Clinical Research Using the National Inpatient Sample: A Brief Review of Colorectal Studies Utilizing the NIS Database.

The National Inpatient Sample (NIS) is the largest collection of longitudinal hospital care data in the United States and is sponsored by the Agency for Healthcare Research and Quality. The data are collected from state organizations, hospital associations, private organizations, and the federal government. This database has been used in more than 400 disease-focused studies to examine health care utilization, access, charges, quality, and outcomes of care. The database has been maintained since 1988, making it one of the oldest on hospital data. The focus of this review is to explore and discuss the use of NIS database in colorectal surgery research and to formulate a simplified guide of the data captured for future researchers.