CSP #505: Millennium Cohort Study - VA Cooperative Studies Program (CSP)
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CSP #505: Millennium Cohort Study


Investigator Access

What's available?

Research data

  • Questionnaire data: De-identified, self-reported, individual participant data collected during the 5 survey cycles (2001, 2004, 2007,2011, 2014). (SAS format)
  • DoD records: Department of Defense (DoD) Defense Manpower Data Center (DMDC) individually-identifiable data, demographic data, and electronic military personnel data, and Military Health System Data Repository (MDR) data. (SAS format)
  • VA records: Electronic health, benefits, and disability records (EHR) on all Millennium Cohort Study participants who have VA records. (SAS format, available mid-2019)

Available Documentation 

Data dictionary (PDF format) 

Dates Data are Available 

  • Questionnaire data: Currently available, no end date
  • DoD records: Currently available, no end date
  • VA records: Outpatient data available, inpatient data estimated for end of 2020

Access Criteria 

VA investigators: To request access to data, interested VA investigators should  submit a Research Resource Request form to the CSP #505 Project Manager at Amber.Banerjee@va.gov. CSP #505 will review initial requests and will provide the VA investigator with the study proposal to describe the proposed analyses. The proposed analyses will be reviewed by the VA’s CSP #505 Executive Committee and NHRC’s Millennium Cohort Study scientific review committee. Projects will be prioritized based on scientific merit. For proposals that are designated to move forward, the VA investigator will scientifically lead the project and paper, while all data analyses will occur at NHRC by NHRC study staff under the direction of the VA investigator.   

Non-VA investigators: Visit Research Collaborations1 study webpage or contact DoD.MillenniumCohortPI@mail.mil for more information. 

Study Characteristics


This study evaluates any long-term health effects of military service, including deployments. The original objectives included building a cohort of ~150,000 and assessing chronic diagnosed and subjective health problems among military members, in relationship to exposures of military concern. 

Era of Service

Primarily Gulf War, Operation Enduring Freedom (OEF), Operation Iraqi Freedom (OIF), Operation New Dawn (OND)


U.S. military personnel (active duty, Reserves, and National Guard) serving in the Army, Navy, Coast Guard, Air Force, and Marine Corps from October 1, 2000 - present

Study Design 

Prospective cohort study

Time Period 

2001 - 2068

Participants surveyed every 3 years over a 67-year period.




≥200,000 for all 4 panels enrolled in 2001, 2004, 2007, and 2011

Response Rate

  2001 2004 2007 2011 2014 
Panel 1 77,047 (35.9%) 55,021 (71.4%) 54,790 (71.1%) 51,678 (67.1%)

 51,156 (68.4%)

Panel 2 N/A 31,110 (21%) 17,152 (55.1%) 15,149 (48.7%)  14,800 (48.2%)
Panel 3 N/A N/A 43,439 (22%) 22,071 (50.8%)  20,000 (46.4%)
Panel 4 N/A N/A N/A 50,052 (20%)  27,236 (54.5%)

Recruitment Method    

A probability-based sample of active-duty, Reserve, and National Guard members from all services was constructed by the DMDC. Individuals are contacted via mail or email and invited to complete a study questionnaire either on the paper copy received in the mail or through the online version.


Variable over time with maximum value of $5 in form of t-shirt, coin, hat, or gift card

Data Collected

  • Demographic and military-specific data obtained from electronic personnel files maintained by DMDC
  • Study questionnaire1 collects data on a broad range of topics such as general health, health behaviors, health conditions/symptoms, health care utilization, military and combat history, and potential exposures.

Data Collection Methods

Survey data collected via structured questionnaire, mailed or online, with linkage to medical records and other databases for active duty personnel (e.g., inpatient, outpatient, pharmaceuticals, vaccination information, and mortality data) and with linkage to VA records for separated personnel in the VA system.

Funding Source

Department of Defense through the US Army Medical Research Materiel Command (USAMRMC) Military Operational Medicine Research Program (MOMRP)


CSP #505 Project Manager: Amber.Banerjee@va.gov
CSP #505 Study Chair: Edward.Boyko@va.gov

Selected Publications

Gray GC, Chesbrough KB, Ryan MA, Amoroso P, Boyko EJ, Gackstetter GD, Hooper TI, Riddle JR; Millennium Cohort Study Group. The millennium Cohort Study: a 21-year prospective cohort study of 140,000 military personnel. Mil Med. 2002 Jun;167(6):483-8.

Smith TC, Millennium Cohort Study Team. The US Department of Defense Millennium Cohort Study: career span and beyond longitudinal follow-up. J Occup Environ Med. 2009 Oct;51(10):1193-201.

Crum-Cianflone NF, Naval Health Research Center San Diego CA. The Millennium Cohort Study: Answering Long-Term Health Concerns of US Military Service Members by Integrating Longitudinal Survey Data with Military Health System Records. Part 2. Pre-Deployment. 2013 Jan. 

Porter B, Bonanno GA, Frasco MA, Dursa EK, Boyko EJ. Prospective post-traumatic stress disorder symptom trajectories in active duty and separated military personnel. J Psychiatr Res. 2017 Jun;89:55-64. 

Additional publications1

More Information

Millennium Cohort study website1

August 2018 VA Research Currents newsletter article: Data-sharing milestone


1 This link takes you to a non-U.S. government website. VA isn't responsible for the content or privacy policies on that site and doesn't endorse the content or its sponsor.