Validating the Functional Capacity Index as a measure of outcome following blunt multiple trauma.

BACKGROUND: The validity of the Functional Capacity Index (FCI) is evaluated by examining its distributional characteristics, its correlation with other well-known measures of outcome and its ability to discriminate among persons with injuries of varying type and severity. METHODS: A telephone survey which included the FCI and the SF-36 was administered 1 year post-injury to 1240 blunt trauma patients discharged from 12 trauma centers. A subsample of 656 patients also completed the Sickness Impact Profile (SIP) by mail. RESULTS: FCI scores correlated well with the physical health subscores of the SIP and SF-36. They also correlated well with self-reported change in health status and return to work. The FCI, when compared to either the SF-36 or the SIP, however, appears to discriminate better among patients according to the presence and severity of head trauma. CONCLUSIONS: While further testing of the FCI is needed, it holds promise as a preference based measure for assessing the physical impact of trauma.

Comparison of alternative methods for assessing injury severity based on anatomic descriptors.

BACKGROUND: There is mounting confusion as to which anatomic scoring systems can be used to adequately control for trauma case mix when predicting patient survival. METHODS: Several Abbreviated Injury Scale (AIS) and International Classification of Disease Clinical (ICD-9CM)-based methods of scoring severity were compared by using data from the Pennsylvania Trauma Outcome Study. By using a design dataset, the probability of survival was modeled as a function of each score or profile. Resulting coefficients were used to derive expected probabilities in a test dataset; expected and observed probabilities were then compared by using standard measures of discrimination and calibration. RESULTS: The modified Anatomic Profile, Anatomic Profile, and New Injury Severity Score outperformed the International Classification of Disease-based Injury Severity Score. This finding remains true when AIS values are obtained by means of a conversion from International Classification of Disease to AIS. CONCLUSION: Results support the integrity of the AIS and argue for its continued use in research and evaluation. The modified Anatomic Profile, Anatomic Profile, and New Injury Severity Score, however, should be used in preference to the Injury Severity Score as an overall measure of severity.

Automated coding of injuries from autopsy reports.

Medical examiners have a unique database about trauma victims, many, if not most, of whom died at the scene or in transit to a hospital and who, thus, never had their injuries documented by trauma surgeons and so never entered into a local or regional trauma registry. These trauma registries have assisted in assessing the magnitude of traumatic injuries in the community and in evaluating the community's emergency medical systems. Without information about those who are dead at the scene or who die in transit, these trauma registries are incomplete and the evaluations based on them inaccurate. The data about the 50% of trauma victims who never enter the medical system are lacking in these registries. Such information is present in the death investigation and autopsy reports in the various medical examiner/coroner offices in the country. To access this important information more easily in trauma registries, an expert computer system was developed. This pilot study presents the results of using that system to gather medical examiner data. Injury descriptions were abstracted from autopsy reports of 50 consecutive nonhospitalized persons fatally injured in Mobile County, Alabama and its environs. Injury descriptions for all cases were successfully coded in International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM) and the Abbreviated Injury Scale (AIS-90) by an expert system. For some cases the expert system "requested" and received clarifying information, all of which was present in the medical records. This research demonstrates the feasibility of gathering accurate and consistent information on the estimated 50% of trauma deaths who do not reach a hospital and who are not included in acute care registries. Without data on such patients, our evaluation of trauma systems is incomplete and resources directed at prevention and treatment may be misapplied.

Improved predictions from a severity characterization of trauma (ASCOT) over Trauma and Injury Severity Score (TRISS): results of an independent evaluation.

