Stephen DiRusso

Traumatic brain injury in the elderly: Increased mortality and worse functional outcome at discharge despite lower injury severity

OBJECTIVE The purpose of this study was to compare data obtained from a statewide data set for elderly patients (age > 64 years) that presented with traumatic brain injury with data from nonelderly patients (age > 15 and < 65 years) with similar injuries. METHODS The New York State Trauma Registry from January 1994 through December 1995, from trauma centers and community hospitals excluding New York City (45,982 patients), was examined. Head-injured patients were identified by International Classification of Diseases, Ninth Revision diagnosis codes. A relative head injury severity scale (RHISS) was constructed on the basis of groups of these codes (range, 0 = none to 3 = severe). Comparisons were made with nonelderly patients for mortality, Glasgow Coma Scale (GCS) score at admission and discharge, Injury Severity Score, New Injury Severity Score, and RHISS. Outcome was assessed by a Functional Independence Measure score in three major domains: expression, locomotion, and feeding. Data were analyzed by the chi2 test and Mann-Whitney U test, with p < 0.05 considered significant. RESULTS There were 11,772 patients with International Classification of Diseases, Ninth Revision diagnosis of head injury, of which 3,244 (27%) were elderly. There were more male subjects in the nonelderly population (78% male subjects) compared with the elderly population (50% men). Mortality was 24.0% in the elderly population compared with 12.8% in the nonelderly population (risk ratio, 2.2; 95% confidence interval, 1.99-2.43). The elderly nonsurvivors were statistically older, and mortality rate increased with age. Stratified by GCS score, there was a higher percentage of nonsurvivors in the elderly population, even in the group with only moderately depressed GCS score (GCS score of 13-15; risk ratio, 7.8; 95% confidence interval, 6.1-9.9 for elderly vs. nonelderly). Functional outcome in all three domains was significantly worse in the elderly survivors compared with the nonelderly survivors. CONCLUSION Elderly traumatic brain injury patients have a worse mortality and functional outcome than nonelderly patients who present with head injury even though their head injury and overall injuries are seemingly less severe.

Predicting hospital mortality for patients in the intensive care unit: a comparison of artificial neural networks with logistic regression models.

ObjectiveLogistic regression (LR), commonly used for hospital mortality prediction, has limitations. Artificial neural networks (ANNs) have been proposed as an alternative. We compared the performance of these approaches by using stepwise reductions in sample size. DesignProspective cohort study. SettingSeven intensive care units (ICU) at one tertiary care center. PatientsPatients were 1,647 ICU admissions for whom first-day Acute Physiology and Chronic Health Evaluation III variables were collected. InterventionsNone. Measurements and Main Results We constructed LR and ANN models on a random set of 1,200 admissions (development set) and used the remaining 447 as the validation set. We repeated model construction on progressively smaller development sets (800, 400, and 200 admissions) and retested on the original validation set (n = 447). For each development set, we constructed models from two LR and two ANN architectures, organizing the independent variables differently. With the 1,200-admission development set, all models had good fit and discrimination on the validation set, where fit was assessed by the Hosmer-Lemeshow C statistic (range, 10.6–15.3;p ≥ .05) and standardized mortality ratio (SMR) (range, 0.93 [95% confidence interval, 0.79–1.15] to 1.09 [95% confidence interval, 0.89–1.38]), and discrimination was assessed by the area under the receiver operating characteristic curve (range, 0.80–0.84). As development set sample size decreased, model performance on the validation set deteriorated rapidly, although the ANNs retained marginally better fit at 800 (best C statistic was 26.3 [p = .0009] and 13.1 [p = .11] for the LR and ANN models). Below 800, fit was poor with both approaches, with high C statistics (ranging from 22.8 [p < .004] to 633 [p < .0001]) and highly biased SMRs (seven of the eight models below 800 had SMRs of <0.85, with an upper confidence interval of <1). Discrimination ranged from 0.74 to 0.84 below 800. ConclusionsWhen sample size is adequate, LR and ANN models have similar performance. However, development sets of ≤800 were generally inadequate. This is concerning, given typical sample sizes used for individual ICU mortality prediction.

