A multi-decade joinpoint analysis of firearm injury severity

BACKGROUND: Non-fatal firearm injuries constitute approximately 70% of all firearm trauma injuries in the United States. Patterns of severity of these injuries are poorly understood. We analyzed the overall, age-, sex- and intent-specific temporal trends in the injury severity of firearm hospitalizations from 1993 to 2014. METHODS: We assessed temporal trends in the severity of patients hospitalized for firearm using Nationwide Inpatient Sample (NIS) data over a 22 year period. Firearm hospitalization was identified using assault (E965x), unintentional (E922x), intentional self-harm (E955x), legal (E970) and undetermined (E985x) International Classification of Diseases, Ninth Revision, Clinical Modification (ICD9) codes. Injury severity was measured using the computed New Injury Severity Score (NISS). We used survey weighted means, SD and annual percent change (APC), and joinpoint regression to analyze temporal trends. RESULTS: A weighted total of 648 662 inpatient admissions for firearm injury were analyzed. Firearm injury severity demonstrated a significant annual increase of 1.4% (95% CI=1.3 to 1.6), and was driven by annual increases among young adults (APC=1.4%, 95% CI=1.3 to 1.5), older adults (APC=1.5%, 95% CI=1.3 to 1.6), female (APC=1.5%, 95% CI=1.3 to 1.6) and male (APC=1.4%, 95% CI=1.3 to 1.6) hospitalizations. The annual increase among assault/legal injuries was 1.4% (95% CI=1.3 to 1.5), similar to unintentional (APC=1.4%, 95% CI=1.3 to 1.6), intentional self-harm (APC=1.5%, 95% CI=1.4 to 1.6) and undetermined (APC=1.4%, 95% CI=1.3 to 1.6). CONCLUSIONS: The severity of hospitalized firearm injuries increased significantly from 1993 to 2014. This annual increase reflects a move towards hospitalization of more serious injuries, and outpatient management of less serious injuries across the board, suggesting a mounting burden on the US healthcare system. LEVEL OF EVIDENCE: Level IV.