Injury scaling at autopsy: the comparison with premortem clinical data

The difference between injury scaling performed in the same patients on the basis of clinical information only and postmortem examination only is largely unknown. We compared scores in all 279 trauma patients who died in the Department of Critical Care Medicine at Auckland Hospital from 1982 through 1987 (93% blunt trauma, 4% penetrating trauma, 3% burns; median time until death--2 days) using both the 1980 and 1985 revisions of the Abbreviated Injury Scale (AIS-80, AIS-85) and derived Injury Severity Scores (ISS-80, ISS-85) where such scoring was based on clinical information only (CLAIS, CLISS) or postmortem findings only (PMAIS, PMISS). For the group as a whole, there was little difference in the distribution of scores between CLAIS and PMAIS or between CLISS and PMISS. However, CLISS-80 was different from PMISS-80 in 68% of individual patients. Most major differences between CLAIS and PMAIS (two AIS grades or more) occurred in the Head region, where injury scoring based on physiological features (e.g. coma) occurred without an anatomic injury of similar AIS grade, or in the Thorax region where therapy had either abolished the evidence of injury (e.g. pneumothorax) or injuries were discovered at postmortem examination which had not been appreciated clinically. Injury scaling data derived only from postmortem examination is not equivalent to that derived clinically. For maximum accuracy, postmortem data must be derived from an examination specifically guided by the needs of injury scaling and in full cognizance of injuries recognised and treated clinically.     

Injury severity scoring: a comparison of early clinical versus discharge diagnosis

The Abbreviated Injury Scale (AIS) and the Injury Severity Score (ISS) are objective means of assessing injury. Accepted methodology involves retrospective scoring of injury based on discharge diagnoses. Recently, early clinical scoring, supplemented by review at discharge, has been introduced. A prospective study was instituted to compare these methodologies. Four hundred sixty consecutive victims of blunt trauma were scored using both clinical and retrospective methodologies by independent, blinded observers. Of these, 333 patients had a change in ISS, 174 with a change of greater than four points. The population mean ISS remained unchanged; however, paired values were significantly different (p less than .03). We conclude that either methodology is applicable for studies of large populations of trauma victims. When accurate individual AIS or ISS scoring is required, the clinical method combined with discharge review is most appropriate.     

The abbreviated injury scale: Evolution,usage and future adaptability

Injury Scaling as a means for classifying the extent of trauma has a long histroy. This paper describes the origin, development and usage of the Abbreviated Injury Scale. Major revisions to AIS-80 are discussed in detail. Both the value of the AIS as a research tool and its limitations are presented. The critical need for training AIS users in proper application is addressed. The future role of the Committee on Injury Scaling is explained, and three potential uses of the AIS are suggested as priority items. The paper, accompanied by a comprehensive bibliography, serves as a basic state of the art reference for physicians and others researchers in the traffic medicine and highway safety field.     

The probability of death score: An improvement of the injury severity score

Two large sets of data containing information on the injuries and survival status of traffic accident casualties were used to develop a summary injury score from the Abbreviated Injury Scale (AIS). The summary injury score, dubbed the Probability of Death Score (PODS), was based on a logistic regression model of the two highest AIS codes taken from a 19-category coding scheme. A third large set of trauma data was used to compare the statistical performance of the PODS to that of the Injury Severity Score (ISS). Several measures of predictive accuracy and goodness of fit demonstrated the relative advantage of the PODS over the ISS in characterizing the association between injury and death.     

A system for measuring the severity of temporary and permanent disability after injury

500 patients have been questioned about activities of daily living and mobility 4 and 26 weeks after injury in order to assess the extent of temporary and permanent disability following minor and major trauma. Only those who sustained single injuries have been assessed, resulting in a relatively small number of serious injuries in the sample. In other respects, the population is representative of the daytime attendance at a busy emergency department. Most patients sustained injuries with an Abbreviated Injury Scale (AIS) of 1 or 2 (96%); it is clear that the AIS is unable to distinguish between most small injuries. Assessment was by interview. Although subjective, this has produced results that have face validity and discriminate between a wide variety of injuries. The methodology may be useful in the development of a "disability score," but much more data will be required before this can be achieved.     

