NHATS-CMS Linked Data Application Instructions and Guide

NHATS-CMS Linked Files are accessed through the NIA Data LINKAGE (LINKAGE) Enclave. The LINKAGE Enclave is a secure virtual desktop for accessing CMS data linked to NIA-funded studies. Data remain on the LINKAGE enclave servers and are accessed and analyzed by approved users virtually via a secure connection in an approved U.S. location and an approved device. 

The LINKAGE program requires approved NHATS projects to apply for and maintain a separate DUA with NIA. Projects are also held to rules and regulations of the LINKAGE enclave. Interested researchers should familiarize themselves with the requirements for a DUA with NIA prior to submitting an application to NHATS for linked CMS files.

Please note that all results requested for export outside of the enclave must be reviewed for disclosure risks by both LINKAGE and NHATS staff.

NHATS Files that are available to be linked with CMS files include: NHATS Public Files, NHATS Sensitive Files, and NSOC. 

Other NHATS files, such as the restricted geographic files, are not available to be linked with CMS files. 

Available CMS files are organized by calendar year and are available as shown in Table 1.

NHATS has four cohorts: 2011, 2015, 2022, and 2023. All NHATS participants in the 2011 and 2015 cohorts are included in all linked CMS files, although years of data vary due to factors such as length of enrollment in the Medicare program or death. Linkage of new NHATS participants added in 2022/2023 to their CMS records is forthcoming.

Requests may be made for specific years or for all years as indicated on the NHATS-CMS Linked Data Request Form.

In addition to specifying files and years of data, requestors select a file format: 

1. Standard format, which omits geographic and provider identifiers (meets the needs of most researchers), or 
2. Provider format, which omits geographic identifiers but includes provider identifiers (additional justification required). 

Table 1. CMS Files Available for NHATS in the LINKAGE Enclave

Linking to HRR & Restricted Tracker Files

External files available for linkage with NHATS-CMS linked data files include a file containing Hospital Referral Regions (HRR) linked to NHATS Sample Persons (SPs) and restricted tracker files that contain the date of the NHATS interview. These files will be made available to approved researchers in the LINKAGE enclave. For more information on how the HRRs were developed go to https://www.dartmouthatlas.org/data/. Note that HRR files can only be requested with Standard format CMS files only. At this time, contextual data (e.g., the area deprivation index) may not be linked to HRR.

Plans to link to the HRR or restricted tracker files should be specified in the applicant’s research plan and indicated in the HRR & Restricted Tracker Files Request Form. 

External File Linkages 

Users may request to bring other non-identifiable external files into the LINKAGE Enclave via an approved research plan, External File Request Form, and NHATS DUA. 

External file linkage – or imports – outside of code and documentation, need to be outlined in an approved research plan and documented in an External File Request Form. 

Investigator (Applicant) Requirements

To be eligible to apply for NHATS-CMS linked files, an Investigator must:

1. have a PhD or other terminal degree (e.g. MD-MPH) and hold a full-time faculty-level (or equivalent research) appointment at a U.S.-based university or research institution, 
2. be a U.S. citizen or permanent resident (this is an NIA requirement), and
3. be affiliated with an Institution that holds a Federal Wide Assurance (FWA) from the Office for Human Research Protection of the Department of Health and Human Services (see https://www.hhs.gov/ohrp/register-irbs-and-obtain-fwas/fwas/fwa-protection-of-human-subjecct/index.html)

Investigators collaborating at different institutions must have one Investigator at each institution who meets the qualifications to apply if both institutions are requesting access to the data through the LINKAGE enclave.

Pre‐doctoral students, post‐doctoral fellows, or clinical fellows interested in applying for access to NHATS-CMS Linked Files must have their mentor/advisor apply as the Investigator (applicant) and may be listed as Research Staff on the application.

Roles for NHATS-CMS Applications

• Investigator ‐ This individual is considered the Principal Investigator of the project and must meet all applicant requirements
• Co‐Investigator – This individual collaborates with the requesting Investigator and must hold a faculty‐level (or equivalent research) appointment at the Investigator’s institution
• Research Staff – This individual must have a formal affiliation with the Investigator’s institution and be under the supervision of the Investigator. Students and fellows, along with research staff, have this role.
• Receiving Agency Representative – This individual has authority to sign the NHATS Data Use Agreement (DUA) on behalf of the Investigator’s Institution. The representative must have the authority to bind the institution contractually and is typically found at the Investigator’s institution’s office of sponsored programs or projects.  

