Medicare peer review organizations. 
The Medicare Peer Review Organization (PRO) Program is undoubtedly the most ambitious attempt currently operational of a national health insurance program to use external audit to review the quality of medical care.  This article reviews the history of the PRO program, including its genesis in the prior PSRO program, and describes the methods that it currently uses for reviewing the quality of medical care and for sanctioning physicians and hospitals that provide care of inadequate quality.  Finally, the article reviews the meager data currently available indicating possible limitations in the effectiveness of the PRO program.