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Table 3. Differences Between NIS Release 4 and NHDS Files Used in This Analysis

Characteristic Database
NIS Release 4 NHDS
Intended Universe Discharges from community hospitals as defined by the AHA—nonfederal, short-term general, or other special hospitals that are not a hospital unit of an institution. Discharges from short-stay hospitals (hospitals with an average length of stay of less than 30 days), general-specialty (medical or surgical) hospitals, or children's hospitals. The NHDS does not include federal, military, and Veterans Administration hospitals, nor does it include hospital units of institutions (i.e., prison hospitals).
Specialty hospitals and units AHA community hospitals may be specialty hospitals. Some AHA community hospitals include specialty units—obstetrics/ gynecology; short-term rehabilitation; and ear, nose, and throat. Includes discharges from a few specialty hospitals (i.e., psychiatric, maternity, alcohol/chemical dependency, orthopedic, and head injury rehabilitation hospitals).
HMO enrollees Included Included
Bedside No restriction on bedside. Must have at least six beds staffed for patient use.
Sample or Universe Sample Sample
Sampling Frame 19 states 50 states and the District of Columbia
Sample Design By geographic region, control/ownership, location, teaching status, and bedside (bedside categories are specific to the hospital's location and teaching status).
938 hospitals.		 Includes all hospitals with at least 1,000 beds or more than 40,000 discharges annually—plus an additional sample of hospitals based on a stratified three-stage design. Approximately 490 hospitals.
Discharges included in database All discharges from sampled hospitals: approximately 6.7 million. A sample of discharges from sampled hospitals: approximately 260,000 discharges.
Charges Reported charges missing for some HMO enrollees. Not reported
Reassignment of diagnosis codes None Myocardial infarctions are reassigned to the principal diagnosis when other circulatory diagnoses are present.

For women discharged after a delivery, a code of V27 (Outcome of Delivery) from the supplemental classification is entered as the second-listed code, with a code designating normal or abnormal delivery in the first-listed position.

If the first-listed diagnosis was a symptom, it was reassigned as a secondary diagnosis.

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Page last reviewed December 2012
Page originally created December 2012
Internet Citation: Table 3. Differences Between NIS Release 4 and NHDS Files Used in This Analysis. Content last reviewed December 2012. Agency for Healthcare Research and Quality, Rockville, MD. https://archive.ahrq.gov/research/data/hcup/nhds/comptb3.html

The information on this page is archived and provided for reference purposes only.

 
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