BACKGROUND: Several studies in the literature have examined the volume-outcome relationship for trauma, but the findings have been mixed, and the associated impact of the trauma center level has not been examined to date. The purposes of this study are to (1) determine whether there is a significant relationship between the annual volume of trauma inpatients treated in a trauma center (with "patients" defined in multiple ways) and short-term mortality of those patients, and (2) examine the impact on the volume-mortality relationship of being a Level I versus Level II trauma center.
METHODS: Data from New York's Trauma Registry in 2003 to 2006 were used to examine the impact of total trauma patient volume and volume of patients with Injury Severity Score (ISS) of at least 16 on in-hospital mortality rates after adjusting for numerous risk factors that have been demonstrated to be associated with mortality.
RESULTS: The adjusted odds of in-hospital mortality patients in centers with a mean annual volume of less than 2,000 patients was significantly higher (adjusted odds ratio = 1.46, 95% confidence interval, 1.25-1.71) than the odds for patients in higher volume centers. The adjusted odds of mortality for patients in centers with an American College of Surgeons-recommended annual volume of less than 240 patients with an ISS of at least 16 was 1.41 times as high (95% confidence interval, 1.17-1.69) as the odds for patients in higher volume centers. However, for both volume cohorts analyzed, the variation in risk-adjusted in-hospital mortality rate was greater among centers within each volume subset than between these volume subsets.
CONCLUSION: When considering the trauma system as a whole, higher total annual trauma center volume (2,000 or higher) and higher volume of patients with ISS ≥16 (240 and higher) are significant predictors of lower in-hospital mortality. Although the American College of Surgeons-recommended 1,200 total volume is not a significant predictor, hospitals in New York with ISS ≥16 volumes in excess of 240 also have total volumes in excess of 2,000. However, when considering individual trauma centers, high volume centers do not consistently perform better than low volume centers. Thus, despite the association between volume and mortality, we believe that the most accurate way to assess trauma center performance is through the use of an accurate, complete, comprehensive database for computing center-specific risk-adjusted mortality rates, rather than volume per se.
BACKGROUND: Previous studies of the center volume-outcomes relationship for severe trauma care have yielded conflicting findings regarding the presence or nature of such a relationship. Few studies have confined their analysis to Level I centers.
METHODS: We performed a retrospective analysis of severely injured adults treated from 2001 through 2006 in United States Level I trauma centers using data from the National Trauma Data Bank version 7.1. The post-injury in-hospital mortality rates for patients treated at high- or medium-volume Level I trauma centers were compared with the rates for patients treated at low-volume Level I centers before and after adjustment for patient demographic and injury characteristics. Subgroup comparisons were performed for those Level I centers with and without American College of Surgeons (ACS) verification of Level I designation.
RESULTS: Overall, medium-volume Level I trauma centers had significantly lower mortality than low-volume centers (14.3% versus 15.6%), both before and after adjustment for patient demographic and injury characteristics. Of those trauma centers without ACS verification of Level I designation, high-volume centers had significantly greater mortality than low-volume centers.
CONCLUSIONS: Our findings support the current utilization by the American College of Surgeons of minimum annual volume requirements for the verification of Level I trauma center designation, and suggest that the presence of such verification may enable Level I centers to effectively manage high volume of severely injured adult patients.
OBJECTIVE: The objective of this study was to investigate the effect of American College of Surgeons (ACS) trauma center designation and trauma volume on outcome in patients with specific severe injuries.
BACKGROUND: Trauma centers are designated by the ACS into different levels on the basis of resources, trauma volume, and educational and research commitment. The criteria for trauma center designation are arbitrary and have never been validated.
