Task 1: Describe the structure and location of the feasibility files: Medicare

A NHANES-CMS Medicare Feasibility Study file has been created for the Continuous NHANES data in two year survey intervals, beginning with 1999-2000. The range of years of NHANES to which Medicare records were linked is described in Course 2, Module 3, Task 2 “NHANES-CMS Linked Data Years of Availability”.  Each file contains a match status variable, CMS_MEDICARE_MATCH, to indicate whether linkage of the NCHS survey respondent to CMS Medicare records was possible based on linkage eligibility, and if so, whether the respondent was successfully matched to the CMS Denominator File for at least one year of the linkage interval.

CMS_MEDICARE_MATCH has three possible values:

For the remainder of this tutorial, the term “eligible for linkage” will refer to those individuals represented by both values “1” and “2.  “Ineligible for linkage” will refer to individuals represented by value “3”.

Each file also includes variables to indicate if a survey respondent has a linked data record for each of the seven CMS Medicare administrative record files (Denominator, MedPAR, Carrier, DME, HHA, Hospice, and Outpatient) and for each year of Medicare benefit coverage.

Possible values for this indicator are:

Structure

There is one feasibility file for each two-year Continuous NHANES data set. Each feasibility file has the same structure and number of variables.  The link to the feasibility file codebook that lists all variables for the file is located in the Resources section.

Location

The NHANES feasibility files are located under Data Linkage in the Data Access section of the NCHS website. They are ASCII DAT files that can be freely downloaded. 

Resources

• List of variables included in the NHANES 1999-2000 Feasibility File
• NHANES feasibility files
• Match Rate Table for NCHS-CMS Medicare Linked Data
• NHANES 1999-2000 Public Use Survey Data web pages
• Sample Counts for NCHS-CMS Medicare Linked Data
• NHANES 1999-2000 Demographic data codebook web page
• NCHS Data Linked to CMS Medicare Enrollment and Claims Files webpage
• Table showing sample size and unweighted linkage rates for linkages of NCHS surveys containing 1991-2001 Medicare Enrollment and Claims data and only 1999-2007 Medicare Enrollment and Claims data
• Table showing number of respondents linked to the Medicare files for each year (through 2007)
• Table showing percent of NCHS survey participants enrolled in managed care