Is the TMPM-ICD9 revolution in trauma risk-adjustment compatible with imperfect administrative coding?

BackgroundTMPM-ICD9 is the latest injury-severity measure based on empirical estimation from ICD-9-CM codes. It is candidate to replace expert-based AIS measures worldwide because of easier accessibility and better predictive performances. In Italy and other countries administrative ICD coding is generally less complete than dedicated AIS coding. We attempted to ascertain how this affects TMPM performances.MethodsDiscrimination (c statistics) and calibration (calibration curves, Akaike's criterion) of hierarchical logistic regression models for hospital mortality comprising TMPM or ISS were compared using trauma-registry data on 3570 patients of years 2007–2009. The completeness of AIS vs. ICD-9-CM coding was also investigated through the ratio of the respective numbers of codes per patient. Model discrimination was further analyzed after stratification according to the above ratio (>1 and ≤1).ResultsThe models with TMPM showed worse performances. The differences, concerned calibration (graphical evidence) in univariate models and discrimination (−1.2% of area under the ROC curve, p < 0.05) in models completed with age, gender, mechanism of injury, motor GCS and systolic pressure. In parallel, ICD coding was less complete than AIS, as expected: 68% of patients had a ratio >1. The discrimination of TMPM vs. ISS models improved when the ratio changed from >1 to ≤1.ConclusionsThe predictive performances of TMPM-ICD9 vs. ISS were lower than in the previous studies; the sub-optimal quality of ICD coding was a main cause. Imperfect administrative coding may hence hamper the TMPM-ICD9 revolution, although in our setting the negligible differences and the ready availability of administrative data may still give reason for adopting TMPM-ICD9.     

Is the TMPM-ICD9 revolution in trauma risk-adjustment compatible with imperfect administrative coding?

Background

TMPM-ICD9 is the latest injury-severity measure based on empirical estimation from ICD-9-CM codes. It is candidate to replace expert-based AIS measures worldwide because of easier accessibility and better predictive performances. In Italy and other countries administrative ICD coding is generally less complete than dedicated AIS coding. We attempted to ascertain how this affects TMPM performances.

Methods

Discrimination (c statistics) and calibration (calibration curves, Akaike's criterion) of hierarchical logistic regression models for hospital mortality comprising TMPM or ISS were compared using trauma-registry data on 3570 patients of years 2007–2009. The completeness of AIS vs. ICD-9-CM coding was also investigated through the ratio of the respective numbers of codes per patient. Model discrimination was further analyzed after stratification according to the above ratio (>1 and ≤1).

Results

The models with TMPM showed worse performances. The differences, concerned calibration (graphical evidence) in univariate models and discrimination (−1.2% of area under the ROC curve, p < 0.05) in models completed with age, gender, mechanism of injury, motor GCS and systolic pressure. In parallel, ICD coding was less complete than AIS, as expected: 68% of patients had a ratio >1. The discrimination of TMPM vs. ISS models improved when the ratio changed from >1 to ≤1.

Conclusions

The predictive performances of TMPM-ICD9 vs. ISS were lower than in the previous studies; the sub-optimal quality of ICD coding was a main cause. Imperfect administrative coding may hence hamper the TMPM-ICD9 revolution, although in our setting the negligible differences and the ready availability of administrative data may still give reason for adopting TMPM-ICD9.     

Injury severity of pedestrians,bicyclists and motorcyclists resulting from crashes with reversing cars

