The Agency for Healthcare Research and Quality (AHRQ) announces the release of the Comorbidity Software, Version 3.3, for use with databases available from the Agency's Healthcare Cost and Utilization Project (HCUP) or other healthcare administrative databases.

Comorbidity Software assigns variables that identify comorbidities in hospital discharge records using the diagnosis coding of ICD-9-CM (International Classification of Diseases, Ninth Edition, Clinical Modifications), creating the comorbidity measures reported by Elixhauser et al. ("Comorbidity Measures for Use with Administrative Data." Medical Care, 1998;36:8-27).

The Comorbidity Software consists of two computer programs. The first, Creation of Format Library for Comorbidity Groups, generates a format library that maps diagnosis codes into comorbidity indicators. Additional formats are created to exclude conditions that may be complications or that may be related to the principal diagnosis. The second program, Creation of Comorbidity Variables, applies these formats to a data set containing administrative data.

The Comorbidity Software, Version 3.3 is valid for ICD-9-CM codes, DRGs, and v25 MS-DRGs effective October 1, 2007. It is available for download from the Tools & Software page on the HCUP-US Website. The software is being distributed in ASCII for easy adaptation to other programming languages, such as SAS, SPSS, and Stata. For more information, please visit the Comorbidity Software page, or contact the HCUP Central Distributor by e-mail at HCUPDistributor@ahrq.gov.