uninsured. Data on payer mix for prehospital care at the national level are unavailable, but as noted earlier, data from regional ambulance services confirm the heavy reliance of pediatric patients on Medicaid or SCHIP for health insurance coverage. However, these regional data also indicate that a large percentage of pediatric ambulance calls are for uninsured children, and therefore not likely to be reimbursed. Indeed, an examination of EMS transports by the Albuquerque, New Mexico, ambulance service (which provides 99 percent of EMS transports in that city) during 1992–1995 showed that 57 percent of transported patients under age 21 were uninsured. That study also found that payment source varied by patient age, with public insurance being overrepresented among patients younger than age 11, private insurance and lack of insurance being overrepresented among those aged 11–16, and lack of insurance being overrepresented among those aged 17–20 (Sapien et al., 1999).

Medicaid is a federal–state health insurance entitlement program that provides coverage for low-income individuals. The program is administered by the states, and the federal government sets guidelines and matches state spending at rates of between 50 and 77 percent, depending on state per capita income (Kaiser Family Foundation, 2004a). Children typically qualify for Medicaid coverage by meeting financial criteria, which vary across states. Federal law mandates coverage of some groups below specified minimum income levels, but also allows states to expand Medicaid eligibility beyond those levels. Medicaid coverage is relatively broad, covering inpatient and outpatient services including emergency services; physician and nurse practitioner services; nursing home and home health care; laboratory and x-ray services; and early and periodic screening, diagnostic, and treatment.