therefore, these fndings were not included in this study. It should be noted that the model did not demonstrate any independent association between the complication rate and TS or PS (Table S2). In a recent study, Elkbuli et al. examined popliteal vascular injury in diferent TS subgroups. Tese authors found that patients with popliteal vascular injuries treated at a CH had a mortality risk 12.3 times higher than those treated at another hospital Emergency Medicine International with similar injuries. Similarly, patients treated at a university hospital had a mortality risk 5.6 times higher than those treated at a nonteaching hospital. However, after accounting for confounding factors, these diferences were no longer statistically signifcant [11]. Our study also found diferences in the complication rates between these types but no signifcant diferences in terms of DUC. In addition, our study found that AAI/IVCI had a high DUC (48.1%) and that there were substantial disparities among AAI (DUC � 40%), IVCI (DUC � 50%), and combined AAI + IVCI (DUC � 80%). Blunt AAI has historically been associated with signifcant morbidity and mortality [12] although mortality in patients who survive presentation tends to decrease [2,13]. Branco et al. conducted a study on AAI caused by BT or PT and discovered that the mortality rate following AAI was 30.4% in 2002 and jumped to 66.0% in 2014 for PT. However, for BT, the mortality rate after AAI decreased from 58.3% in 2002 to 26.2% in 2014 [14]. de Mestral et al. conducted a study using NTDB to investigate the pattern, treatment, and in-hospital outcomes of patients with blunt AAI. Teir fndings indicated that the mean ISS was 35 ± 14, most patients experienced injuries from motor vehicle accidents, and the overall mortality rate was 29% [15]. Another notable study found that among 392,315 blunt trauma patients, 113 (0.03%) had AAI. Te median age of the patients was 38 years, and the ISS was 34. Te predominant cause of injury was motor vehicle accidents (60%), and hypotension was observed in 47% of cases, along with spinal fractures (44%) and pneumothorax or hemothorax (42%) as signifcantly related complaints. Most deaths (68%) were due to hemorrhage or cardiac arrest and occurred during the frst 24 hours [16]. Te frst NTDB study on AAI, involving 3,114 patients, found an overall incidence of 0.3%. Compared to matched controls, AAI resulted in a higher mortality rate (55% vs. 15%) and independently contributed to mortality. Tis study was the frst to defne the incidence of BAI using NTDB [17]. Shalhub et al. discovered that blunting an AAI is a rare injury, with fewer than 200 cases reported at the time. Tese authors found a median ISS of 45 and 39%, respectively, for hypotensive individuals. Te overall mortality rate was 32% [18,19].
In our study, which focused only on patients with severe abdominal trauma, the incidence rate of AAI/IVCI was 0.17%. Tis low number can be attributed to the study's focus on only severe cases. In our study, the mortality rate was approximately 50%, refecting the severity of these injuries and highlighting the importance of appropriate trauma treatment at the emergency response and hospital level. Tis study examined the demographics, injury patterns, mortality, and complication rates in hospitals with diferent PS and TS statuses. Our results indicate that despite breakthroughs in resuscitation and critical care, they remain extremely lethal. Few studies have examined the impact of PS and TS, which are rare in trauma management. When looking at the mortality rates for specifc categories of injuries, it was found that individuals with AAI performed better than those who had IVCI or a combination of AAI and IVCI. However, unlike Elkbuli et al., who found that this pattern depends on TS [11], we did not observe any signifcant variation in mortality associated with TS. Our results support those of a systematic review of the impact of TS, revealing that TS does not signifcantly infuence clinical outcomes. However, variations in individual diseases cannot be ruled out although they are unlikely to be signifcant [4].
However, we observed the lowest complications in the UH group, supporting the hypothesis of Chiu et al. that UHs are more experienced in managing vascular injuries because they see a higher volume of these types of patients. FPSH is associated with higher inpatient mortality, length of stay, and hospital charges than their nonproft counterparts [9]. However, we did not fnd any proof that FPSH preferentially serves healthier patients, delivers less evidence-based treatment, reduces hospital stays, or has patients with worse acute outcomes than nonproft facilities [8]. In our study, the volume of cases handled in the UH was more signifcant than that of the total number of cases handled by the CH and NTH. Te same reasoning may also explain, at least in part, the lower DUC in PS. It is reasonable to assume that they handled almost ten times more cases in 2017, demonstrating their greater experience in managing such cases. Another factor could be the level of trauma since almost 80% of the trauma centers in the NPS were level 1 compared to only 40% in the FPSH.

