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Enhancing Data Resources for Researching Patterns of Mortality in Patient Centered Outcomes Research

Linking the National Death Index to other sources to increase the availability of information on the cause of death.
  • Centers for Disease Control and Prevention (CDC) 
  • Food and Drug Administration (FDA)
  • Centers for Medicare and Medicaid Services (CMS) 
Start Date
  • CDC- 2/1/2017
  • FDA- 2/1/2017
  • CMS-3/1/2017


  • Use of Clinical Data for Research
  • Linking of Clinical and Other Data for Research
  • Use of Enhanced Publically-Funded Data Systems for Research


STATUS: Completed Project


National Center for Health Statistics (NCHS) worked with state offices to establish the National Death Index (NDI), which is a centralized database of death record information on file in state vital statistics offices. The NDI is a resource that helps epidemiologists and other health and medical investigators with their research. In particular, the NDI is used for mortality ascertainment to assess the causes and risk factors of diseases and conditions and for the effectiveness of a wide range of interventions and drug therapies.


Through collaboration between the CDC, CMS, and FDA, the overall goal of this project was to increase the availability of information on the cause of death by linking NDI data to other sources. Enabling linkages will allow researchers to develop national estimates of cause-specific death rates following emergency department (ED) visits and/or hospital stays for specific conditions.

The CDC objectives included:

  • Link the 2014 NHCS inpatient and emergency department (ED) claims data to the 2014 and 2015 NDI (to ensure at least 12 months of post-discharge follow up for each hospital event).

  • Link the 2014 CMS Master Beneficiary Summary File (MBSF) and Chronic Conditions Warehouse (CCW) to 2014 and 2015 NDI.

  • Link the 2016 NHCS inpatient and ED claims and EHR data to the 2016 and 2017 NDI.

  • Develop a long-term strategy for the access and use of NDI to support PCOR.

The FDA objectives include:

  • To develop standard, repeatable, and efficient technical solutions for linking the NDI’s death and cause of death data to large, commercially and publicly insured populations.

  • To demonstrate the feasibility of linkage by using use cases to assess associations between select medications and death or cause of death as an outcome.  

The CMS objectives include:

  • Purchase NDI data to link to Medicare decedents data from 2008-2016 and Medicaid decedents data from 2007-2015.

  • Link the NDI data on cause and manner of death with claims data to produce updated Medicare and Medicaid research files.


  • For the project “Adding Cause-Specific Mortality to the NHCS by Linking to the NDI,” the CDC project team produced linkages of patient EHRs and national mortality data. The project team also created new methods to optimize data linkages when using large national data files.

  • To develop a strategic plan for improving the NDI, the CDC project team surveyed state vital registration officials, conducted interviews with federal researchers, and held a NDI Workshop with state registration officials, Federal researchers, and academic researchers. After synthesizing findings, the CDC team convened a series of meetings with agency partners to discuss improving the NDI, resulting in the formation of a Federal Interagency Workgroup on Mortality Data System Improvement.

  • For the project “Pilot Linkage of National Death Index+ to Commercially and Publicly Insured Populations,” the FDA project team developed processes for matching patient records across the health plans and piloted a process for sharing data between multiple health plan databases, while protecting private health information. The team also conducted an analysis that demonstrated the usefulness of a standardized NDI linkage process to assess drug safety and effectiveness, adverse event surveillance, and comparative effectiveness research in distributed data networks.

  • As part of the project, “Enhancing Data Resources for Researching Patterns of Mortality in PCOR,” the CMS project team successfully linked the NDI’s death and cause of death data with the MBSF and the Medicaid Enrollee Supplemental File (MESF). The linked data have been used to probe a range of topic areas including cancer and blood disorders surveillance, mortality risk-factors for colorectal cancer, and diabetes surveillance.




  • The CDC project team published six research reports to demonstrate the utility of the linked dataset developed under the “Adding Cause-Specific Mortality to the NHCS by Linking to the NDI” project.

  • The FDA project team published a methods study protocol for the project “Pilot Linkage of National Death Index+ to Commercially and Publicly Insured Populations” in the Journal of Medical Internet Research. The publication is available here:



Below is a list of ASPE-funded PCORTF projects that are related to this project

Improving the Mortality Data Infrastructure for Patient-Centered Outcomes – Comprised of all U.S. mortality events since 1979, the NDI database allows researchers to match entries in the NDI to those participating in longitudinal clinical and epidemiologic studies to determine both fact and cause of death. A significant challenge with the NDI has been the lag between the date of death and the availability of the record for matching purposes. The CDC’s NCHS worked to improve the infrastructure to support more timely and complete mortality data collection through more timely delivery of state death records (e.g., cause of death) to the NDI database and through linking NDI records with nationally collected hospital datasets to obtain a more complete picture of patient care.