OBJECTIVE: In 1986, data from 25,000 major trauma outcome study patients were used to relate Trauma and Injury Severity Score (TRISS) values to survival probability. The resulting norms have been widely used. Motivated by TRISS limitations, A Severity Characterization of Trauma (ASCOT) was introduced in 1990. The objective of this study was to evaluate and compare TRISS and ASCOT probability predictions using carefully collected and independently reviewed data not used in the development of those norms. DESIGN: This was a prospective data collection for consecutive admissions to four level I trauma centers participating in a major trauma outcome study. MATERIALS AND METHODS: Data from 14,296 patients admitted to the four study sites between October 1987 through 1989 were used. The indices were evaluated using measures of discrimination (disparity, sensitivity, specificity, misclassification rate, and area under the receiver-operating characteristic curve) and calibration [Hosmer-Lemeshow goodness-of-fit statistic (H-L)]. MEASUREMENTS AND MAIN RESULTS: For blunt-injured adults, ASCOT has higher sensitivity than TRISS (69.3 vs. 64.3) and meets the criterion for model calibration (H-L statistic < 15.5) needed for accurate z and W scores. The TRISS does not meet the calibration criterion (H-L = 30.7). For adults with penetrating injury, ASCOT has a substantially lower H-L value than TRISS (20.3 vs. 138.4), but neither meets the criterion. Areas under TRISS and ASCOT ROC curves are not significantly different and exceed 0.91 for blunt-injured adults and 0.95 for adults with penetrating injury. For pediatric patients, TRISS and ASCOT sensitivities (near 77%) and areas under receiver-operating characteristic curves (both exceed 0.96) are comparable, and both models satisfy the H-L criterion. CONCLUSIONS: In this age of health care decisions influenced by outcome evaluations, ASCOT's more precise description of anatomic injury and its improved calibration with actual outcomes argue for its adoption as the standard method for outcome prediction.

Institution and per-surgeon volume versus survival outcome in Pennsylvania's trauma centers.

BACKGROUND: The American College of Surgeons recommends minimum patient volumes for trauma centers and surgeons. Those numbers, however, are largely based on results from studies of surgical (but not trauma) relationships between volume and outcome. METHODS: Using stepwise regression, relationships were sought between measures of patient volume per trauma center and per surgeon and ana severity-controlled measure of survival outcome (W). For significant z values, W is the number of additional (or fewer) survivors, per 100 patients treated, than expected from ASCOT norms. W = 0 when z is nonsignificant. Data are from patients admitted in 1988 and 1989 to accredited Pennsylvania trauma centers. RESULTS: The relationships found for all patients and for adult blunt-injured patients are W = 0.3312 + 0.0200 (NSER/SURG) and W = 0.3638 + 0.0248 (NBSER/SURG), respectively, where NSER/SURG is the number of seriously, injured patients treated annually per surgeon and NBSER/SURG is the number of adult patients with serious blunt injuries treated annually per surgeon. Serious injury was defined, using the Injury Severity Scale, as > = 13 or, using the Abbreviated Injury Scale, as a head injury of > = 3. The relationships explained 36% and 61% of the variance in W (R2 for all patients and adult blunt-injured patients, respectively. To achieve normative survival (W =0), 95% confidence intervals suggest that a trauma surgeon should treat at least 35 seriously injured patients per year and at least 28 adult patients with serious blunt injury annually. No volume-related variable was a significant contributor to predictions of W for adult patients with penetrating injuries or for pediatric patients. CONCLUSIONS: These results support the regionalization of trauma care by affirming that increased per-surgeon experience in the treatment of seriously injured patients is associated with improved outcomes and help define the minimum experience needed to achieve normative survival. Prospective study of the relationship between volume and survival and other outcomes is required.

Comparison of three measures of injury severity in children with traumatic brain injury.

