Seattle Epidemiologic Research and Information Center (ERIC)

CSP #505: Millennium Cohort Study

CSP #505 uses data from the Department of Defense’s (DoD) Millennium Cohort Study¹ (MCS) and VA health care and benefits records to create resources that present a more complete picture of the military to civilian life cycle experienced by Veterans. These records were first linked in 2018 and are updated on a regular basis. This data can be used to identify potential causes of military, Veteran, and national healthcare problems, especially those stemming from military service and military exposures, and to inform innovative and effective solutions.

Impact

Findings have informed DoD and VA policy, federal legislation, and clinical practice guidelines in VA, DoD, and civilian care settings. This includes adding asthma, rhinitis, and sinusitis to the list of VA presumptive conditions for exposure to fine particulate matter. Federal, VA, and DoD materials that reference MCS publications include: 

• VA/DoD clinical practice guidelines for mental health conditions, headache, chronic multi-symptom illness (CMI), and asthma
• National Academies reports on tobacco use, readjustment needs of Veterans, PTSD treatment, and the Airborne Hazards and Open Burn Pit Registry (AHOBPR)
• DoD policies regarding women’s health, mental health and suicide, substance use, and occupational health and safety including the establishment and implementation of the circadian-based watch bill

One of largest impacts are the longstanding and ongoing contributions made to the DoD’s Sexual Assault Prevention and Response (SAPR) program.

PACT Act research

In 2022 the VA Under Secretary tasked CSP #505 to respond to Section 504 of the Sergeant First Class Health Robinson Honoring Our Promise to Address Comprehensive Toxics Act of 2022 (PACT Act). This is being completed through a longitudinal study on the health trends of Veterans who served in the Armed Forces after September 11, 2001. The work will take place over 5 years in collaboration with the DoD’s Naval Health Research Center (NHRC). Study topics include mental health, physical health, health behaviors, military and occupational exposures, and quality of life.

Current projects include research examining PTSD and Major Depressive Disorder, diabetes and stress, neurodegenerative diseases, respiratory disease, and the possible effects of air pollution and other exposures on physical health.

The goal of our PACT Act research is to provide insight into the health trends of post 9/11 Veterans to better understand risk and protective factors in this population, guide future research, inform policy making and health care decisions, and improve the quality of life for Veterans and service members long-term. 

Staff

Study Chair: Edward J. Boyko, MD, MPH - Edward.Boyko@va.gov
Project Manager: Lynne Liu, MPH - Lynne.Liu@va.gov  
Epidemiologist: Sahra Mohazzab-Hosseinian, MS, PhD
Epidemiologist: Mario Trejo, MPH, PhD 
Data Analyst: Elaine Hu, MS 
Data Analyst: Lexie Schmidt, MPH
Research Coordinator: Nicole Riedel, MPH
Research Coordinator: Jacob Armitage, MS 

Select publications

Castañeda SF, Belding JN, Kolaja CA, LeardMann CA, Jacobson IG, Rivera AC, Carey FR, Boparai S, Walstrom JL, Sheppard BD, Boyko EJ, Ryan MAK, Rull RP; Millennium Cohort Study Team. Cohort Profile Update: The US Millennium Cohort Study-evaluating the impact of military experiences on service members and veteran health.¹ Int J Epidemiol. 2023 Aug 2;52(4):e222-e231. doi: 10.1093/ije/dyad088. PMID: 37348866.

Belding JN, Castañeda SF, Jacobson IG, LeardMann CA, Porter B, Powell TM, Kolaja CA, Seelig AD, Matsuno RK, Carey FR, Rivera AC, Trone DW, Sheppard B, Walstrom J, Boyko EJ, Rull RP, The Millennium Cohort Study: The First 20 Years of Research Dedicated to Understanding the Long-Term Health of US Service Members and Veterans.¹ Ann Epidemiol. 2021 Dec 11;67:61-72. doi: 10.1016/j.annepidem.2021.12.002. Online ahead of print. PMID: 34906635.

A summary of all publications is available at Millennium Cohort Study: Publications.¹

Request access to data

Qualified researchers can request access to the merged Millennium Cohort – VA data for secondary data analysis. Data access is managed by CSP #505 staff in collaboration with the Millennium Cohort Study team at the DoD Naval Health Research Center (NHRC). 

After the initial access request, researchers are required to submit a study proposal. Those are reviewed on a quarterly schedule.

