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Nationwide Inpatient Sample (NIS)

Database Name: Nationwide Inpatient Sample (NIS)


Data Source

Administrative database that is the largest all-payer inpatient care database. The NIS was developed as part of the Healthcare Cost and Utilization Project (HCUP), sponsored by the Agency for Healthcare Research and Quality (AHRQ).

Overview of data contents

The NIS represents a 20 percent stratified sample of the United States community hospitals, currently containing data from 10 million inpatient stays in 45 hospitals from 46 states. Data include clinical and nonclinical elements: diagnoses, procedures, admission, and discharge status, patient demographics, payment source, total charges, length of stay, and hospital and provider characteristics.

Patient ages included


Practice setting


Date range available

Data collection is ongoing. The database was initiated in 1988, with the number of states contributing data growing over time.

Relevant Work

Example publications

Kezerian EJ, Maselli J, Vittinghoff E, Goldberg AN, Auerbach AD. Obstructive sleep apnea practice patterns in the United States: 2000-2006. Otolaryngology Head Neck Surgery 2010 Sep;143:441-7.

Bhattacharyya N, Abemayor E. Changing patterns of hospital utilization for head and neck cancer care:implications for future care. JAMA Otolaryngology Head Neck Surgery 2013 Sep 5[Epub ahead of print].

Li R, Fakhry C, Koch WM, Gourin CG. The effect of tumor subsite on short-term outcomes and costs of care after oral cancer surgery. Laryngoscope 2013 July;123:1652-9


Cost estimate(s)

$350 per year of data

Contact/website information


Ease of use

Easy to obtain.

Data analysis

This is a sampling of admissions, but it is somewhat unequal, in that certain states or types of patients (usually defined by demographic variables are over- and under- represented. As a result, weighting algorithms have been developed by HCUP statisticians, specifically for the purpose of developing nationwide estimates from these databases. Most uses of the databases require incorporating the weighting algorithms to develop national estimates. These are complex, so working with a biostatistician (ideally one familiar with these databases) is recommended.


There are many advantages to this database, and the NIS is used widely to address an array of research questions.


The sheer volume of data can make it advantageous to work with a data manager or research associate experienced in working with this database.