ObjectivePedestrians, bicyclists and motorcyclists can suffer serious injury in road traffic crashes. To date, no studies examine the injury severity within this vulnerable cohort following collisions with reversing cars.Material and methodsOur institution prospectively maintains a database including medical and technical information regarding traffic accidents in our area, including urban and suburban regions. In a retrospective review of this database, the authors describe the injury severity of pedestrians, bicyclists and motorcyclists following traffic crashes involving reversing cars. Injury severity was described using the abbreviated injury scale (AIS) as well as the maximum abbreviated injury scale (MAIS).ResultsThis study included 234 crashes occurring between 1999 and 2012. The lower extremity was injured most often while also suffering more severe injuries with a median AIS of 1 compared to 0 in all other documented body regions. The upper extremity was injured second most often. AIS ranging from 4 to 6 were infrequent. AIS 3 however, was documented for the legs in 4.3% of patients. MAIS 0, 1, 2, 3, 5 and 9 were found in 1, 164, 46, 14, 1, and 8 patients in the study cohort, respectively. Pedestrians and motorcyclists were seriously injured in 9.1% and 9.6% of cases, respectively. In contrast, no bicyclists suffered serious injuries. As to the zone of impact, most collisions occurred at the rear center of the vehicle (35%) followed by rear left (26%), rear right (20%), side rear (11%), side center (4%) and side front (3%). 204 (87.2%) collisions occurred during the day, 19 (8.1%) at night and 11 (4.7%) at twilight. Speed was similar in crashes involving pedestrians, bicyclists and motorcyclists, being as high as 7.0 ± 3.6, 7.0 ± 4.0 and 7.9 ± 4.2 km/h respectively.ConclusionsThis is the first study that analyzes injury severity among these vulnerable road users following collisions with reversing vehicles. The majority of collisions occur at low impact speed during the day. Most injuries resulting from these collisions are not serious, however pedestrians are at greatest risk of severe injury to any body region. The lower extremities suffer the most serious and frequent injuries within this cohort.     

Overweight children: Are they at increased risk for severe injury in motor vehicle collisions?

Background

Obesity is an epidemic in the United States. The relationship between traumatic injury and obesity in children is not well-studied. We hypothesized that overweight children suffer more severe injuries, different distributions of injuries and improper use of restraints in motor vehicle collisions.

Methods

We conducted a secondary analysis of the CIREN database of motor vehicle collisions of subjects 2-17 years old. Overweight was defined as a BMI percentile for age >85%. Significant injury was an Injury Severity Score (ISS) >15 or an Abbreviated Injury Scale (AIS) score greater than one. Further analysis looked at injuries classified as head, trunk, or extremities and appropriateness of restraints. Odds ratios compared the overweight to lean groups.

Results

335 subjects met inclusion criteria with 35.5% of cases being overweight. For significant injury, overweight cases had an odds ratio of 1.2 [95% CI: 0.8-1.9]. Analysis by AIS for overall significant injury and to specific body regions also did not show any significant associations. Overweight versus lean subjects had an odds ratio of 1.3 [95% CI: 0.8-2.1] for improper use of restraints.

Conclusions

We found no significant relationship between pediatric injury severity, distribution of injuries, or restraint use and being overweight. Limitations of this study were the small sample size in this database and the large number of unrestrained subjects.     

Factors affecting pelvic and thoracic forces in near-side impact crashes: a study of US-NCAP, NASS, and CIREN data

The goal of this study was to identify variables related to vehicle design which are associated with pelvic and thoracic accelerations as measured by the driver's (near side) crash dummy during new car assessment program (NCAP) testing of motor vehicles. Vehicle specific parameters were analyzed using NCAP side impact test results. Data from national automotive sampling system, crashworthiness data system (NASS-CDS) and crash injury research and engineering network (CIREN) (both National Highway Traffic Safety Administration (NHTSA) injury databases) were assessed to confirm NCAP test observations. In addition, door armrest stiffness measurements were performed using a mechanical tester on a sample of 40 vehicles. NCAP data showed that of 10 variables tested using multiple linear regression, vehicle weight and door crush correlated with pelvic acceleration of the driver's crash dummy (overall, r2=0.58, p=0.002, n=165). For thoracic trauma index (TTI) vehicle weight and peak door velocity correlated, significantly (overall, r2=0.41, p=0.03, n=165). Mean TTI was 63.7 g with no side airbag (n=108) and 55.6 g with a thoracic side airbag (n=54), p=0.01. The mean vehicle weight and door crush between airbag and no airbag groups were not significantly different. NASS-CDS data demonstrated a direct relationship between increased door crush and increased abbreviated injury score (AIS). CIREN data showed that occupants who sustained pelvic injuries had a median AIS of 3 with 24.9 cm of door crush, with abdominal injuries, a median AIS of 3 and 30 cm of crush, and with thoracic injuries, a median AIS of 4 and 34 cm of door crush. In addition, the frequency of bilateral pelvic injuries was significantly higher for subjects in CIREN crashes who were in a vehicle with a center console, but only if door intrusion was greater than 15 cm. This information may be useful in design of vehicles with greater protection in side impact crashes.     