METHODS: The National Trauma Data Bank study, which included patients >14 years of age and had injury severity score (ISS) >15, were alive on admission and had at least one of the following severe injuries: aortic, vena cava, iliac vessels, cardiac, grade IV/V liver injuries, quadriplegia, or complex pelvic fractures. Outcomes (mortality, intensive care unit stay, and severe disability at discharge) were compared among level I and II trauma centers and between centers within the same level designation but different volumes of severe trauma (<240 vs > or =240 trauma admissions with ISS >15 per year). The outcomes were adjusted for age (<65 > or =65), gender, mechanism of injury, hypotension on admission, and ISS (< or =25 and >25).
RESULTS: A total of 12,254 patients met the inclusion criteria. Overall, level I centers had significantly lower mortality (25.3% vs 29.3%; adjusted odds ratio [OR], 0.81; 95% confidence interval [CI], 0.71-0.94; P = 0.004) and significantly lower severe disability at discharge (20.3% vs 33.8%, adjusted OR, 0.55; 95% CI, 0.44-0.69; P < 0.001) than level II centers. Subgroup analysis showed that cardiovascular injuries (N = 2004) and grades IV-V liver injuries (N = 1415) had a significantly better survival in level I than level II trauma centers (adjusted P = 0.017 and 0.023, respectively). Overall, there was a significantly better functional outcome in level I centers (adjusted P < 0.001). Subgroup analysis showed level I centers had significantly better functional outcomes in complex pelvic fractures (P < 0.001) and a trend toward better outcomes in the rest of the subgroups. The volume of trauma admissions with ISS >15 (<240 vs > or =240 cases per year) had no effect on outcome in either level I or II centers.
CONCLUSIONS: Level I trauma centers have better outcomes than lower-level centers in patients with specific injuries associated with high mortality and poor functional outcomes. The volume of major trauma admissions does not influence outcome in either level I or II centers. These findings may have significant implications in the planning of trauma systems and the billing of services according to level of accreditation.
BACKGROUND: Regionalization of trauma care services aims to improve outcomes by limiting trauma care delivery to a select group of dedicated trauma centers. However, the evidence linking trauma center volume and outcome is not conclusive. The objective of this study was to examine the volume-mortality relation for patients with severe trauma in the National Trauma Databank.
METHODS: This study was based on data for adult patients 18 years of age or older in the National Trauma Databank with an Injury Severity Score (ISS) of 15 or more who sustained either blunt or penetrating trauma. The main outcome measure was in-hospital survival as a function of trauma center volume. Logistic regression modeling was used to analyze the relation between survival and hospital volume for patients sustaining either severe blunt or severe penetrating trauma.
RESULTS: For the blunt trauma cohort, model diagnostics showed that the single highest-volume center was an outlier. After exclusion of the patients from this center, no association could be demonstrated between trauma volume and outcome (p = 0.465) for blunt trauma. A separate multivariate analysis of patients with penetrating trauma also could not demonstrate a significant volume-mortality association (p = 0.919). Both regression models exhibited excellent discrimination and acceptable calibration.
CONCLUSION: The findings of this study do not support the position that higher trauma center volumes are associated with improved survival. The implication of this study is that the hospital volume criteria established by the American College of Surgeons may need to be reexamined.
OBJECTIVE: Previous research assessing the impact of between-hospital trauma volume (high volume centers vs. low volume centers) and outcomes has been inconsistent. Furthermore, previous research has not considered temporal variations in within-hospital volume (a center having higher than average volume vs. lower than average volume) as a covariate. The objective of this study was to determine the relationship of between-hospital and within-hospital trauma volume and two measures of hospital quality of care.
DESIGN: Multivariable, hierarchical, mixed effects, logistic regression analyses of a population-based nonconcurrent cohort from 1995 to 1999.
SETTING: Thirty-nine nonfederal California hospitals included in the California Patient Discharge Data Set designated by local Emergency Medical Services authorities as adult trauma centers.
PATIENTS: All nonelderly adult trauma patients, 16-64 yrs (n = 54,352), and elderly adult trauma patients, >65 yrs (n = 47,656), admitted with an Injury Severity Score >9.
