Variations in Ambulance Use in the United States: The Role of Health Insurance

Objectives: The purpose of this study was to describe the associations between individual health insurance and ambulance utilization using a national sample of patients who receive emergency department (ED) care. Methods: The data source was the National Hospital Ambulatory Medical Care Survey, years 2004 through 2006. Noninstitutionalized patients between ages 18 and 65 years were included. The primary dependent variable was ambulance use. Multivariable logistic regression methods were used to assess the associations between health insurance status and ambulance use and to adjust for confounders. Results: A total of 61,013 ED visits were included, representing a national sample of approximately 70 million annual ED visits over 3 years. Ambulance transport was used in 11% of private insurance visits, 16% of Medicaid visits, and 13% of uninsured visits. In the adjusted model, visits by patients with Medicaid (adjusted odds ratio [aOR] = 1.60, 99% confidence interval (CI) = 1.37 to 1.86) and the uninsured (aOR = 1.43, 99% CI = 1.23 to 1.66) were more likely to arrive by ambulance than visits by patients with private insurance. Ambulance use among the uninsured was most pronounced in metropolitan areas. Conclusions: Ambulance use varies by health insurance status. Medicaid coverage and lack of insurance are each independently associated with increased odds of ambulance use, suggesting a disproportionate role for emergency medical services (EMS) in the care of patients with limited financial resources. ACADEMIC EMERGENCY MEDICINE 2011; 18:1036-1044 (C) 2011 by the Society for Academic Emergency Medicine