Trends in helmet use and head injuries in San Diego County: the effect of bicycle helmet legislation

The purpose of this study is to evaluate the effect of California's bicycle helmet law on bicycle-related head injuries in San Diego County with a year 2000 population of approximately 3 million people. The study design is an ecological trend design based on observational data from a Trauma Registry. Outcome measures include helmet use compliance, site/severity of injury and abbreviated injury scale (AIS). There were 1116 bicycle trauma patients recorded in the San Diego County Trauma Registry between 1992 and 1996. The percentages of pre-law and post-law helmet use were 13.2 and 31.7%, respectively. Over the whole study period, the overall helmet use increased by an average of 43% per year with an averaged 84% rate increase in helmet use among children. Only 16.1% of patients with serious head injury used helmets, compared to 28.2% in those who did not have serious head injury. The odds ratio of helmet use against serious head injuries is 0.43 (95% CI 0.28-0.66) after adjusting for age, ethnicity and time. The p-values for comparing pre- and post-legislation serious head injury rates are p=0.764, 0.4 and 0.194 for the overall, adult and child populations, respectively. Helmet legislation increased helmet use in the targeted child population and the effect was carried over to the adult population. Helmet use has a protective effect against serious head injury. Probably due to several of its limitations, the current study did not confirm that helmet legislation alone significantly reduced head injury rates in San Diego County during the study period.     

The influence of vehicle damage on injury severity of drivers in head-on motor vehicle crashes

Data from crashes investigated through the Crash Injury Research and Engineering Network (CIREN) Program were used to assess differences in injury patterns, severity, and sources for drivers, protected by safety belts and deploying steering wheel air bags, in head-on frontal impacts. We studied whether exterior vehicle damage with a different distribution (wide vs. narrow) across the front vehicle plane influenced injury characteristics. Drivers from both impact types were similar on the basis of demographic characteristics (except age), restraint use, and vehicle characteristics. There were significant differences in the type of object contacted and intrusion into the passenger compartment at the driver's seat location. The mean delta V (based on the kilometers per hour change in velocity during the impact) was similar for drivers in both (wide vs. narrow) impact types. There were no significant differences in injury patterns and sources except that drivers in wide impacts were almost 4 times more likely (odds ratio (OR)=3.81, 95% confidence limits (CL) 1.26, 11.5) to have an abbreviated injury scale (AIS) 3 serious or greater severity head injury. Adjusted odds ratios showed that drivers in wide impacts were less likely (OR=0.54, 95% CI 0.37, 0.79) to have severe injury (based on injury severity score (ISS)>25) when controlling for intrusion, vehicle body type, vehicle curb weight, age, proper safety belt use, and delta V. Drivers with intrusion into their position or who were driving a passenger vehicle were almost twice more likely to have severe injury, regardless of whether the frontal plane damage distribution was wide or narrow. Our study supports that the type of damage distribution across the frontal plane may be an important crash characteristic to consider when studying drivers injured in head-on motor vehicle crashes.     

Sex and age distribution in transport-related injuries in Tehran

Intercountry or regional differences in patterns of injury by the road user type have significant implication for prevention policies. In order to have an estimate from the existing conditions of transport-related injuries (TRIs) and especially to evaluate sex and age distribution of traffic accident victims, we analyzed information of 8426 hospitalized trauma patients during 13 months of data gathering process. Forty-five percent of the injuries were related to car accidents and men/women ratio in these patients was 4.2/1. The highest men/women ratio was (16/1) for motorcyclists, while the lowest ratio (1/1), was for rear seat car passengers. Mean (+/-S.D.) age of the patients was 31 (+/-18), and men were nearly 2 years younger than women (33 versus 31). Sixty-seven percent of the females' and 44% of the males' injuries were related to pedestrian crashes. Motorcycle-related injuries in men and car passenger related injuries in women were the second most common type of crash (42 and 22%, respectively). The use of protective devices in our population was worrisome. In only 6% of the male motorcyclists helmet use was reported, and 3% of the male car occupants had used seatbelts at the time of the accident. The condition in the female population was much worse and no use of the protective devices was reported in this group of the patients. Crude mortality rate in men was nearly two times that of women (6.2% versus 3.8%). After adjustment for age, injury severity score (ISS) and category of the road users, men and women had similar mortality rate.     

