Millennium Cohort: enrollment begins a 21-year contribution to understanding the impact of military service

The Physical and Mental Health of A Large Military Cohort: Baseline Functional Health Status of the Millennium Cohort

“…The study population consisted of US military personnel proportionately more likely to be: 35 or older, college educated, married, White non-Hispanic, in service more than 8 years, and in the officer ranks (Table 1). Chi-square tests of association suggest statistically significant differences in composition between the 2000 US military, the invited Cohort and the Cohort members, although much of the difference is due to the sampling strategy employed [16]. Table 2 reports the unadjusted means for the MCS and PCS scores stratified by gender.…”

“…Although participants self-selected in accepting the invitation to become part of the cohort reports of Millennium Cohort baseline data suggest a representative sample of military personnel measured by demographic and health characteristics and reliable health, vaccination, and deployment reporting [16,[25][26][27][28][29][30][31]. Due to the Cohort being constructed to sample more women, those with recent deployment experience to Southwest Asia, Bosnia, or Kosovo, and Reserve/ National Guard, there are compositional differences between the target population and those in military service in October 2000 [16]. However, as demonstrated by the slight difference in weighted means and nonweighted means, these proportional differences have minimal impact when generalizing to the US military.…”

“…The Millennium Cohort Study Panel 1 consists of 77,047 consenting military service members who were enrolled using a modified Dillman approach [24] and offered both Web and US postal-based submission options (36% response rate of those invited to participate) [16]. The invited Cohort was sampled from electronic personnel records representing approximately 11.3 percent of the 2.2 million men and women in service as of October 1, 2000.…”

“…Investigation of potential biases in the Millennium Cohort Study have found no differences in healthcare utilization, as measured by hospital encounters and outpatient care, prior to study invitation as a determinant for enrollment (data not yet published). Investigation of Millennium Cohort self-reported data have been found reliable in test re-test investigations and when comparing to electronically maintained databases and to have high internal consistency within standardized instruments [16,[25][26][27][28][29][30][31]. This research has been conducted in compliance with all applicable federal regulations governing the protection of human subjects in research and was reviewed by the Naval [32].…”

“…The Millennium Cohort Study was launched in October 2000 [16], in response to the US Department of Defense recommendation for a coordinated effort to study the potential health effects of deployment-related exposures [17], and the Institute of Medicine recommendation for a systematic, longitudinal, population-based assessment of service members' health [18]. The Cohort began enrollment for the 21- This report investigates the baseline mental and physical health status of this large military cohort, as measured by the Medical Outcomes Study Short Form 36-item Survey for Veterans [19].…”