The Healthcare Cost and Utilization Project (HCUP) National Inpatient Sample (NIS) featuring 2015 data is now available. The NIS is the largest all-payer inpatient care database in the United States. The NIS is nationally representative of all short-term, non-Federal hospitals in the U.S. It is drawn from the HCUP State Inpatient Databases (SID) and includes more than 7 million hospital discharges from 46 States and the District of Columbia, covering more than 97 percent of the U.S. population. The NIS includes patients from all payer types, including Medicare, Medicaid, private insurance, and the uninsured.

Following the transition to ICD-10-CM/PCS on October 1, 2015, the file structure of the 2015 NIS has changed. Users are encouraged to review the ICD-10-CM/PCS Resources Page prior to analyzing outcomes affected by this change in the ICD coding scheme. To signify the change in the data, the file structure of the 2015 NIS differs from the annual files for other data years. In the 2015 NIS, the first three quarters of data (with ICD-9-CM codes) are stored separately from the fourth quarter of data (with ICD-10-CM/PCS codes). In addition, the names of diagnosis- and procedure-related data elements under ICD-10-CM/PCS have been changed to identify the coding scheme. Data elements based on the HCUP Tools that are derived from ICD-10-CM/PCS codes are not included in the fourth quarter data, but beta version of the programs to assign the HCUP Tools are available for download on the HCUP Tools & Software section of the HCUP-US website.

The NIS can be used by researchers and policymakers to identify, track, and analyze national trends in health care utilization, access, charges, quality, and outcomes. The vast size of the NIS enables analyses of infrequent conditions, uncommon treatments, and special patient populations.

As part of the HCUP database family, the NIS is considered by health services researchers to be one of the most reliable and affordable databases for studying important healthcare topics. The 2015 NIS can be purchased through the HCUP Central Distributor. Additional information is located on the NIS Overview Page.