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Patient Trend Database Source Information

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Database Source Overview

TDR Database Audit type Data source Facilities included Facilities excluded Size of audit**

HIP

Inpatient - (Diagnoses & Procedures) National Hospital Discharge Survey (NHDS)

Full documentation (pdf)
Short-stay hospitals (hospitals with an average length of stay for all patients of less than 30 days) or those whose specialty is general (medical or surgical) or children's general are included in the survey. Federal, military, and Veterans Administration hospitals 2009: 205 hospitals

A total of 162,151 patient records were used to the 2009 dataset.

ER

Emergency Room (Diagnoses) National Hospital Ambulatory Medical Care Survey (NHAMCS)

Full documentation (pdf)
Hospitals with an average length of stay for all patients of less than 30 days (short-stay) or hospitals whose specialty was general (medical or surgical) or children's general were eligible. Federal hospitals, hospital units of institutions, and hospitals with less than six beds staffed for patient use. 2008: 431 Emergency Departments

A total of 34,134 patient records were used for the 2008 dataset.

HOP

Outpatient (Diagnoses) National Hospital Ambulatory Medical Care Survey (NHAMCS)

Full documentation (pdf)
Hospitals with an average length of stay for all patients of less than 30 days (short-stay) or hospitals whose specialty was general (medical or surgical) or children's general were eligible. Federal hospitals, hospital units of institutions, and hospitals with less than six beds staffed for patient use. 2008: 924 clinics within 209 outpatient departments

A total of 33,908 patient records were used for the 2008 dataset.

POP

Physician Office (Diagnoses) National Ambulatory Medical Care Survey (NAMCS)

Full documentation (pdf)
-- Office-based, as defined by the AMA and AOA;

-- Principally engaged in patient care activities;

-- Nonfederally employed;

-- Not in specialties of anesthesiology, pathology, and radiology.
2009: 1,246 physicians responded with patient records.

A total of 32,281 patient records were used for the 2009 dataset.

NSAS

National Survey of Ambulatory Surgery (Procedures) National Survey of Ambulatory Surgery (NSAS)
Full documentation (pdf)
Ambulatory surgery procedures performed in short-stay hospitals and freestanding ambulatory surgery centers. Federal, military, and Department of Veteran’s Affairs hospitals. A total of 52,233 Patient records were used for the 2006 dataset.

** Numbers in this column are unweighted. However, data output in TDR's databases are weighted to estimate discharges for all U.S. facilities that correspond to the inclusion criteria.

How does the NHDS differ from the National Inpatient Sample published by HCUP?

The NIS uses a larger sample and is created by combining datasets from individual states.  However, not all U.S. states are represented in the sample.  For an in-depth comparison, see: Comparative Analysis of HCUP (NIS) and NHDS Inpatient Discharge Data.