Eighty-six traumatically brain-injured children aged 6 to 15 years who were consecutively admitted to a pediatric Level I trauma center were recruited for participation in the study. A comprehensive battery of behavioral, cognitive, communicative, social, motoric, and neurological tests was administered to the children from 12 to 36 months postinjury. The performance of three severity indices, the Glasgow Coma Scale (GCS), the ASCOT probability of survival, and the head injury component of the Anatomic Profile, was compared with respect to their association with long-term outcomes in five neurological domains, as assessed by linear regression models. The ASCOT probability of survival was correlated to test scores in all five domains. The GCS and the head injury component of the Anatomic Profile were each correlated to outcome in only one domain. The ASCOT probability of survival, which includes coded variables for the GCS, systolic blood pressure, and respiratory rates on admission, as well as a measure of multisystem anatomic injury, was the most sensitive indicator of head injury severity and was associated with outcomes beyond survival and death in this population. Probability of survival is a promising brain injury severity index that may be useful in efforts to assess new medical and rehabilitative therapies for children with traumatic brain injury.

American College of Surgeons audit filters: associations with patient outcome and resource utilization.

OBJECTIVE: To determine if trauma patients qualifying by a 1990 American College of Surgeons (ACS) audit filter have the same outcomes and resource utilizations as similar (matching) patients not qualifying by the filter. DESIGN: Retrospective, case control study. MATERIALS AND METHODS: Data for 21,175 patients submitted during 1992 to the Pennsylvania Trauma Outcome Study (PTOS) were analyzed. Patients qualifying by each 1990 ACS audit filter were identified, except filters 13 and 22 that were not accommodated by the PTOS form. In addition, qualifiers by filter 21 (trauma deaths) were not analyzed. For each qualifier by a filter, matching patients who were not qualifiers by the filter were identified. Matching patients had the same cause of injury, A Severity Characterization of Trauma (ASCOT) age category, distribution of serious (Abbreviated Injury Score of > 2) injuries, intubation status, and coded Revised Trauma Score values on Emergency Department arrival. Qualifiers and matching patients were compared for their survival (z and W statistics), discharge disability (PTOS-Functional Independence Measure), and lengths of stay in the hospital (H-LOS) and in the Intensive Care Unit (ICU-LOS). MEASUREMENTS AND MAIN RESULTS: More than 57% of the study sample qualified by one or more filters. Filters 10 and 12 did not have sufficient qualifiers for evaluation. No filter's qualifiers were associated with significantly more disability at discharge than matching patients. The most frequently occurring filters (4, 2, and 5, respec-tively) deal with documentation deficiencies, but were not associated with significant results. Qualifiers by the nine filters below were associated with significantly greater mortality or H-LOS or ICU-LOS. [table: see text] CONCLUSIONS: Additional studies of the efficacy and efficiency of trauma quality assurance filters are needed. Objective criteria should be established for the definition, evaluation, modification, and adoption of trauma audit filters.

Comparison of mortality, morbidity, and severity of 59,713 head injured patients with 114,447 patients with extracranial injuries.

An analysis of the completed Major Trauma Outcome Study (MTOS) data set was undertaken to compare the incidence, mortality, morbidity, and injury severity of patients with head injuries (HI) with those of patients with extracranial injuries (ECI). The MTOS was completed recently after data from 174,160 patients submitted from 165 trauma centers from 1982 through 1989 were collated and validated. Data were analyzed with regard to the effect of injury causation for vehicular-related, nonvehicular-related, and penetrating injuries for patients with HI, ECI, or both. Detailed analyses of relationships between AIS-85 and Glasgow Coma Scale score from the entire data base, and between discharge status, functional independence measures (FIM scores), and severity of HI and ECI in a subset of 70,000 surviving patients were performed. Vehicular-related injuries (49.7%) were divided into those to vehicle occupants (36.4%), pedestrians (7.2%), and motorcyclists (6.0%). Nonvehicular-related blunt injuries included falls (18.4%) and assaults (13.2%) and penetrating injuries consisted of gunshots (8.7%), stabbings (8.0%), and other penetrations (1.8%). There were 59,713 patients with HI (34%) and 114,447 with no head injuries (NHI) (66%). Vehicular causes produced more HI (66.6%) than all other causes, despite the preponderance of nonvehicular-related HI in the overall series (50.3%). The overall MTOS mortality rate was 8.3%, but was three times higher in the HI group (14.5%) than in the NHI patients (5.1%). Injury severity measured by AIS-85 had, as expected, a profound influence on mortality of both HI and NHI groups. A similar high correlation was found between Glasgow Coma Scale score and mortality for head injured patients.(ABSTRACT TRUNCATED AT 250 WORDS)

An evaluation of expert human and automated Abbreviated Injury Scale and ICD-9-CM injury coding.

