VA Cooperative Studies Program (CSP)

Investigator Access

What's Available

Research data

• Questionnaire data: Self-reported, individual participant data collected during the 6 available survey waves (2001, 2004, 2007, 2011, 2014, 2019). (SAS format)
• Department of Defense records: Defense Manpower Data Center (DMDC) electronic military personnel data and Military Health System (MHS) Data Repository (MDR) data (2000-current). (SAS format)
• VA records: Electronic health, benefits, administrative, and disability records for all Millennium Cohort Study (MCS) participants who have VA records. (SAS format)
  

Dates Data are Available 

• Questionnaire data: Currently available, no end date
• DoD records: Currently available, no end date
• VA records: Currently available, no end date

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 Lynne.Liu@va.gov. Investigators whose request forms are approved by CSP #505 and Naval Health Research Center (NHRC) are invited to submit a Secondary Data Analyses Proposal. The Secondary Data Analyses Proposal will be reviewed by the CSP #505 Executive Committee and NHRC Scientific Review Committee. For approved proposals, the VA investigator will scientifically lead the project and paper, while data analyses may be performed in one of the following ways:

1. Analyses performed at NHRC by study staff under the direction of VA investigator
   
     a. VA investigator doesn’t have direct access to the individual-level data
     b. May not require a Data Use Agreement (DUA) between CSP #505 and the VA investigator’s institution
   
   
2. Analyses performed at VA by VA investigator/investigator’s data manager/analyst 
   
     a. VA investigator has direct access to the individual-level data
     b. DUA required between CSP #505 of the VA investigator’s institution
     c. VA investigator must be capable of performing data management activities and analyses, or providing their own data manager/analyst 
   

Non-VA investigators: Non-VA investigators may also submit a Research Resource Request form to the CSP #505 Project Manager at Lynne.Liu@va.gov. Approved request forms will be invited to submit a Secondary Data Analyses Proposal template which must be approved by the CSP #505 Executive Committee and the NHRC Scientific Review Committee. Visit Research Collaborations¹ study webpage or contact DoD.MillenniumCohortPI@health.mil for more information. 

Study Characteristics

Objectives

This study investigates the long-term health effects of military service by capturing the entirety of the military life cycle from entry into service to transition back into civilian life as a Veteran. The cohort now includes more than 260,000 servicemembers, more than 65% of whom are Veterans. 

Eras of Service

Primarily post-9/11 conflicts, including Operation Enduring Freedom (OEF), Operation Iraqi Freedom (OIF), and Operation New Dawn (OND); first enrollment panel includes previous eras (e.g., 1990-1991 Gulf War).

Population

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

As of 2024, 69% of Millennium Cohort Study participants were male and 59% were non-Hispanic white. Approximately 43% of participants were current or former members of the Army, 31% Air Force, 15% Navy, and 9% Marine Corps, and 2% Coast Guard; more than 65% of survey participants are Veterans. Over 27% of participants deployed at least once during their military service. At the time of study enrollment, 58% of participants were junior enlisted personnel, 26% were senior enlisted, and 17% were officers.

Study Design 

Prospective cohort 

Time Period 

2001 - 2068

Participants surveyed every 3-5 years over a 67-year period.

Setting

Predominantly in the United States, although some participants were stationed, deployed or lived overseas.

N

>260,000 for all 5 panels enrolled in 2001, 2004, 2007, 2011, and 2020.

Response Rate

For more information, please see: https://www.millenniumcohort.org/about¹

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. A modified-Dillman approach is implemented using mailed postcards and email reminders to increase response rate among participants.

Compensation

Nominal incentives provided (variable over time) with a maximum value of $5 in the form of a 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 actively serving personnel (e.g., inpatient, outpatient, pharmaceuticals, vaccination information, and mortality data) and with linkage to VA records for personnel in the VA system.

Funding Sources

• Department of Defense through the Defense Health Program
• VA Cooperative Studies Program
• VA Health Outcomes Military Exposures

Investigators

• MCS Principal Investigator: Rudolph P. Rull, PhD, MPH
• CSP #505 Study Chair: Edward J. Boyko, MD, MPH

Contact 

• CSP #505 Project Manager: Lynne.Liu@va.gov
• CSP #505 Study Chair: Edward.Boyko@va.gov

Selected Publications

Kolaja CA, Belding JN, Boparai SK, Castañeda SF, Geronimo-Hara TR, Powell TM, Tu XM, Walstrom JL, Sheppard BD, Rull RP; Millennium Cohort Study Team. Survey response over 15 years of follow-up in the Millennium Cohort Study. BMC Med Res Methodol. 2023 Sep 9;23(1):205. doi: 10.1186/s12874-023-02018-z. PMID: 37689640.

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. 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 BD, Walstrom JL, Boyko EJ, Rull RP, Millennium Cohort Study Team. The Millennium Cohort Study: The first 20 years of research dedicated to understanding the long-term health of US Service Members and Veterans. Ann Epidemiol. 2022 Mar;67:61-72. doi: 10.1016/j.annepidem.2021.12.002. PMID: 34906635.

Additional publications¹

More Information

Millennium Cohort Study website¹

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