INTERVENTIONS: None.
MEASUREMENTS AND MAIN RESULTS: Severity adjusted in-hospital mortality rate and 30-day trauma-related readmissions were analyzed. Among nonelderly adult patients, higher annual between-hospital trauma volume was not associated with mortality rate (odds ratio, 1.02 for each 100 admissions; 95% confidence interval, 0.99, 1.06) but was associated with higher risk of readmission (odds ratio, 1.19 for each 100 admissions; 95% confidence interval, 1.13, 1.26). Among elderly adult patients, higher annual between-hospital trauma volume was associated with lower mortality (odds ratio, 0.79 for each 100 admissions; 95% confidence interval, 0.71, 0.87) but was not associated with risk of readmission (odds ratio, 0.96 for each 100 admissions; 95% confidence interval, 0.90, 1.04). Higher than average monthly within-hospital trauma volume was associated with higher odds of readmission (odds ratio, 1.11 for a volume deviation of ten patients per month; 95% confidence interval, 1.01, 1.21) among elderly adult patients.
CONCLUSIONS: The findings of this study in the context of previous research suggest that relationships between trauma volume and outcomes exist but depend on which patient populations are studied and how the data are analyzed. Furthermore, trauma centers may be subject to the detrimental effects of high temporal volume overextending existing services and capacity. Since this study found that both between-hospital volume and within-hospital volume measures are associated with outcomes, we recommend that both measures be included in future volume-outcome investigations.
BACKGROUND: The guidelines for Level I trauma center verification require 1,200 admissions per year. Several studies looking at the relationship between hospital volume and outcomes after injury have reached conflicting conclusions. The goal of our study was to examine the relationship between patient volume and outcomes (mortality and length of hospital stay) in California's trauma centers.
METHODS: Data for patients >or= 18 years old admitted after injury (n = 98,245) to a Level I or II trauma center (n = 38) in 1998 and 1999 were obtained from the Patient Discharge Data of the State of California. Hospital volume was derived from the annual number of admissions per center, and covariates including age, sex, mechanism of injury, Injury Severity Score, and trauma center designation were analyzed.
RESULTS: Hospital volume was not a significant predictor of death or length of hospital stay. More severely injured patients appeared to have worse outcomes at the highest volume centers.
CONCLUSION: In our study, hospital volume was not a good proxy for outcome. Low-volume centers appeared to have outcomes that were comparable to centers with higher volumes. Perhaps institutional outcomes rather than volumes should be used as a criterion for trauma center verification.
BACKGROUND: Evidence suggests that trauma centers treating high volumes of severely injured patients produce lower mortality rates than those with low volumes. However, the effect of individual surgeons' trauma caseload on outcomes has not been studied. This study compares outcomes between high-volume (HV) trauma surgeons admitting many patients with high injury severity, and low-volume (LV) surgeons treating fewer critical patients per year.
METHODS: All trauma patients admitted to a large Level I trauma center over a 12-year period were assigned to either the HV or LV group, depending on the yearly volume of their admitting surgeon. Surgeons treating > 35 severely injured (Injury Severity Score > 15) patients per year were considered HV. Student's t test and chi2 analysis were used to test comparability of LV and HV patient groups and to compare mortality rates. Mortality rates of HV and LV surgeons' patients were compared in six injury patterns selected to represent moderate to severe injury. TRISS methodology (z score) was also used to assess outcomes in the two groups. The inherent bias of the TRISS method in comparing trauma outcomes was minimized by the homogeneity of the studied patient population.
RESULTS: A total of 16,481 patients were admitted to HV surgeons, and 4,214 patients were admitted to LV surgeons. In all subgroups, HV and LV patients were similar regarding age, sex, physiologic status at admission, injury pattern, and injury severity. Mortality rates for HV and LV surgeons were not significantly different between the two groups in any injury pattern. The z score was 1.88 in the HV patient group versus 0.47 in the LV group.
