HCUP HOSPITAL IDENTIFIERS
This section describes how HCUP reconciles the hospital identifiers used by the HCUP Partners for their statewide databases with hospital identifiers used by the American Hospital Association.

Table of Contents
HCUP HOSPITAL IDENTIFIERS

RECONCILING HOSPITAL IDENTIFIERS RULES FOR RESOLVING PROBLEM HOSPITALS

Table of Tables

Table 1. Linkages Between AHA and Data Source Identifiers

Table 2. Example of Different Source Identifiers Mapped to One AHA Identifier

Table 3. Example of Hospital Openings

Table 4. Example of Hospital Closures

Table 5. Example of Hospital Mergers

Table 6. Example of Hospital Demergers

Table 7. Example of Changes in Hospital Characteristics
 
HCUP HOSPITAL IDENTIFIERS
This document describes the different hospital identifiers included in the Healthcare Cost and Utilization Project (HCUP) databases and the process used to reconcile the hospital identification used by the HCUP Partner organizations and the American Hospital Association (AHA).

HCUP State Databases

The HCUP Partners determine which hospital identifiers, if any, may be released on the HCUP State Inpatient Databases (SID), State Emergency Department Databases (SEDD), and State Ambulatory Surgery and Services Databases (SASD). Up to three hospital identifiers are included in the HCUP databases:
  • The HCUP Partners own number scheme for identifying hospitals and facilities (HCUP data element: DSHOSPID),
  • The hospital identifier used by the AHA (HCUP data element: AHAID or IDNUMBER), and
  • A unique HCUP hospital identifier (HCUP data element: HOSPID).
Once the data source's identification of the hospital is reconciled with the identification of the hospital in the AHA, data from the AHA Annual Survey are used to:
  • identify facilities that are defined by the AHA as "community hospitals;"
  • classify each community hospital into a stratum for sampling for the HCUP nationwide databases;
  • add various types of information about the hospital (such as its county FIPS code) to the nationwide and State databases; and
  • identify community hospitals listed in the AHA Annual Survey for which no inpatient data were supplied by the data source.
HCUP Nationwide Databases

Hospital identifiers vary depending on the nationwide database and the year:
  • The National Inpatient Sample (NIS) and the Kids' Inpatient Sample (KID), beginning in 2012, include a unique HCUP hospital identifier, HOSP_NIS or HOSP_KID, respectively. These hospital identification numbers are reassigned each year. Therefore, it is not possible to link the NIS or KID to other HCUP or external databases or to track the same hospital across years. The use of these hospital pseudo-identifiers helps protect identities while preserving the analyst's ability to estimate hospital-level variation.
    • Prior to 2012, the NIS and KID contained the unique HCUP hospital identifier, HOSPID. The HOSPID could be used to link to other HCUP databases. The HOSPID could also be used to track the same hospital across years.
  • The Nationwide Readmissions Database (NRD) contains HOSP_NRD for all years. This is similar to HOSP_NIS and HOSP_KID where the hospital identification numbers are reassigned each year Therefore, it is not possible to link to other HCUP or external databases or to track the same hospital across years.
  • The Nationwide Ambulatory Surgery Sample (NASS) contains HOSP_NASS for all years. This is similar to HOSP_NIS and HOSP_KID where the hospital identification numbers are reassigned each year. Therefore, it is not possible to link to other HCUP or external databases or to track the same hospital across years.
  • The Nationwide Emergency Department Sample (NEDS) contains HOSP_ED for all years. HOSP_ED identifies ED records that are associated with the same hospital-owned ED. It does not link to other HCUP databases or external databases. However, it can be used to identify the same hospital across years. Once a HOSP_ED value is assigned to an emergency department, the same value is retained each year.
Once the data source's identification of the hospital is reconciled with the identification of the hospital in the AHA, data from the AHA Annual Survey are used to:
  • Identify facilities that are defined by the AHA as "community hospitals;"
  • Identify community hospitals listed in the AHA Annual Survey for which no inpatient data were supplied by the data source for the SID.
  • Classify each community hospital into a stratum for sampling for the HCUP nationwide databases;
  • Add information about the hospital to the nationwide and State databases
    • For State databases that allow hospital identifiers to be released, a AHA Linkage File is available. This file contains a small number of data elements that allow researchers to link the HCUP State databases to the AHA Annual Survey (which must be purchased separately) to supplement the HCUP State databases with hospital characteristics. Users can merge the data elements of interest from the AHA Annual Survey Databases to the HCUP AHA Linkage Files using AHAID, and then subsequently link to the HCUP State databases by using DSHOSPID.
    • For the nationwide databases, limited hospital characteristics are available on the files. These include census division and region of the hospital, urban-rural designation, teaching status, bed size, control/ownership of the hospital, and trauma center level (NEDS only).
      • Prior to 2012, HOSPID could be used to link the NIS or the KID to the AHA Annual Survey to supplement with additional hospital information (such as its county FIPS code). This is not possible starting in data year 2012.
Note: Generally, AHA identifiers can be determined for community and non-community hospitals that are registered with the AHA. AHA identifiers are not available for non-hospital-owned ambulatory surgery centers.
 
