The extent to which geography explains one of trauma's troubling trends: Insurance-based differences in appropriate interfacility transfer.

Background: A growing body of literature suggests the persistence of a counterproductive triage pattern wherein uninsured adults with major injuries presenting to nontrauma centers (NTCs) are more likely than insured adults to be transferred. Geographic differences are frequently blamed. The objective of this study was to explore geography's influence on variations in insurance transfer patterns, asking whether differences in distance and travel time by road from NTCs to the nearest level 1 or 2 trauma center alter the effect. As a secondary objective, differences in neighborhood socioeconomic disadvantage were also assessed.
Methods: Adults (16-64 years) with major injuries (Injury Severity Score, >15) presenting to NTC emergency departments (EDs) were abstracted from 2007 to 2014 state inpatient/ED claims. Differences in the risk-adjusted odds of admission versus transfer were compared using mixed-effect hierarchical logistic regression and spatial analysis.
Results: A total of 48,283 adults presenting to 492 NTC EDs were included. Among them, risk-adjusted admission differences based on insurance status exist (e.g., private vs. uninsured odds ratio [95% confidence interval], 1.60 [1.45-1.76]). Spatial analysis revealed significant geographic variation ( p < 0.001). However, in contrast to expectations, the largest insurance-based discrepancies were seen in less disadvantaged NTCs located closer to larger trauma centers. Stratified analyses comparing the closest versus furthest distance, shortest versus longest travel time, and least versus most deprived populations agreed, as did sensitivity analyses restricting uninsured transfer patients to those who remained uninsured versus subsequently became insured.
Conclusion: Adults with major injuries presenting to NTCs were less likely to be transferred if insured. The trend persisted after accounting for differences in access to care, revealing that, while significant geographic variation in the phenomenon exists, geography alone does not explain the issue. Taken together, the findings suggest that additional and potentially subjective elements to insurance-based triage disparities at NTCs are likely to exist.
Level of Evidence: Prognostic/Epidemiological, Level III.
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