CONCLUSION: Within a single institution, mortality rates for patients treated by surgeons admitting many severely injured patients were not significantly different from low-volume surgeons' patients, although there was a trend toward higher mortality in the less active surgeons' patients in some subgroups.
BACKGROUND: The purpose of this study was to evaluate the impact of five trauma center characteristics on survival outcome in nine serious injury categories.
METHODS: A retrospective analysis of prospectively collected data from 1992 to 1996 on patients older than 14 years of age from 24 accredited trauma centers in Pennsylvania was performed. Trauma center characteristics selected for evaluation were level of accreditation, volume of trauma admissions, presence of in-house trauma surgeons, presence of a surgical residency program, and presence of an on-site medical school. Each of these characteristics was evaluated to determine its impact on survival in the selected serious injuries. A logistic regression model was then created to evaluate the most seriously injured patients as defined by A Severity Characterization of Trauma score of < 0.50. On the basis of the logistic regression model, odd ratios were calculated treating low volume as a significant risk factor for mortality.
RESULTS: Of the 88,723 patients meeting registry criteria, 13,942 met the serious injury criteria. Independent analysis suggested that accreditation was beneficial regardless of level, volume of patients treated had a direct impact on survival outcome, and the presence of a surgical residency program may confer survival benefit. Of the 13,942 patients with serious injuries, those with A Severity Characterization of Trauma score of < 0.5 were selected for evaluation by logistic regression (n = 3,562). The logistic regression model, however, showed that only volume of patients treated had a consistent association with improved survival. Odds ratio analysis revealed low volume as a significant risk factor for mortality in seven of the nine injuries studied.
CONCLUSION: In this analysis, only volume of patients treated had a direct impact on survival outcome. Accreditation, regardless of level, appears to be beneficial.
BACKGROUND: The 1999 American College of Surgeons resources for optimal care document added the requirement that Level I trauma centers admit over 240 patients with Injury Severity Score (ISS) > 15 per year or that trauma surgeons care for at least 35 patients per year. The purpose of this study was to test the hypothesis that high volume of patients with ISS > 15 per individual trauma surgeon is associated with improved outcome.
METHODS: Data were obtained from the trauma registry of the five American College of Surgeons-verified adult Level I trauma centers in our mature trauma system between January 1, 1998, and March 31, 1999. Data abstracted included age, sex, Glasgow Coma Scale (GCS) score, intensive care unit length of stay, hospital length of stay, probability of survival (Ps), mechanism of injury, number of patients per each trauma surgeon and institution, and mortality. Multiple logistic regression was performed to select independent variables for modeling of survival.
RESULTS: From the five Level I centers there were 11,932 trauma patients in this time interval; of these, 1,754 patients (14.7%) with ISS > 15 were identified and used for analysis. Patients with ISS > 15 varied from 173 to 625 per institution; trauma surgeons varied from 8 to 25 per institution; per-surgeon patient volume varied from 0.8 to 96 per year. Logistic regression analysis revealed that the best independent predictors of survival were Ps, GCS score, age, mechanism of injury, and institutional volume (p < 0.01). Age and institutional volume correlated negatively with survival. Analysis of per-surgeon patient caseload added no additional predictive value (p = 0.44).
CONCLUSION: The significant independent predictors of survival in severely injured trauma patients are Ps, GCS score, age, mechanism of injury, and institutional volume. We found no statistically meaningful contribution to the prediction of survival on the basis of per-surgeon patient volume. Since this volume criterion for surgeon enpanelment and trauma center designation would not be expected to improve outcome, such a requirement should be justified by other measures or abandoned.
CONTEXT: The premise underlying regionalization of trauma care is that larger volumes of trauma patients cared for in fewer institutions will lead to improved outcomes. However, whether a relationship exists between institutional volume and trauma outcomes remains unknown.