Disabilities caused by road traffic accidents and their relation to severity scores

The disabilities incurred by 2502 road accident patients admitted in three separate years to an Accident Hospital have been analysed. There were about equal numbers of disabled among pedestrians, motorcyclists and vehicle occupants. This corresponds to the high relative frequency and severity of injuries among motorcyclists. Most of the serious disabilities were caused by head or lower limb injuries. Different severities of disability were not closely correlated with Abbreviated Injury Scale (AIS), (ISS) or (PI) scores or with treatment periods but useful threshold values are described which separate groups with high and low rates of disability. For given severities of injury, disabilities were less severe among young casualties. Comparisons with other studies show rather wide variations in estimates of the incidence of slight disabilities. There is fair agreement with the present findings that serious disabilities occur in about 3% of inpatient hospital cases or in about 1% of total casualties.     

Misclassification of injury severity among road casualties in police reports

This study aims to evaluate the discordance between police reports of injury severity among road casualties and the length of hospital stay and the Injury Severity Scale (ISS) by linking information from the crash records of the Hong Kong Police with the trauma records of a regional hospital. Sensitivity and specificity analyses suggest that police injury grading diverges noticeably from the definition of a 12-h hospital stay. Police reports overestimate injury severity remarkably. The results of logistic regression indicate that age, the ISS, and the position of the victim significantly determine the likelihood of police injury misclassification. Furthermore, an optimal demarcation point of the length of hospital stay for serious injury is estimated.     

Injury prediction in a side impact crash using human body model simulation

Background

Improved understanding of the occupant loading conditions in real world crashes is critical for injury prevention and new vehicle design. The purpose of this study was to develop a robust methodology to reconstruct injuries sustained in real world crashes using vehicle and human body finite element models.

Methods

A real world near-side impact crash was selected from the Crash Injury Research and Engineering Network (CIREN) database. An average sedan was struck at approximately the B-pillar with a 290 degree principal direction of force by a lightweight pickup truck, resulting in a maximum crush of 45 cm and a crash reconstruction derived Delta-V of 28 kph. The belted 73-year-old midsized female driver sustained severe thoracic injuries, serious brain injuries, moderate abdominal injuries, and no pelvic injury. Vehicle finite element models were selected to reconstruct the crash. The bullet vehicle parameters were heuristically optimized to match the crush profile of the simulated struck vehicle and the case vehicle. The Total Human Model for Safety (THUMS) midsized male finite element model of the human body was used to represent the case occupant and reconstruct her injuries using the head injury criterion (HIC), half deflection, thoracic trauma index (TTI), and pelvic force to predict injury risk. A variation study was conducted to evaluate the robustness of the injury predictions by varying the bullet vehicle parameters.

Results

The THUMS thoracic injury metrics resulted in a calculated risk exceeding 90% for AIS3+ injuries and 70% risk of AIS4+ injuries, consistent with her thoracic injury outcome. The THUMS model predicted seven rib fractures compared to the case occupant's 11 rib fractures, which are both AIS3 injuries. The pelvic injury risk for AIS2+ and AIS3+ injuries were 37% and 2.6%, respectively, consistent with the absence of pelvic injury. The THUMS injury prediction metrics were most sensitive to bullet vehicle location. The maximum 95% confidence interval width for the mean injury metrics was only 5% demonstrating high confidence in the THUMS injury prediction.

Conclusions

This study demonstrates a variation study methodology in which human body models can be reliably used to robustly predict injury probability consistent with real world crash injury outcome.     