RECONCILING HOSPITAL IDENTIFIERS
The goal is to identify an appropriate AHA hospital identifier for each source hospital in a given year.

To begin, relevant data elements are extracted from State data and from the AHA data for each year. The two elements extracted from the State data are:
  • the source-specific hospital identifier (DSHOSPID), and
  • a count of the hospital's inpatient records for each quarter and for the year in the State Inpatient Databases (SID).

 
Linkage of Source and AHA Hospital Identifiers
First, the hospital identifiers used by the data source (herein referred to as DSHOSPID) are linked to the relevant data elements extracted from the AHA Annual Survey of Hospitals data. AHA identifiers include all hospitals in the state, not just the community hospitals.

A SAS merge step is used to link the DSHOSPIDs to AHA identifiers. The specific variables used in the merge depend on the information provided by the data source. In order of preference, these variables are:
  • hospital name, city, and zip code;
  • hospital name; or
  • any other unique variable that is available - e.g., Medicare provider number.
The AHA and the data source often use different methods to represent components of a hospital's name (e.g., "Community General Hospital" may be represented as "Community General Hosp" by the AHA and as "Community Gen Hosp" by the data source). Hence, before the SAS merge, the AHA and the source's hospital names are transformed into a uniform link variable, which imposes similar methods of abbreviations, lowercase and uppercase letters, and different characters. This effectively reduces the number of non-merges that occur simply because of different methods of representing the hospital name's components.

Three types of linkages result from this step, as shown in Table 1.

Top
Table 1. Linkages Between AHA and Data Source Identifiers
Row AHA Identifier DSHOSPID Link?
1 present present yes
2 present absent no
3 absent present no


Top
 
Approximately 80 percent of DSHOSPIDs link to AHA identifiers in this step. (These successful links are represented by Row 1 in Table 1). The other 20 percent of DSHOSPIDs (Rows 2 and 3) must be linked manually, using the process described below.

Prior experience has shown that a large majority of the hospitals failing to link in this step will usually be due to:
  • closures,
  • openings (new hospitals),
  • mergers,
  • demergers,
  • dates of changes in the hospital structure that differ between the data source and the AHA Annual Survey, and
  • levels of aggregation that differ between the data source and the AHA Annual Survey (e.g., the data source treats two separate facilities as two hospitals, while the AHA Annual Survey treats the two facilities as a single hospital, or vice versa).
 
Resolution of Unmatched Hospitals
The goal in this step is to identify an appropriate AHA hospital identifier for each source hospital that was not matched above.

Several external sources of information are used to reconcile the unmatched AHA hospitals (Row 2) and the unmatched source hospitals (Row 3). These are:
  • Source Documentation: This information, received from the data source, usually contains a list of hospitals, their cities (specific addresses are not always included), and the source's hospital identifier. This documentation is the primary source for finding missing information (e.g., specific names and addresses) for an unmatched hospital.


  • AHA Guide: The AHA Guide, an annual hard-copy volume published by the AHA, provides a wealth of information about registered hospitals. The AHA Guide includes an entire section on multihospital health-care systems that identifies the hospitals included in specific multi-hospital systems. The AHA Guide also provides information about individual hospitals (organized by state, and within each state, by city), which includes:


    • Information also available from the AHA Annual Survey data; for example:
      • type of service (general medical/surgical, rehabilitation);
      • average lengths of stay (long- or short-term);
      • type of ownership; and
      • numbers of beds, admissions, births, etc.

    • Information about hospitals embedded within the organizational structure of another hospital; for example:
      • Binghamton, Broome County, NY
          United Health Services (includes Binghamton General Hospital, Mitchell Ave. ...; Wilson Memorial Hospital, ... Harrison St. ...)

    • Information about changes in a hospital's name; for example:
      • Dobbs Ferry, Westchester County, NY
          Community Hospital at Dobbs Ferry (formerly Dobbs Ferry Hospital)

    • References to a new hospital name or new location; for example:
      • Delhi, Delaware County, NY
          A. Lindsay and Olive B. O'Connor Hospital. See Mary Imogene Bassett Hospital, Cooperstown.


  • AHA Summaries: The AHA Summary of Registered Hospitals and the AHA Summary of Nonregistered Hospitals, which are usually delivered with the annual AHA Guide, document additions and deletions reflected in the hospitals' responses to the AHA Annual Survey.


  • Record counts generated from the supplied inpatient data:
    The number of discharges reported in the inpatient data is compared to the number of discharges reported to the AHA. While this information is rarely definitive in linking source identifiers to AHA identifiers, it is sometimes useful in identifying a link to an AHA hospital, and provides a means of validating linkages obtained by other means. This information is especially useful in distinguishing a single hospital from two combined hospitals.

When it is not clear what needs to be done to a hospital or group of hospitals, an AHRQ analyst is consulted.

When the reconciliation process is complete:

  • An AHA identifier (AHAID and IDNUMBER) has been assigned to all hospitals registered with the AHA,
  • all hospitals with a non-missing AHA identifier have been assigned an HCUP hospital identifier (HOSPID), and
  • all hospitals with a non-missing AHA identifier have only one FIPS county code assigned.