OBJECTIVE: To evaluate the association between trauma center volume and outcomes of trauma patients.
DESIGN: Retrospective cohort study.
SETTING: Thirty-one academic level I or level II trauma centers across the United States participating in the University Healthsystem Consortium Trauma Benchmarking Study.
PATIENTS: Consecutive patients with penetrating abdominal injury (PAI; n = 478) discharged between November 1, 1997, and July 31, 1998, or with multisystem blunt trauma (minimum of head injury and lower-extremity long-bone fractures; n = 541) discharged between June 1 and December 31, 1998.
MAIN OUTCOME MEASURES: Inpatient mortality and hospital length of stay (LOS), comparing high-volume (>650 trauma admissions/y) and low-volume (</=650 admissions/y) centers.
RESULTS: After multivariate adjustment for patient characteristics and injury severity, the relative odds of death was 0.02 (95% confidence interval [CI], 0.002-0.25) for patients with PAI admitted with shock to high-volume centers compared with low-volume centers. No benefit was evident in patients without shock (P =.50). The adjusted odds of death in patients with multisystem blunt trauma who presented with coma to a high-volume center was 0.49 (95% CI, 0.26-0.93) vs low-volume centers. No benefit was observed in patients without coma (P =.05). Additionally, a shorter LOS was observed in patients with PAI and New Injury Severity Scores of 16 or higher (difference in adjusted mean LOS, 1.6 days [95% CI, -1.5 to 4.7 days]) and in all patients with multisystem blunt trauma admitted to higher-volume centers (difference in adjusted mean LOS, 3.3 days [95% CI, 0.91-5.70 days]).
CONCLUSIONS: Our results indicate that a strong association exists between trauma center volume and outcomes, with significant improvements in mortality and LOS when volume exceeds 650 cases per year. These benefits are only evident in patients at high risk for adverse outcomes.
Several studies in the literature have examined the volume-outcome relationship for trauma, but the findings have been mixed, and the associated impact of the trauma center level has not been examined to date. The purposes of this study are to (1) determine whether there is a significant relationship between the annual volume of trauma inpatients treated in a trauma center (with "patients" defined in multiple ways) and short-term mortality of those patients, and (2) examine the impact on the volume-mortality relationship of being a Level I versus Level II trauma center.
METHODS:
Data from New York's Trauma Registry in 2003 to 2006 were used to examine the impact of total trauma patient volume and volume of patients with Injury Severity Score (ISS) of at least 16 on in-hospital mortality rates after adjusting for numerous risk factors that have been demonstrated to be associated with mortality.
RESULTS:
The adjusted odds of in-hospital mortality patients in centers with a mean annual volume of less than 2,000 patients was significantly higher (adjusted odds ratio = 1.46, 95% confidence interval, 1.25-1.71) than the odds for patients in higher volume centers. The adjusted odds of mortality for patients in centers with an American College of Surgeons-recommended annual volume of less than 240 patients with an ISS of at least 16 was 1.41 times as high (95% confidence interval, 1.17-1.69) as the odds for patients in higher volume centers. However, for both volume cohorts analyzed, the variation in risk-adjusted in-hospital mortality rate was greater among centers within each volume subset than between these volume subsets.
CONCLUSION:
When considering the trauma system as a whole, higher total annual trauma center volume (2,000 or higher) and higher volume of patients with ISS ≥16 (240 and higher) are significant predictors of lower in-hospital mortality. Although the American College of Surgeons-recommended 1,200 total volume is not a significant predictor, hospitals in New York with ISS ≥16 volumes in excess of 240 also have total volumes in excess of 2,000. However, when considering individual trauma centers, high volume centers do not consistently perform better than low volume centers. Thus, despite the association between volume and mortality, we believe that the most accurate way to assess trauma center performance is through the use of an accurate, complete, comprehensive database for computing center-specific risk-adjusted mortality rates, rather than volume per se.