All Investigators, Co‐Investigators and Research Staff who will have access to the NHATS-CMS Linked Files on an NHATS DUA, must be registered NHATS users (see https://www.nhats.org/user/register), and must have a formal affiliation with the Investigator’s (applicant’s) institution.
 

A collaborating Investigator at another institution – or a collaborator who moves to a new institution – who wishes to gain or continue access to the NHATS-CMS Linked Files must submit a separate application to NHATS (see Application Process).

The individual will be designated the Investigator for their institution and must meet all Investigator requirements. They may include additional Co-Investigators and Research Staff from their institution on their application. All Investigators, Co-Investigators and Research Staff at collaborating institutions who will work with the NHATS-CMS Linked Files must be on the collaborating Investigator’s DUA, must be registered NHATS users (see https://www.nhats.org/user/register), and must have a formal affiliation with the collaborating Investigator’s institution.

Research team members who move institutions are required to notify NHATS prior to the move. A new DUA with the new institution is required to maintain access to NHATS restricted data. User accounts will be suspended until a new DUA is executed. 

Information on each required element of an application is discussed below.

Application Checklist
This form helps investigators keep track of the various elements required for the application. It also serves as an acknowledgement that the investigator (applicant) has ensured all research team members are registered NHATS users and that all research team members have read the rules regarding minimizing disclosure risk. 
Investigator Form
This form is needed for our database. Please note that any changes in the contact information listed on this form should be communicated to [email protected]. NHATS does not accept umbrella applications for networks, centers, or other coordinating efforts.
Project Forms and Documents
Project title and abstract
The project title, abstract, and research plan should reflect the same theme/aims for the project.
Research plan
Each application must state specific research aims and work scope to be performed. Detailed information on the study’s analytic sample, expected sample sizes, variables/constructs, and need for restricted data is required.

Research plans are reviewed for feasibility with respect to expected sample size and appropriateness of requested data to answer the research aims.

Applicants are encouraged to seek out information on the NHATS.org website to gain a sense of feasibility with respect to sample size. Applicants are also encouraged to read the restricted data disclosure minimization rules prior to submission of the research plan.  

CV or Biosketch for Investigator and Co‐Investigator(s)
Copy of full or expedited IRB approval 
IRB/Human Subjects approval at the Investigator’s institution should use standards for live human subjects. IRB approval must be at either the Full or Expedited level; access to these data does not qualify as exempt secondary analysis. A memo explaining the type of human subjects review that is being requested by NHATS and the reasons for it is provided for use as needed.

NHATS-CMS Linked Files Data Request Form
Data that are requested on any file request forms should be closely linked to the research plan.
External File Linkage Request Form (if applicable)
Any data files that will be imported into the enclave need to be documented on an external file request form. They should also be closely linked to the research plan.
HRR & Restricted Tracker Files Request Form (if applicable)
Signed copy of the NHATS Restricted Data Use Agreement (DUA)
Please read the DUA closely prior to signing. Principal investigators are not receiving agency representatives. Only research team members requesting enclave access need to be a party to the DUA. Research team members that do not need enclave access do not need to sign the DUA or other forms.
Signed NHATS Supplemental Restricted Data Use Agreement with Research Staff (if applicable)
Investigators Collaborating Across Institutions (if applicable)
Project Forms and Documents for each Investigator listed
Investigators collaborating at different institutions must each complete a separate application with a common title, file request form, and research plan.  A separate DUA and IRB approval (or proof that another institution serves as the IRB of record) is required for each institution. Only individuals at the applicant’s own institution should be listed as Co-Investigators, Research Staff or users on a given application.
List of Users Requesting LINKAGE Access
As of 6/6/25, all Principal Investigators must request access to the enclave. 
For each user:
NHATS Acceptable Use Policy
A Data Security Plan
Elements of the Data Security Plan:
Currently supported Operating System 
Anti-virus software (even for Macs)
Affirmation that the computer monitor position prevents eavesdropping (private office preferred)
A privacy screen if accessing the LINKAGE enclave from a shared office, a cubicle, or other shared workspace
The address from which connections to the Enclave will be made