Intubation of Pediatric Trauma Patients in the Field: Predictor of Negative Outcome Despite Risk Stratification

BACKGROUND Recently, evidence has shown that intubation in the field may not improve or may even adversely affect outcomes. Our objective was to analyze outcomes in pediatric intubated trauma patients using a large national pediatric trauma registry. METHODS The patient population was derived from the last phase of the National Pediatric Trauma Registry, comprising admissions from 1994 through 2002. Intubated patients were identified, as was their place of intubation: in the field, at a hospital that was not a trauma center, and at a trauma center. Risk stratification was performed for mortality using logistic regression models and variables available at presentation to the emergency room. Odds ratio and variable significance were calculated from the logistic regression model. The percentage of patients discharged to home and an abnormal Functional Independence Measure at hospital discharge examined functional outcome of survivors. RESULTS There were a total of 50,199 patients, 5460 (11.6%) of whom were intubated (1,930 in the field, 1,654 in the hospital, and 1,876 in a trauma center). Unadjusted mortality rates for intubated patients were as follows: field, 38.5%; hospital, 16.7%; and trauma center, 13.2% (all different, p < 0.05). The developed logistic regression model had an area under the receiver operating characteristic curve of 0.98. Compared with nonintubated patients, the odds ratio for field intubation, for non-trauma center, and for trauma center intubation was 14.4, 5.8, and 4.8, respectively (significantly different field vs. either hospital). The actual (observed) death rate was significantly higher than predicted in those intubated in the field. Stratification of injury by New Injury Severity Score or degree of head injury showed that this difference extended from mild to severe (e.g., odds ratio for New Injury Severity Score < 15 field vs. trauma center intubation, 12.3; odds ratio for none or moderate head injury, 5.1). Similar results were obtained for functional outcome in the survivors. CONCLUSION Field intubation is an independent strong negative predictor of survival or good functional outcome despite adjustment for severity of injury. Although not causal, the magnitude of these differences should lead to future controlled studies of pediatric trauma field intubations.

Preparation and achievement of American College of Surgeons level I trauma verification raises hospital performance and improves patient outcome.

OBJECTIVE The purpose of this study was to assess the impact on patient outcome and hospital performance of preparing for and achieving American College of Surgeons (ACS) Level I trauma verification. METHODS The center was a previously designated state regional trauma center located adjacent to a major metropolitan area. Preparation for ACS verification began in early 1996 and was completed in early 1998. Final verification took place in April 1999. Data were analyzed before (1994) and after (1998) the process. There was a marked increase in administrative support with trauma named one of the hospitals six centers of excellence. Two full-time board-certified trauma/critical care surgeons were added to the current six trauma surgeons. Their major focus was trauma care. Trauma support staff was also increased with case managers, a trauma nurse practitioner, additional trauma registrars, and administrative support staff. Education and continuous quality improvement were markedly expanded starting in 1996. RESULTS There were 1,098 trauma patients admitted in 1994, and 1,658 in 1998. Overall mortality decreased (1994, 7.38%; 1998, 5.37%; p < 0.05). There was a marked decrease in mortality for severely injured (Injury Severity Score > 30) patients (1994, 44% mortality [38 of 86]; 1998, 27% [22 of 80]; p < 0.04). Average length of stay also decreased (1994, 12.22 days; 1998, 9.87 days; p < 0.02). This yielded an estimated cost savings for 1998 of greater than

Prediction of mortality in pediatric trauma patients: new injury severity score outperforms injury severity score in the severely injured.

4,000 per patient (total saving estimate of

Survival in patients with severe adult respiratory distress syndrome treated with high-level positive end-expiratory pressure.

7.4 million). CONCLUSION Trauma system improvement as related to achieving ACS Level I verification appeared to have a positive impact on survival and patient care. There were cost savings realized that helped alleviate the added expense of this system improvement. The process of achieving ACS Level I verification is worthwhile and can be cost effective.