Limitations.
Tis study has certain limitations, primarily stemming from the utilization of a retrospective database. In addition, reliance on user-contributed data within NTDB introduces the possibility of injury misclassifcation, complications, inconsistent reporting, and substantial variability. Tese factors may have infuenced the DUC rates reported in this study. Furthermore, it should be noted that the NTDB dataset does not encompass improved prehospital treatment or the transfer of critically wounded patients from the accident scene to a trauma center, which could potentially account for the increased fatality rate. Another constraint lies in the incompleteness and missing data points within NTDB, limiting researchers' ability to draw comprehensive conclusions or make inferences regarding certain aspects of patient injury and care. Te generalizability of the fndings to broader populations is also subject to caution, as NTDB primarily includes trauma centers within the United States, potentially limiting its applicability to other countries or individuals not seeking care at trauma centers. Furthermore, inconsistencies in data collection and reporting across institutions can introduce bias, which afects the reliability and validity of the data. While NTDB provides information on patient injury and outcomes, it may not ofer detailed clinical insights into specifc treatments, interventions, or the infuence of comorbidities on the observed results. Another important limitation of this study is the lack of longitudinal data within NTDB. Terefore, relying solely on available NTDB data may not fully capture the long-term implications and outcomes related to the injuries under investigation.

Implications.
Te results of this study suggest that the hospital proft status signifcantly afects mortality rates in patients with severe abdominal injuries involving damage to the abdominal aorta and inferior vena cava. Policymakers should examine the reasons for this relationship and fnd ways to improve outcomes in for-proft hospitals. Healthcare professionals should be educated to properly identify and manage patients with abdominal trauma to improve their outcomes. Further research on abdominal aortic and vena cava injuries should focus on several key areas to improve patient care. First, diferences in trauma center levels and case volumes, especially in for-proft hospitals, should be explored. Understanding how these factors afect patient outcomes can inform resource allocation, trauma center designation, and case management strategies to optimize care. Including diverse patient populations from various healthcare systems will also provide a broader understanding of the impact of outcomes in these cases. Tis will ensure that any intervention developed based on the fndings can beneft a wider range of patients with these abdominal injuries.

. Conclusions
Tis study examined the diferences between hospital types (proft and nonproft) and TS (community, nonteaching, and university) with respect to the pattern of intent and mechanisms of trauma, response time, LOS, vital signs, and death under care. Te national incidence of vascular injuries was 0.17% among all injured patients in NTDB in 2017. NFH had lower DUC. Te reason for this is uncertain; however, it could be related to better perioperative care, which allows more critically wounded patients to arrive alive at the hospital due to the crucial amount of expertise and facilities available at the hospital. Tis study answers several unsettled questions about the hospital status and trauma outcomes by analyzing race, age, vital signs, and mortality and encourages future studies to explore the impact of case volume and trauma center level on achieving better outcomes. Tis study highlights the need to improve outcomes in patients with abdominal trauma, especially in for-proft hospitals. Additional research on trauma center factors and diverse patient populations can help develop evidence-based guidelines to manage aortic and vena cava injuries and reduce mortality rates. Policy changes and education for healthcare professionals may also help to address the disparities identifed in this study.

Data Availability
Te data used to support the fndings of this study are available from the corresponding author upon request.

Conflicts of Interest
Te author declares that there are no conficts of interest. Table S1: demographic details of the entire study population. Table S2: vital signs and EMS response of the entire study population.