Elixhauser Comorbidity Software Refined for ICD-10-CM

The Elixhauser Comorbidity Software Refined for ICD-10-CM is one in a family of databases and software tools developed as part of the Healthcare Cost and Utilization Project (HCUP), a Federal-State-Industry partnership sponsored by the Agency for Healthcare Research and Quality. HCUP databases, tools, and software inform decision making at the national, State, and community levels.

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The Elixhauser Comorbidity Software Refined for ICD-10-CM assigns data elements that identify different pre-existing conditions based on secondary diagnoses (i.e., comorbidities) listed on hospital administrative data. In health services research, it is often important to control for comorbidities that are not directly related to the reason for the inpatient stay or outpatient encounter as they can impact resource allocation (e.g., length of stay or charges), as well as possibly affect outcomes used to assess the quality of care, such as in-hospital mortality. The Elixhauser Comorbidity Software Refined for ICD-10-CM is based on the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) diagnosis codes with indicators whether the diagnoses were present on admission (POA).

The Elixhauser Comorbidity Software was originally developed using ICD-9-CM diagnosis codes and diagnosis-related groups (DRGs) to identify comorbidites.1 The software was translated into ICD-10-CM prior to the availability of ICD-10-CM-coded data and released as a beta version. Once ICD-10-CM-coded data became available, the beta version was evaluated by clinical experts. The recommended modifications (implemented in v2021.1) transition the software tool out of its beta status and into the Elixhauser Comorbidity Software Refined for ICD-10-CM.

The Elixhauser Comorbidity Software Refined for ICD-10-CM retains the same clinical intent of defining a comprehensive list of comorbidity measures for use with large administrative databases, however refinements were made to the clinical criteria used for identification of comorbidities and also with some of the comorbidity measures themselves. The number of comorbidity measures increases from 29 to 38 in v2021.1 with three measures added, five measures modified to create 12 more specific measures, and one measure discontinued. A subset of the comorbidity measures uses the POA indicators to determine whether the condition indicated by the secondary diagnosis arose prior to or during the hospital stay. The remaining comorbidity measures do not use POA indicators because the condition can be assumed to be pre-existing and not the result of hospital care (e.g., diabetes, AIDS).


1 Elixhauser, Anne, et al. Comorbidity Measures for Use with Administrative Data. Medical Care, vol. 36, no. 1, 1998, pp. 8-27 JSTOR, https://www.jstor.org/stable/3766985. Exit Disclaimer Accessed 5 Sept. 2020.
 
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The following table provides information on where to find the various resources available for the Elixhauser Comorbidity Software Refined for ICD-10-CM tool. The download section includes all of the referenced materials.

Descriptions Elixhauser Comorbidity Resource
Development of Elixhauser Comorbidity Software Refined for ICD-10-CM User Guide: Elixhauser Comorbidity Software Refined for ICD-10-CM, Description of the Elixhauser Comorbidity Software Refined and Appendix A
Mapping diagnosis codes with more than one comorbidity measure User Guide: Elixhauser Comorbidity Software Refined for ICD-10-CM, Mapping of ICD-10-CM Diagnosis Codes into More Than One Comorbidity Measure and Appendix B
ICD-10-CM coding guidelines that may impact the identification of comorbidities User Guide: Elixhauser Comorbidity Software Refined for ICD-10-CM, ICD-10-CM Coding Guidelines that May Impact the Identification of Comorbidities
 
Technical guidance for applying the Elixhauser Comorbidity Software Refined for ICD-10-CM to administrative data Elixhauser Comorbidity Resource
System requirements User Guide: Elixhauser Comorbidity Software Refined for ICD-10-CM, Using the Downloadable Elixhauser Comorbidity Measure for ICD-10-CM Files, System Requirements
Input files User Guide: Elixhauser Comorbidity Software Refined for ICD-10-CM, Using the Downloadable Elixhauser Comorbidity Measure for ICD-10-CM Files, Downloadable Files
Running the SAS program User Guide: Elixhauser Comorbidity Software Refined for ICD-10-CM, Using the Downloadable Elixhauser Comorbidity Measure for ICD-10-CM Files, Downloadable Files and Running the SAS Program to Add Comorbidity Measures to Data
 
Additional resources Elixhauser Comorbidity Resource
Searchable list of measures in the Elixhauser Comorbidity Software Refined for ICD-10-CM Elixhauser Comorbidity Software Refined for ICD-10-CM Reference File, tab Comorbidity Measures
Searchable log of changes across versions Elixhauser Comorbidity Software Refined for ICD-10-CM Change Log

 
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The ZIP folder includes the CSV mapping file, a SAS mapping program, and all of the user documentation. At this time, the Elixhauser Comorbidity Software Refined for ICD-10-CM tool is only available as a SAS program.

Elixhauser Comorbidity Software Refined for ICD-10-CM v2021.1: Fiscal Year 2021, Released October 2020 - valid for ICD-10-CM diagnosis codes through September 2021
For convenience, the user documentation for the Elixhauser Comorbidity Software Refined for ICD-10-CM v2021.1 is also provided as separate documents:

 
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Copies of previous versions of the Elixhauser Comorbidity Software Refined tool and the beta versions for ICD-10-CM are available for users who need to replace or access the old programs and documentation.

 
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Questions regarding the Elixhauser Comorbidity Software Refined may be directed to HCUP User Support through the following channels:

 
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Internet Citation: Elixhauser Comorbidity Software Refined for ICD-10-CM Healthcare Cost and Utilization Project (HCUP). October 2020. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/toolssoftware/comorbidityicd10/comorbidity_icd10.jsp.
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Last modified 10/23/20