Two hundred ninety-five injury descriptions from 135 consecutive patients treated at a level-I trauma center were coded by three human coders (H1, H2, H3) and by TRI-CODE (T), a PC-based artificial intelligence software program. Two study coders are nationally recognized experts who teach AIS coding for its developers (the Association for the Advancement of Automotive Medicine); the third has 5 years experience in ICD and AIS coding. A "correct coding" (CC) was established for the study injury descriptions. Coding results were obtained for each coder relative to the CC. The correct ICD codes were selected in 96% of cases for H2, 92% for H1, 91% for T, and 86% for H3. The three human coders agreed on 222 (75%) injuries. The correct 7 digit AIS codes (six identifying digits and the severity digit) were selected in 93% of cases for H2, 87% for T, 77% for H3, and 73% for H1. The correct AIS severity codes (seventh digit only) were selected in 98.3% of cases for H2, 96.3% for T, 93.9% for H3, and 90.8% for H1. On the basis of the weighted kappa statistic TRI-CODE had excellent agreement with the correct coding (CC) of AIS severities. Each human coder had excellent agreement with CC and with TRI-CODE. Coders H1 and H2 were in excellent agreement. Coder H3 was in good agreement with H1 and H2. However, errors among the human coders often occur for different codes, accentuating the variability.(ABSTRACT TRUNCATED AT 250 WORDS)

Status of trauma patient management as measured by survival/death outcomes: looking toward the 21st century.

Since the focus of trauma care is to improve survival and norms have been established through large database studies to evaluate outcomes, the Relative Outcome Score provides a method to gauge treatment outcomes against perfection, on an ongoing basis, as long as baseline and severity mixes are standardized. The ROS will probably never reach 1.0 and may eventually plateau as treatment abilities are maximized for trauma patients, but the ROS does at least provide a measure to compare with the past, present and future.

Determining normative standards for functional independence measure transitions in rehabilitation.

We present a method for determination of normative standards for Functional Independence Measure (FIM) transitions in rehabilitation. Data from 230 consecutive brain-injured patients treated before 1991 were used to characterize transitions in patient FIM values between admission and discharge. The pre-1991 average and standard deviation FIM transitions, computed as a function of admission values, are used as standards ("norms") for comparing rehabilitation transitions among institutions or in one institution over time (say, yearly) and for identifying patients with striking transitions, believed worthy of audit. The evaluation method requires the computation of two statistics, z and W, which compare the actual transitions for patients of one time period (in this instance the 1991 patients) to the expected transitions as computed from the pre-1991 norms. The z and W values indicated that 1991 transitions were neither statistically nor clinically different from pre-1991 ones. Also introduced in the paper are the concepts of Mean Gain, Ideal Gain, and the ratio Mean Gain/Ideal Gain. Ideal Gain is the greatest possible "aggregated" transitions score for a study patient set and the ratio Mean Gain/Ideal Gain may be interpreted as "the degree of ideal rehabilitation transitions achieved."

Effect of preinjury illness on trauma patient survival outcome.

