Established in 1986, the Sisters of Mercy Health System is one of the largest, Catholic health care systems in the United States. It consists of more than 15 acute care hospitals, outpatient care facilities, physician practices, and skilled nursing and long-term residential care units. The system maintains facilities in Arkansas, Kansas, Louisiana, Mississippi, Missouri, Oklahoma and Texas. The Sisters of Mercy Health System has a staff of over 33,000 people. Its St. John's Mercy Medical Group is a physician-governed practice that specializes in the areas of clinical research, endocrinology, pediatrics, headache and internal medicine, immunology, and obstetrics and gynecology. The system also operates the Mercy Health System of Northwest Arkansas, St. Edward Mercy Health System, and St. Joseph's Mercy Health Center.