Cyberseminars

• Millennium Cohort Family Study: The Impact of Military Life (05-03-2023) is available on the VA intranet. If you have VA network access, copy this link into your browser: https://vaww.hsrd.research.va.gov/for_researchers/cyber_seminars/archives/video_archive.cfm?SessionID=6338
• Department of Defense Birth and Infant Health Research Program: An Overview (03-28-2023) is available on the VA intranet. If you have VA network access, copy this link into your browser: https://vaww.hsrd.research.va.gov/for_researchers/cyber_seminars/archives/video_archive.cfm?SessionID=6287
• Research on Active Duty Servicewomen and Women Veterans: Research Opportunities using the Millennium Cohort (01-11-2021) is available on the VA intranet. If you have VA network access, copy this link into your browser: https://vaww.hsrd.research.va.gov/for_researchers/cyber_seminars/archives/video_archive.cfm?SessionID=3908
• Overview of the Millennium Cohort Study (MILCO): Opportunities for VA Investigators (10-29-2020) is available on the VA intranet. If you have VA network access, copy this link into your browser: https://vaww.hsrd.research.va.gov/for_researchers/cyber_seminars/archives/video_archive.cfm?SessionID=3878

DoD Millennium Cohort Study origin

The need for a prospective, longitudinal cohort study of military services members became apparent following the first Gulf War, when the lack of baseline data was a serious limitation to designing studies to assess Gulf War Illness. 

The MCS was included in the 1999 Strom Thurmond National Defense Authorization Act at the recommendation of several national agencies, including VA, DoD, the Armed Forces Epidemiological Board, and the Institute of Medicine. It established “a longitudinal study to evaluate data on the health conditions of members of the armed forces upon their return from deployment.” 

DoD Millennium Cohort Study overview

The MCS launched in July 2001 and is conducted at the Naval Health Research Center in San Diego, CA. Study participation includes completing comprehensive questionnaires about health, lifestyle, and military experiences around every three years. Questionnaire data is then linked with other data sources. The study plans to continue longitudinal follow-up and triennial data collection on participants for 67 years.

As of 2021, more than 250,000 study participants have enrolled in the study over the course of five enrollment panels. Initial participants were sampled from a cross-section of the entire military and included oversampling for women, Reservists, and those who had previously deployed to the conflicts in Bosnia, Kosovo, and SW Asia (the most recent deployments at that time).

Subsequent enrollment panels have focused on newer accessions to the military, while oversampling for women and Marines. The heightened operational tempo since the September 11, 2001 terrorist attacks precluded the need to oversample for deployers and Reservists in later enrollment panels. 

The MCS expanded in 2011 to include the Millennium Cohort Family Study¹. The Family Study has enrolled around 30,000 participants across two panels since its inception. 

Looking to the future

Recent developments increase the value of MCS for research on Veteran health issues. 

• The 2024 renewal of the data sharing agreement between CSP #505 and NHRC allows for continued bilateral transfer of data. The enables researchers to conduct studies using health and benefits data from VHA paired with self-reported conditions, exposure assessments, Deployment Manpower Data Center (DMDC) service information, and Military Health System (MHS) Data Repository (MDR) health data.
• A CSP #505 Data Repository is being developed to host MCS data on VA servers. This enables more VA researchers to conduct studies with both VA and MCS data.
• The Veteran Survey Module tailored to collect information relevant for the Veteran population debuted on the 2024 follow-up survey and data collection is in progress. This new module is being improved and modified by VA and DoD teams for use in the 2027 survey cycle.
• The expansion of the Millennium Cohort Family Study was announced in 2021 and include a survey of adolescents and their parents, the Study of Adolescent Resilience (SOAR).¹ SOAR enrolls teens and parents to represent all branches and components of the military. The study was in the final stages of its first wave of data collection in 2023. 

Executive Committee

The Executive Committee is the decision-making group who reviews and makes recommendations on all proposed study changes, use of study data, potential publications, and other operational parts of the study.

• Aaron Schneiderman, PhD, MPH – Director, Epidemiology Program, Health Outcomes of Military Exposures (HOME)
• Dawne Vogt, PhD, MA – Research Psychologist, Women’s Health Sciences Division of the National Center for PTSD
• Mary Jo Pugh, PhD, MA – Career Research Scientist, Health Services R&D (HSR&D) Center of Innovation (COIN): Informatics, Decision-Enhancement and Analytic Sciences Center
• Rudolph Rull, PhD, MPH – Principal Investigator, Millennium Cohort Study
• Paul Shekelle, MD, PhD, MPH – Staff Physician, VA Greater Los Angeles Healthcare System

Ex Officio members

• Edward Boyko, MD, MPH - CSP #505 Study Chair
• Lynne Liu, MPH - CSP #505 Project Manager
• Victoria Davey, PhD, MPH - Associate CRADO for Epidemiology and Public Health
• Grant Huang, PhD, MPH - Deputy Chief of Research and Development Officer - Enterprise Optimization; Director - Cooperative Studies Program
• Nicholas L. Smith, PhD, MPH – Director, CSP #505 Coordinating Center, Seattle ERIC

CSP #505 Executive Committee meeting attendees (September 2023)
From left to right: Edward Boyko, Judith Harbertson, Neika Sharifian, Shauna Frank, Aaron Schneiderman, Felicia Carey, Elaine Hu, Lynne Liu, Sheila Castaneda, Nick Smith, Rudolph Rull, Mary Jo Pugh, Dawne Vogt, William Culpepper, Paul Shekelle, Grant Huang

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

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