An artificial neural network as a model for prediction of survival in trauma patients: validation for a regional trauma area.

BACKGROUND The Injury Severity Score (ISS) is a widely accepted method of measuring severity of traumatic injury. A modification has been proposed--the New Injury Severity Score (NISS). This has been shown to predict mortality better in adult trauma patients, but it had no predictive benefit in pediatric patients. The aim of this study was to determine whether the NISS outperforms the ISS in a large pediatric trauma population. METHODS Admissions in the National Pediatric Trauma Registry between April 1996 and September 1999 were included. The ISS and NISS were calculated for each patient. The study endpoints were mortality at hospital discharge, functional outcome in three domains (expression, locomotion, and feeding), and discharge disposition for the survivors. Predictive ability of each score was assessed by area under the receiver operating characteristic curve. RESULTS The NISS and ISS performed equally well at predicting mortality in patients with lower injury severity (ISS < 25), but the NISS was significantly better at predicting mortality in the more severely injured patients. Both scores performed equally well at predicting expression and feeding ability. The NISS was superior to the ISS in predicting locomotion ability at discharge. Thirty-seven percent of patients had an NISS that was higher than their ISS. These patients had a significantly higher mortality and suffered worse functional outcomes. CONCLUSION The NISS performs as well as the ISS in pediatric patients with lower injury severity and outperforms the ISS in those with higher injury severity.

Mortality risk after head injury increases at 30 years

OBJECTIVE To assess the mortality rate and complications in a population of surgical patients with severe adult respiratory distress syndrome (ARDS) treated with positive end-expiratory pressure (PEEP) of > 15 cm H2O in an attempt to reduce intrapulmonary shunt to approximately 0.20 and reduce FIO2 to < 0.50. DESIGN Retrospective review of patients treated by a standardized ventilatory support protocol at the time of their illness. SETTING A 24-bed surgical intensive care unit in a university medical center. PATIENTS All patients admitted to the surgical intensive care unit during a 34-month period who met the criteria for severe ARDS (Pao2 of < or = 70 torr [< or = 9.3 kPa] on an FIO2 of > or = 0.50, diffuse interstitial and/or alveolar infiltrates on chest radiograph, decreased lung compliance, no evidence of congestive heart failure, and a likely predisposing etiology) were evaluated. Patients treated with PEEP of > 15 cm H2O were selected for this review. INTERVENTIONS Patients were treated by a protocol to achieve oxygenation end points, which consisted of maintaining arterial oxyhemoglobin saturation (as determined by pulse oximetry of > or = 0.92), while reducing FIO2 to < 0.50 and decreasing intrapulmonary shunt fraction to < or = 0.20 by adding PEEP. With the exception of patients with suspected intracranial hypertension related to closed-head injury, low-rate intermittent mandatory ventilation was the primary mode of ventilation. Pressure-support ventilation was added, when needed, to improve patient comfort, enhance spontaneous tidal volume, or improve CO2 excretion. MEASUREMENTS AND MAIN RESULTS Eighty-six patients with severe ARDS were treated with a PEEP of > 15 cm H2O. Nineteen of these patients died early of severe closed-head injury or massive uncontrollable hemorrhage and were excluded from the evaluation. The remaining 67 patients had a mean Lung Injury Score of 3.3 during their treatment with high PEEP. Twenty (30%) of 67 patients died. Eight of the deaths occurred after decrease of ventilatory support and with acceptable blood gases. The other 12 patients who died had continued oxygenation deficits and received increased levels of ventilatory support at the time of death. Twenty-six (39%) of 67 patients had radiographic manifestations of barotrauma (pneumothorax, subcutaneous emphysema, etc.) related to their primary injuries or to complications related to central venous catheter placement. Seven (17%) of 41 patients developed clinical or radiographic signs of barotrauma while receiving high-level PEEP. The hemodynamic effects of increased airway pressure were managed with fluids and inotropic agents, when necessary, and did not limit the application of PEEP to reach the defined end point of treatment. CONCLUSIONS This subset of patients with severe ARDS treated with high-level PEEP had a mortality rate lower than those rates previously reported by other researchers using more conventional ventilatory support and resuscitation techniques. FIO2 may be significantly reduced and PaO2 may be maintained at acceptable values by decreasing intrapulmonary shunt fraction using high-level PEEP.

