Sept. 5 (Bloomberg) — Estimates of U.S. health care spending for the next five years have been lowered by two federal agencies, and the Patient Protection and Affordable Care Act is getting much of the credit.

U.S. health spending in 2019 will be $4 trillion, the Centers for Medicare and Medicaid Services said this week, or $500 billion less than the agency projected in 2010 when President Barack Obama's health care overhaul became law. That announcement followed by a week a report from the Congressional Budget Office lowering its five-year cost estimates.

Obamacare has been criticized by Republicans as costly and unsustainable. Now, four years after its arrival, the law's mandated program cuts and the medical practices it encourages — limiting unneeded procedures and keeping people out of the hospital longer — are cited by economists as key ingredients in trimming the nation's medical bill. While the recession has had an influence on the cost slowdown, it doesn't explain it all, according to policy analysts and the CBO.