    Hospitals composed of multiple facilities in different locations are assigned the FIPS county code of the major facility, as defined by the AHA.

The HCUP data element AHAID contains the hospital number used on AHA Annual Survey of Hospitals data file available through the AHA. The HCUP data element IDNUMBER contains the same identifier with the leading "6" removed.

Top
 
RULES FOR RESOLVING PROBLEM HOSPITALS
Following are the rules used for resolving problem hospitals. In these examples, the HCUP hospital identifier (HOSPID) starts with "SS" to indicate the state FIPS code:

The HCUP hospital identifier (HOSPID) reflects the AHA view of a hospital and is a randomly assigned number based on the AHA hospital identifier (AHAID and IDNUMBER). If the data source reports the data from facilities that are combined in the AHA hospital definition, the IDNUMBER and the HOSPID will be the same for all the facilities. In the following example, three different source identifiers are considered to be part of one facility as defined by the AHA:

Top
Table 2. Example of Different Source Identifiers Mapped to One AHA Identifier
Year Data Source AHA IDNUMBER HOSPID
2018 165 (Acute Care Unit) 910140 SS089
2018 165P (Psychiatric Unit) 910140 SS089
2018 166S (Swing Bed Unit) 910140 SS089


Top
 
Openings

The AHA AHAID/IDNUMBER and HCUP HOSPID are assigned to a newly opened hospital only when the hospital has first been recognized by the AHA for a particular survey year, even if the data source supplies data for an earlier time period. For example, the data source supplied data for a hospital starting in 2016, but the AHA first recognized the hospital in 2018:

Top
Table 3. Example of Hospital Openings
Year Data Source AHA IDNUMBER HOSPID
2016 86-0601625    
2017 86-0601625    
2018 86-0601625 860001 SS014
2019 86-0601625 860001 SS014


Top
 
Closures

When a hospital closes (in the AHA's view), the AHAID/IDNUMBER and HCUP HOSPID are carried forward if there are inpatient data available from the data source. In this example, the AHA considered the hospital closed in 2017, but the data source still supplied data:

Top
Table 4. Example of Hospital Closures
Year Data Source AHA IDNUMBER HOSPID
2015 047 450520 SS171
2016 047 450520 SS171
2017 047 450520 (closed) SS171


Top
 
Mergers

When two or more hospitals merge (in the AHA's view), the IDNUMBER (along with the AHAID and HOSPID) of the merged entity is assigned to all its component hospitals even if they continue reporting separately to the state. In this example, two hospitals have different source identifiers, but starting in 2017 are considered one facility by the AHA because of a merger:

Top
Table 5. Example of Hospital Mergers
Year Data Source AHA IDNUMBER HOSPID
2016 036 450400 SS091
2017 036 450002 (merger) SS013
2018 036 450002 (merger) SS013
2019 036 450002 (merger) SS013
 
2016 126 451750 SS169
2017 126 450002 (merger) SS013
2018 126 450002 (merger) SS013
2019 126 450002 (merger) SS013


Top
 
Demergers

When hospitals demerge (in the AHA's view), the component hospitals are assigned a new AHAID/IDNUMBER or the one they previously had. The HCUP HOSPID follows the AHA IDNUMBER, so that the HOSPID changes if the AHAID/IDNUMBER changes and the HOSPID is reused if the AHAID/IDNUMBER is reused. In this example, a hospital demerges in 2016 into two facilities:

Top
Table 6. Example of Hospital Demergers
Year Data Source AHA IDNUMBER HOSPID
2015 562 220515 (merger) SS051
2016 562 220547 (demerger) SS026
2017 562 220547 (demerger) SS026
 
2015 561 220515 (merger) SS051
2016 561 221240 (demerger) SS037
2017 561 221240 (demerger) SS373


Top
 
Changes in Hospital Characteristics

Note: The following decision is made only after AHRQ is consulted. If during HCUP processing of the data, summary statistics on the distribution of length of stay look questionable for a community hospital (e.g., the mean length of stay is considerably greater than 30 days), the AHA community flag is investigated. If the AHA community flag was imputed from previous years because a hospital did not report to the AHA, and the data source can confirm that the facility is no longer a community hospital, the AHA identifier is still assigned to the facility and the community flag is imputed. In this example, the facility was considered a non-community hospital starting in 2017:

Top
Table 7. Example of Changes in Hospital Characteristics
Year Data Source AHA IDNUMBER HOSPID Community Flag
2015 86-0201864 860575 SS090 1
2016 86-0201864 860575 SS090 1
2017 86-0201864 860575 SS101 0 (changed)
2018 86-0201864 860575 SS101 0 (changed)


Top
 

Internet Citation: HCUP Hospital Identifiers. Healthcare Cost and Utilization Project (HCUP). November 2020. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/maphosp.jsp.
Are you having problems viewing or printing pages on this website?
If you have comments, suggestions, and/or questions, please contact hcup@ahrq.gov.
Privacy Notice, Viewers & Players
Last modified 11/24/20