Medicare HOS Research Data Files

Several types of Medicare HOS data files are available for research purposes. Medicare HOS data files are available as public use files (PUFs), limited data sets (LDSs), and research identifiable files (RIFs).

HOS PUFs contain the majority of the survey items collected on the HOS instrument (excluding beneficiary identifying information) as well as selected additional administrative variables. HOS PUFs are constructed to prevent the identification of any single beneficiary or plan and only respondents to the survey are included in the files. HOS PUFs are available at no cost and can be downloaded directly from this page (see below for additional information).

Medicare HOS Public Use Data Files

In order to facilitate the dissemination of data collected by the Medicare HOS project for additional research, PUFs have been created for each cohort of data. The files have been constructed in accordance with current CMS and Department of Health and Human Services (HHS) policies and other applicable statutes and laws. All identifying information has been excluded from the files, and demographic categories have been aggregated such that identification of any given individual is not possible.

Three distinct categories of PUFs have been generated:

1. Baseline PUFs contain the data collected during a given baseline survey administration.
2. Follow Up PUFs contain the data collected during the follow up survey administration which occurs two years after the baseline survey administration.
3. Analytic PUFs contain the merged baseline and follow up files as well as supplemental variables.

The PUFs are formatted as fixed-width ASCII (flat) files. The PUF ASCII files are bundled together (as a ZIP file) with additional documentation that details the construction and content of each PUF. SAS^® code is available that can be used to import the Analytic PUFs and create SAS^® data sets. Each import program creates a cohort specific SAS^® data set containing field names and labels. The link to download the SAS^® program is listed under the Analytic Data Import Code column in the PUF Data Files table.

The HOS PUF Data User's Guides are presented in the section entitled Data User's Guides. These Data User's Guides present detailed documentation regarding file construction and contents for all data sets distributed by this program. If you have any questions regarding the PUFs, please feel free to contact the Medicare HOS Information and Technical Support Line.

PUF Data Files

HOS COHORT	BASELINE DATA	FOLLOW UP DATA	ANALYTIC DATA	ANALYTIC DATA IMPORT CODE
COHORT 1	1998 ZIP, 5.8 MB	2000 ZIP, 2.7 MB	1998 - 2000 ZIP, 6.8 MB	SAS, 19 KB
COHORT 2	1999 ZIP, 6.8 MB	2001 ZIP, 2.6 MB	1999-2001 ZIP, 7.0 MB	SAS, 24 KB
COHORT 3	2000 ZIP, 7.0 MB	2002 ZIP, 2.5 MB	2000-2002 ZIP, 6.9 MB	SAS, 18 KB
COHORT 4	2001 ZIP, 4.3 MB	2003 ZIP, 2.3 MB	2001-2003 ZIP, 5.9 MB	SAS, 23 KB
COHORT 5	2002 ZIP, 3.9 MB	2004 ZIP, 2.1 MB	2002-2004 ZIP, 5.5 MB	SAS, 23 KB
COHORT 6	2003 ZIP, 4.0 MB	N/A*	2003-2005 ZIP, 5.3 MB	SAS, 23 KB
COHORT 7	2004 ZIP, 3.5 MB	N/A*	2004-2006 ZIP, 4.3 MB	SAS, 29 KB
COHORT 8	2005 ZIP, 3.5 MB	N/A*	2005-2007 Fall 2008	SAS Winter 2008
COHORT 9	2006 ZIP, 2.9 MB	N/A*	2006-2008 Fall 2009	SAS Winter 2009

*Beginning with Cohort 6, the PUF Follow Up data file is not being produced. The Follow Up sample is included in the PUF Analytic data file.

Medicare HOS Limited Data Sets and Research Identifiable Files

HOS LDSs and RIFs are comprised of the entire national sample for a given cohort (including both respondents and non-respondents), and contain all of the HOS survey items. The HOS LDSs include plan identifiers as well as several additional variables describing plan characteristics. They also contain protected beneficiary-level health information such as date of birth; however, specific direct person identifiers (i.e. name and health insurance claim number) are not included in LDSs.

The LDS File Specifications  (PDF, 622 KB) document details the characteristics of the Merged Baseline and Follow Up LDS for each available cohort of data. The documentation describes the field name/description, field type, field length, additional information (including valid values), and indication of field inclusion or exclusion for each cohort file.

The RIFs contain all of the variables in an LDS as well as specific direct person identifiers (i.e. name and health insurance claim number) that are not included in an LDS file. A signed Data Use Agreement with CMS is required to obtain either LDS or RIF data files. The Research Data Assistance Center (ResDAC) at the University of Minnesota is a CMS contractor that provides assistance to academic, government and non-profit researchers interested in using Medicare and/or Medicaid data. ResDAC is available to assist in the completion and/or review of data requisition forms for Medicare HOS research data files prior to their submission to CMS. For additional information and assistance with obtaining Medicare HOS LDS and RIF files, please visit the ResDac Medicare HOS Web page. ResDAC may also be contacted by calling 1-888-9RESDAC (1-888-973-7322) between the hours of 8am to 4:30pm CST Monday through Friday or by e-mailing resdac@umn.edu.