Long-term acute care hospitals have expanded rapidly in the last 25 years, but statistics show many of them provide substandard care, according to a recent article in The New York Times.

Since 1985, more than 400 such facilities have opened in the U.S., the Times reported last week. Many of them are for-profit, and few have doctors on staff. One reason for the rapid expansion is a rule that reimburses hospitals more for longer-stay patients than for shorter-stay patients. Despite the higher reimbursements, Medicare has never closely examined the care in these facilities, according to the newspaper.

One of the country’s largest long-term acute care hospital operators, Select Medical Corporation, has been cited for Medicare rules violations at a rate four times higher than the national average for regular hospitals, the newspaper reported. Spending on these hospitals rose to $4.8 billion last year, from $400 million in 1993, but a three-year moratorium on new long-term acute care hospitals has kept spending flat since 2007. The moratorium is set to expire at the end of this year, according to the times.