UNLABELLED: Data from 11,156 patients treated at the four Major Trauma Outcome Study controlled sites were used to estimate the effect on survival of each APACHE II preinjury illness condition (PIC). A case-control methodology was applied; 544 patients (4.8%) had one or more PICs. For each patient with a specific PIC we identified a set of matching patients with no PICs. A patient matches a PIC patient if both have the same mechanism of injury, the same coding of Revised Trauma Score variables (Glascow Coma Scale score, systolic blood pressure, respiratory rate), the same coded age per A Severity Characterization of Trauma) (ASCOT), and if they differ by no more than 0.5 for A, B, and C (the ASCOT components for serious injuries). The estimated survival probability for a PIC patient is either the survival rate for the patient's matched set or, if there are no matches, the patient's ASCOT survival probability. The survival probabilities were used to compare the actual and predicted numbers of survivors for each PIC, using z and W statistics. Computations of z and W were also made using ASCOT survival probabilities for each PIC patient. The results indicate profound effects of five PICs (hepatic, cardiovascular, respiratory, renal, diabetes) on trauma patient outcomes. CONCLUSION: Pre-existing organ dysfunction has a profound effect on patient outcome even after controlling for age, anatomic and physiologic severity, and mechanism of injury. But, because of their relatively low incidence in this sample, PICs did not strongly influence institutional outcome performance as measured by z and W values.

Pediatric coefficients for TRISS analysis.

We computed regression coefficients for TRISS analysis for all 4271 pediatric patients (aged 1 through 14 years) with complete data from the Major Trauma Outcome Study. We then compared predicted pediatric and adult TRISS survival probability norms. There were no statistically significant differences in the predicted and actual numbers of survivors using either norm. Differences in discrimination and reliability between the two norms were minimal. The study confirmed that the TRISS adult blunt norm is highly discriminating and reliable in predicting survival probabilities for pediatric patients. Given that both norms were equally good predictors, and the importance of a consistent system to evaluate trauma care, the authors recommend the continued use of the adult blunt trauma norm for estimating survival probability in children.

TRISS unexpected survivors--a statistical phenomenon or a clinical reality?

Data from patients treated in Pennsylvania-accredited trauma centers during 1989 were analyzed. TRISS expected and unexpected survivors (1.6% of all survivors) differed in many ways. Unexpected survivors were more than twice as likely to have been transferred from a nondesignated trauma center (45.8% vs. 22.8%, p < 0.001). Unexpected survivors had significantly higher frequencies of motor vehicle injuries (56.2% vs. 38.3%, p < 0.001), pedestrian injuries (9.6% vs. 5.4%, p < 0.01), and gunshot wounds (7.3% vs. 4.7%, p < 0.01). Expected survivors were injured more frequently in falls (26.1% vs. 10.8%, p < 0.001) and were less frequently male (64.5% vs. 75%, p < 0.001). Unexpected survivors had significantly longer average hospital stay (29.6 s vs. 9.3 days, p < 0.001) and more frequent (98.8% vs. 36.8%, p < 0.001) and longer average stays in the ICU (13.3 s vs. 4.1 days, p < 0.001). The percentage of unexpected survivors discharged to rehabilitation centers (61.9%) was significantly greater than that for expected survivors (8.7%), (p < 0.001). Unexpected survivors were more frequently judged "completely dependent" in five measures of functional disability than expected survivors. We conclude that unexpected survivors are a seriously injured and clinically relevant patient set, not just a statistical phenomenon.

Improvement in outcome from trauma center care.

Survival and death outcomes for patients with blunt injuries treated at one urban hospital were evaluated during a 6-year period of increasing commitment to trauma care, as evidenced by the construction of a resuscitation facility with integrated operating rooms. Patient survival, when controlled for severity mix, showed a trend of improvement during the study period. Improvement in survival outcome was more notable after the opening of the trauma resuscitation facility and among the more severely injured. When data from years 1 and 2 combined were compared with those from years 5 and 6, a statistically significant difference in survival was found, with an average of 13.44 more survivors per 100 patients treated per year with Injury Severity Scores greater than 15.

Bounds on a trauma outcome function via optimization.

