High Quality Content by WIKIPEDIA articles! The Oklahoma Hospital Association (OHA) is the state affiliate of the American Hospital Association. It was established on May 21, 1919 after meeting of representatives from 20 Oklahoma hospitals, electing Dr. Fred S. Clinton as the first president. He served as president for the first nine years of the organization`s existence. Today, OHA represents more than 150 hospitals and health care entities, such as nursing homes, home health agencies, surgery centers, medical supply businesses in the U.S. state of Oklahoma.