Medicare isn't kidding when it says it wants to reduce hospital readmissions within 30 days of discharge—one of the costliest and most preventable line items in health care spending. The agency has set standards for hospitals that they must either meet or pay penalties for missing. And, it appears, hospitals still aren't getting the message.

Ever since the Hospital Readmission Rate Program (created as part of the Affordable Care Act) took effect four years ago, hospitals have paid big bucks for failing to pay attention to this key indicator of efficiency.

This year, Kaiser Health News reports, nearly 2,600 hospitals were penalized under the law, coughing up $420 million in fines.