Assessing educational validity of the Morbidity and Mortality Conference: A pilot study

BACKGROUND To develop and validate an artificial neural network (ANN) for predicting survival of trauma patients based on standard prehospital variables, emergency room admission variables, and Injury Severity Score (ISS) using data derived from a regional area trauma system, and to compare this model with known trauma scoring systems. PATIENT POPULATION The study was composed of 10,609 patients admitted to 24 hospitals comprising a seven-county suburban/rural trauma region adjacent to a major metropolitan area. The data was generated as part of the New York State trauma registry. Study period was from January 1993 through December 1996 (1993-1994: 5,168 patients; 1995: 2,768 patients; 1996: 2,673 patients). METHODS A standard feed-forward back-propagation neural network was developed using Glasgow Coma Scale, systolic blood pressure, heart rate, respiratory rate, temperature, hematocrit, age, sex, intubation status, ICD-9-CM Injury E-code, and ISS as input variables. The network had a single layer of hidden nodes. Initial network development of the model was performed on the 1993-1994 data. Subsequent models were generated using the 1993, 1994, and 1995 data. The model was tested first on the 1995 and then on the 1996 data. The ANN model was tested against Trauma and Injury Severity Score (TRISS) and ISS using the receiver operator characteristic (ROC) area under the curve [ROC-A(z)], Lemeshow-Hosmer C-statistic, and calibration curves. RESULTS The ANN showed good clustering of the data, with good separation of nonsurvivors and survivors. The ROCA(z) was 0.912 for the ANN, 0.895 for TRISS, and 0.766 for ISS. The ANN exceeded TRISS with respect to calibration (Lemeshow-Hosmer C-statistic: 7.4 for ANN; 17.1 for TRISS). The prediction of survivors was good for both models. The ANN exceeded TRISS in nonsurvivor prediction. CONCLUSION An ANN developed for trauma patients using prehospital, emergency room admission data, and ISS gave good prediction of survival. It was accurate and had excellent calibration. This study expands our previous results developed at a single Level I trauma center and shows that an ANN model for predicting trauma deaths can be applied across hospitals with good results

Mechanism of injury predicts case fatality and functional outcomes in pediatric trauma patients: The case for its use in trauma outcomes studies

BACKGROUND Age has long been recognized as a critical factor in predicting outcomes after head injury, with individuals older than 60 years predicted to have a worse outcome than those younger than 60. The object of this study was to determine the effect of age by decade of life beginning at birth in patients with head injuries of all levels of severity. STUDY DESIGN The New York State Trauma Registry was searched for head injuries from January 1, 1994 to December 31, 1995; the 13,908 cases found were placed into age groups by decade. Data were sought for each patient on demographics, Glasgow Coma Score, ICD-9 injury code, New Injury Severity Score (NISS), and mechanism of injury. These data were analyzed with chi-square and one-way ANOVA tests, with significance set at p < 0.05. RESULTS The risk of dying was significantly increased in patients beginning at 30 years of age compared with those in the younger age groups, with the greatest increases occurring after age 60 (p < 0.001). For the population with available Glasgow Coma Score data (n = 12,844), the mortality rate for patients ages 0 to 30 was 10.9%, and for patients ages 31 to 50 was 12.4%. The mean Glasgow Coma Score for nonsurvivors ages 0 to 20 (3.9) and for nonsurvivors ages 31 to 50 (5.1) were significantly different, with a risk ratio of 1.3 (p < 0.001). CONCLUSIONS The risk of dying for patients suffering head injuries increases as early as 30 years of age, making it necessary for health-care providers to consider increased monitoring and treatment for patients in this younger age group.