Medicare has lowered its star ratings for staffing levels in one out of 11 of the nation’s nursing homes — almost 1,400 of them — because they were either inadequately staffed with registered nurses or failed to provide payroll data that proved they had the required nursing coverage, federal records released this week show.

Medicare only recently began collecting and publishing payroll data on the staffing of nursing homes as required by the Affordable Care Act of 2010, rather than relying as it had before on the nursing homes’ own unverified reports.

The payroll records revealed lower overall staffing levels than the homes had disclosed, particularly among registered nurses. Those are the highest-trained caregivers required to be in a nursing home, and they supervise other nurses and aides. Medicare mandates that every facility have a registered nurse working at least eight hours every day.

“It’s a real positive that they actually are taking the payroll-based system seriously, that they’re using it to punish those nursing homes that either aren’t reporting staffing or those that are below the federal limit,” said David Grabowski, a professor of health care policy at Harvard Medical School. “Could they do more? Sure, but I think it’s a really good start.”