Injury risks between first- and second-generation airbags in frontal motor vehicle collisions

BACKGROUND: Airbags in vehicles manufactured after 1997 were depowered to decrease injury risks for infants/children and small adults. It is possible that compared to earlier airbags second-generation airbags provide less injury protection due to their depowered nature. METHODS: A cohort study was conducted using 1995-2004 national data. Risk ratios (RRs) and 95% confidence intervals (CIs) compared injury risks for occupants involved in frontal collisions in vehicles wherein a first- or second-generation airbag deployed by body region and injury severity using the Abbreviated Injury Scale (AIS). Associations were adjusted for crash severity, seatbelt use, seat position, occupant location, and vehicle curb weight. RESULTS: For upper extremity injuries reduced RRs were observed for AIS 1 or greater (RR=0.76, CI 0.67-0.86), AIS 2 or greater (RR=0.76, CI 0.58-1.00) and AIS 3 (RR=0.81, CI 0.64-1.03). Elevated risks were observed for AIS 5 thoracic injuries (RR=1.46, CI 1.04-2.07) but were made null when differences in age and gender were adjusted for. CONCLUSIONS: Vehicles equipped with first- and second-generation airbags appear to offer similar protection for front-seated occupants. The observed decreased risks for upper extremity injury and increased risks for severe thoracic injuries warrant further attention.     

The influence of body mass index on thoracic injuries in frontal impacts

For this study, a comprehensive analysis was performed to assess the influence of body mass index on thoracic injury potential. The data for this study were obtained from the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) database for years 1993-2005. Obese occupants had a 26 and 33% higher risk of AIS > or = 2 and AIS > or = 3 thoracic injury when compared to lean occupants. The increased risk of AIS > or = 3 injury due to obesity was slightly higher for older occupants, but the influence of age was greater than that of obesity. The increase in injury potential was higher for unbelted obese occupants than unbelted. Non-parametric and parametric risk curves were developed to estimate the risk of thoracic injury based on occupant BMI, belt use and delta-V. Overall, increase in thoracic injury risk due to obesity is more prominent in males and older occupants and for occupants sustaining AIS > or = 3 thoracic injuries.     

Are all-terrain vehicle injuries becoming more severe?

BACKGROUND: There are several reasons to suspect that injuries from all-terrain vehicles (ATV) have become both more serious and frequent in recent years. These reasons include increasing engine power, younger age of operators and inconsistent enforcement of helmet laws. The purpose of this study was to determine if the increase in ATV injuries was out of proportion to the increase in ATV usage and whether ATV injuries have increased in severity. METHODS: A retrospective analysis of the Consumer Product Safety Commission (CPSC) ATV injury data and the Pennsylvania Trauma System Foundation (PTSF) database from 1989 to 2002 was performed. ATV use, sales, deaths, trauma center admissions, Injury Severity Score (ISS), hospital length of stay (LOS) and Glascow Coma Score (GCS) were reviewed. RESULTS: ATV sales increased to 316%. In the decade prior to 2003, reported deaths nationally increased from 183 to 357 (95%) nationally and from 5 to 10 (100%) in Pennsylvania (PA). Admissions to trauma centers in PA increased 240%, yet the percentage of deaths to trauma center admissions remained constant at 2.6% during this period (p>.50). ISS and LOS from 1989 to 2002 did not significantly change (all p>.05) and GCS improved significantly. CONCLUSION: Despite concerns regarding the increasing dangers associated with ATVs, it appears that the severity of injuries from ATV use has not increased.     

Road traffic accidents and the Abbreviated Injury Scale (ais) in Japan

Although in Japan the number of casualties from road traffic accidents decreased substantially during a period of improvement of safety measures, in recent years it has remained rather constant. To decrease accidents still further it is necessary to investigate the circumstances of road traffic accidents and the severity of resulting casualties in detail. For this purpose 167,721 cases of road traffic accident casualties occurring between February and April 1979, throughout Japan were analyzed. (1) It was found that 74.2% of all the cases suffered injuries corresponding to AIS-1; 30% of these involved neck injuries. (2) There were 2,654 fatal cases, 67% of which involved head injuries, chiefly cerebral contusion, cranial base fracture, and intracranial hemorrhage. There were fatal cases in the categories of AIS-3 or below which are generally considered not fatal, but those were due to complications. (3) The chief sites of injury varied according to the victim's mode of transport: in an automobile the neck was the site most frequently injured; on a motorcycle the legs and head were usually involved; on a bicycle or walking the head and legs were most at risk. (4) Injuries to pedestrians often fell under the severer AIS-4 or higher codes and constituted 43% of total deaths. (5) Accidents with automobiles changing lanes tended to cause serious injuries and many deaths. Other characteristics of road traffic accidents in Japan are analyzed and discussed.