One measure of the effectiveness of institutional trauma and burn management based on collected patient data involves the computation of a standard normal Z statistic. A potential weakness of the measure arises from incomplete patient data. In this paper, we apply methods of fractional programming and global optimization to efficiently calculate bounds on the computed effectiveness of an institution. The measure of effectiveness (i.e., the trauma outcome function) is briefly described, the optimization problems associated with its upper and lower bounds are defined and characterized, and appropriate solution procedures are developed. We solve an example problem to illustrate the method.

The effect of patient age upon survival in pediatric trauma.

Developmental changes in the anatomy and physiology of growing children are thought to improve the survivability of older children to significant injury. The effect of age upon survival, however, is poorly defined. Data for 4,615 patients less than 15 years old from a statewide trauma center registry were analyzed. Injury and survival were characterized by Abbreviated Injury Scale (AIS, 1985 revision), Injury Severity Score (ISS), Revised Trauma Score (RTS), and probability of survival [P(s)] and Z by TRISS. Patients were separated into age groups of 0 through 4, 5 through 9, and 10 through 14 years. The survival rate for patients with a maximum AIS 3 for any region was significantly higher in the 10-14-year age group. There were no significant differences in survival rates from head, thoracic, and abdominal injuries stratified by AIS among the three age groups. Survival rates for ISS cohorts were consistently lowest in the 0-4-year age group, but differences failed to reach significance. Survival for RTS and P(s) intervals were similar for all ages. The Z statistic reached significance for all children (Z = 4.717, W = 1.049), and for each group (Z = 2.203-3.029). Corresponding values of the W statistic suggest approximately one additional unexpected survivor per 100 admitted children when compared with the Major Trauma Outcome Study. Logistic regression for patients with all data required for TRISS showed no significant effect for any of the three age groups. We conclude that for this patient set, survival after childhood injury is independent of the age groups used in this study, after controlling for injury severity.

The Major Trauma Outcome Study: establishing national norms for trauma care.

The Major Trauma Outcome Study (MTOS) is a retrospective descriptive study of injury severity and outcome coordinated through the American College of Surgeons' Committee on Trauma. From 1982 through 1987, 139 North American hospitals submitted demographic, etiologic, injury severity, and outcome data for 80,544 trauma patients. Motor vehicle related injuries were most frequent (34.7%). Twenty-one per cent of patients had penetrating injuries. The overall mortality rate was 9.0%. The mortality rate for direct admissions was strongly related to the presence of serious head injury, 5.0% and 40.0%, when head injuries were less than or equal to AIS (Abbreviated Injury Scale) 3 or greater than or equal to AIS 4, respectively. Survival probability norms use the Revised Trauma Score, Injury Severity Score, patient age, and injury mechanism. Patients with unexpected outcomes were identified and statistical comparisons of actual and expected numbers of survivors made for each institution. Results provide a description of injury and outcome and support evaluation and quality assurance activities.

Progress in characterizing anatomic injury.

A three-valued description of anatomic injury is presented. Anatomic profile (AP) components A, B, and C summarize serious injuries (greater than AIS 2) to the head/brain or spinal cord; to the thorax or front of the neck; and all remaining serious injuries. Relationships between AP components and survival rate reaffirm the seriousness of head injury. Logistic function models relating AP components and the Injury Severity Score (ISS) to survival probability were based on 20,946 Major Trauma Outcome Study (MTOS) patients (9.2% mortality rate) submitted through 1986. Model performance comparisons were based on 5,939 MTOS patients (7.8% mortality rate) submitted during 1987. The AP better discriminated survivors from nonsurvivors and provided a 31% increase in sensitivity when compared with the ISS. Neither the ISS nor the AP alone reliably predict patient outcome. The predictive power of methods for estimating patient survival probability which include physiologic indices or profiles, patient age, and an anatomic profile should be compared with current methods. The AP, which is based on the severity and location of all serious injuries, provides a more rational basis for comparing patient samples than the ISS.