The NIS is one database in the ARHQ's Healthcare Cost and Utilization Project (HCUP-3) family of databases. The NIS database contains hospital inpatient stay information taken from 100% of discharges from sampled hospitals in selected states. This design is intended to approximate a 20% sample of U.S. hospitals. Between 700 and 1,000 hospitals per year are included, drawn from between 8 and 38 states. The most recent release of the NIS includes data from Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, Nevada, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oklahoma, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Vermont, Washington, West Virginia, and Wisconsin. Data items in the NIS include demographics, diagnoses, procedures, admission and discharge dates and status, and payer information. The NIS can be linked to hospital-level data from the American Hospital Association's Annual Survey of Hospitals and county-level data from the Bureau of Health Professions' Area Resource File.