Shiu Ho

Vehicle Model Year and Crash Outcomes: A CIREN Study

Objective: To quantify the effect of model year (MY) on the occurrence of severe injuries and death after involvement in motor vehicle crashes. Methods: Cases involving adult front seat occupants of vehicles MY ≥ 1994 equipped with frontal airbags were selected from the Crash Injury Research and Engineering Network (CIREN) database. Cases were grouped by MY: 1994–1997, 1998–2004, and 2005–2007 (MY groups [MYG] 1, 2, and 3, respectively. MYGs were compared in relation to mortality, Injury Severity Score (ISS), and the occurrence of Abbreviated Injury Severity score (AIS) 3+ and AIS4+ injuries to each body region using Mantel Haenszel chi-square, Kruskal-Wallis, and Bonferroni corrected t test. To adjust for confounders, multiple logistic regression models were built to explore the association of MYG with death. Covariates included age, BMI, delta v, principal direction of force (PDOF), restraint use, and vehicle type. Results: A total of 1888 cases was distributed within MYG1 (34%), MYG2 (62%), and MYG (34%). Age, gender, BMI, and PDOF distribution did not differ among MYGs. Though ISS distribution was not different, a decrease in the occurrence of AIS4+ of the thorax and spine regions was noted over time. Mortality also decreased over time (18, 9, and 4% MYG 1, 2, and 3, respectively). Multivariate analysis revealed a protective effect of MYG2 and MGY3 (odds ratio [OR], 0.57 [0.44–0.75] and 0.22 [0.07–0.50], respectively) in relation to death. Conclusions: Front seat occupants of later MY vehicles injured during crashes experience a decreased likelihood of very severe thoracic injuries, spinal injuries, and death.

Crash and Occupant Predictors of Pulmonary Contusion

OBJECTIVES Pulmonary contusions (PCs) are a common injury sustained in motor vehicle collisions. The crash and occupant characteristics of PC in motor vehicle collisions are currently unknown. Additionally, the clinical significance and the impact on mortality have not been determined. METHODS A retrospective review of the Crash Injury Research and Engineering Network database with inclusion criteria of frontal (F) and near-side lateral (L) crashes involving occupants older than 15 years, yielded 2,184 case occupants. Pearsons chi and multivariate logistic regression were used with a p < 0.05 conferring statistical significance. RESULTS Median age was 38 years, 80% were drivers and mortality was 16%. Forty-nine percent of case occupants were not wearing lap-shoulder belts. Chest trauma was sustained by 1,131 (52%), of whom 379 had PC. Crash characteristics included: 38 kph median change in velocity (delta V), 72% frontal deformation, and 35% struck a fixed object. Injury characteristics included median Injury Severity Score 17 with the following Abbreviated Injury Score (AIS) >2 injuries: thoracic 40%, abdominal 19%, and head 24%. Univariate predictors of PC included: age <25, male, higher Injury Severity Score, fatality, delta V >45 kph, L impacts, and collision with fixed object. PC was significantly associated with occupant compartment intrusion in F but not L crashes. In multivariate analysis, significant predictors of PC included: age <25 (odds ratios [OR] = 1.5), delta V >45 kph (OR = 1.9), and fixed object (frontal crash only) (OR = 1.8). Controlling for head, spine, abdominal, and extremity injuries AIS >2, PC was not a statistically significant risk factor for mortality. This was consistent whether or not another AIS >2 thoracic injury was present. The effectiveness of side-impact airbags was not evaluated due to the small sample size. CONCLUSIONS Crash severity as demonstrated by higher delta V was strongly associated with PC in all crashes. Frontal crashes with a fixed object or intrusion are more likely to result in a PC. The risk of PC is greatly increased in near-side lateral impacts regardless of intrusion or object struck; suggesting occupant proximity may be the most important factor. Further investigations of the efficacy of side airbags as a counter measure should be considered and continued public education of the efficacy of lap-shoulder restrains should continue. Unexpectedly, although a marker for crash severity, PC is not an independent marker of mortality.

Causation and outcomes of diaphragmatic injuries in vehicular crashes

BACKGROUND This study aimed to identify vehicular and crash factors associated with diaphragmatic injuries (DIs). METHODS DI presence was analyzed among Crash Injury Research and Engineering Network vehicular occupants (age ≥ 16 years) in relation to occupant and crash factors. Contact points (i.e., components in direct contact with occupants) involved in injury causation were analyzed. Cases with and without DI were compared in relation to mortality, Injury Severity Score (ISS) and the occurrence of injuries with a maximum Abbreviated Injury Scale (MAIS) score of 3+. Student’s t test, Wilcoxon test, &khgr;2, and multiple logistic regression were used for statistical analysis. RESULTS Of a total of 2,344 cases with complete data for analysis, 80 cases (3.4%) experienced DI. Multiple logistic regression analysis revealed a significant association with the occurrence of DI for near lateral impact (odds ratio, 7.71 [4.20–14.58]) and change in velocity (&Dgr;V) of 40 km/h or greater (odds ratio 2.58 [1.29–5.24]). The seat belt and steering wheel were the most common contact points among frontal impact crashes, and the side interior surface and side hardware or armrest were the more common contact points among side impact crashes. DI cases experienced more MAIS3+ injuries in the head, chest and abdominal regions and exhibited higher median ISS (q1–q3) [42 (29–62.5) vs. 17 (10–27), p < 0.0001]. While mortality was higher among occupants with DI (48% vs. 14%), this effect disappeared when adjusted by ISS. CONCLUSION DI are associated with lateral crashes and higher &Dgr;V. Head, chest, and abdominal injuries occur more commonly among DI patients, and the presence of these injuries rather than the DI itself is responsible for the increased mortality in these patients. LEVEL OF EVIDENCE Epidemiologic study, level III.