Of the $377.5 billion aggregate hospital inpatient costs in 2012, 46 percent was for Medicare-covered stays and 16 percent was for Medicaid-covered stays. Thus, patients covered by government payers accounted for at least 62 percent of all hospital costs.

■ More than half of Medicare-covered and uninsured stays were medical (55 percent and 54 percent, respectively). More than half of stays covered by private insurance were surgical (52 percent).

■ Maternal and neonatal stays constituted 27 percent of costs for Medicaid, 15 percent of costs for private insurers, and 4 percent of costs for uninsured patients.

■ Mean hospital costs in 2012 were highest for surgical stays ($21,200)—2.5 times the mean costs for medical stays ($8,500) and nearly five times the mean costs for maternal and neonatal stays ($4,300).

■ Patients aged 45–64 and 65–84 years had the highest mean hospital costs in 2012 ($12,900 and $13,000, respectively), but patients under age 18 had the highest growth in mean costs between 2008 and 2012 (more than 6 percent annually).

■ Among payers of hospital stays, Medicare had the highest mean hospital costs in 2012 ($12,200), but between 2008 and 2012 mean Medicare costs grew at the lowest annual rate (0.9 percent).

■ Average annual growth in aggregate hospital costs slowed from 5.2 percent in the 2003–2008 time period to 2.1 percent in the 2008–2012 time period.

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