Trends in Firearm Injury and Motor Vehicle Crash Case Fatality by Age Group, 2003-2013

Abstract

If changes over time in trauma care apply to both firearm injuries and motor vehicle crashes (MVCs) similarly, differences in mechanism-specific case-fatality trends may suggest changes over time in injury severity. To analyze national trends in case-fatality percentages at levels I and II trauma centers for injuries due to MVC, firearm assault, self-inflicted firearm injury, and unintentional firearm injury by age and to analyze trends in injury severity scores (ISSs) and the percentage of out-of-hospital deaths by mechanism. From November 15, 2017, to July 4, 2018, repeated cross-sectional measures analysis of 1 335 044 patients treated at level I or II trauma centers from January 1, 2003, through December 31, 2013, was conducted using 2 data sources: the National Trauma Data Bank National Sample Program, with survey weights to estimate annual median ISS, total injuries and total deaths at levels I and II trauma centers, and the Centers for Disease Control and Prevention's Wide-Ranging Online Data for Epidemiologic Research for percentages of out-of-hospital deaths. The main outcome was annual case-fatality percentage (total died/total injured), calculated by mechanism across 3 age groups (15-34 years, 35-54 years, and ≥55 years) and 5 categories of ISS (1-15 [mild] 16-24, 25-40, 41-66, and 67-75 [severe]). Linear regression was performed to estimate annual trends in case-fatality percentage by mechanism, age group, and ISS. Annual trends in percentages of out-of-hospital deaths and median ISSs by mechanism were estimated. Sensitivity analyses included the Durbin-Watson statistic for autocorrelation and Prais-Winsten regression models. Among 1 335 044 patients treated at level I or II trauma centers, self-inflicted firearm injury had a case-fatality percentage of 42.8%, and assault with a firearm had a case-fatality percentage of 11.1%, the 2 highest of the injuries studied. The injury case-fatality percentage was lower each year for MVCs but did not change for any firearm intent overall or for any age group. Overall, median ISS increased annually for firearm suicide (0.31; 95% CI, 0.00-0.61). The annual percentage of out-of-hospital deaths was lower each year for MVCs (-0.24; 95% CI, -0.43 to -0.05) but not for any firearm intents. In sensitivity analyses, the annual percentage of out-of-hospital deaths for MVCs no longer showed a decline. Stagnant case-fatality percentages for firearm injuries juxtaposed to improvements for MVCs across age-groups and ISS categories suggests worsening severity of firearm injuries over the study period.