Health Related Behavior Study 2018 – Experiences During Deployment and Health of the Reserve Members

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The Health Behavior and Behavior Survey (HRBS) is the US Department of Defense's (DoD) primary survey of the health, health behaviors and well-being of military personnel. The HRBS, which has been conducted regularly for more than 30 years, covers areas that may affect military readiness or the ability to meet the demands of military life.

The Department of Defense commissioned the RAND Corporation to review and conduct the 2018 HRBS survey for active and reserve military personnel. This report examines the results of the Reserve portion of the survey.

This report examines deployment experiences and health outcomes. Some results are also compared to the Health Promotion 2020 (HP2020) goals for the US population set by the US Department of Health and Human Services.

Because the armed forces are significantly different from the population (for example, members of the armed forces are more likely to be young and male than the population), these comparisons are presented for comparative purposes only.

Deployment Duration and Frequency

The 2018 HRBS survey included several questions asking respondents to share their experiences with deployment. These included the number of times respondents were deployed and the duration and experience of deployments.

Across all units, 52.9 percent (confidence interval [CI]: 51.7-54.1) of respondents reported at least one previous deployment, including combat deployments and other deployments. The majority had been deployed more than once, and 18.6% (CI: 17.9-19.3) had been deployed at least three times.

For those who had been on secondment, the total length of secondment varied widely. At one extreme, 13.5% (CI: 12.6-14.5) had been posted for up to six months and at the other extreme, 6.7% (CI: 6.1-7.2) for more than 48 months. Overall, 60.0 percent (CI 58.7-61.2) of those who had ever been posted had been posted for a total of 7-24 months. Of those who had been posted, 66.7 percent (CI 65.4-68.0) had not been posted in the past year.

Deployment While Combat

Those who had been deployed also had different experiences of combat operations. Of all personnel, 80.3 percent (CI 79.2-81.5) had been in combat at least once. Of all personnel, 41.2 percent (CI: 39.9-42.5) reported having had a traumatic experience in combat, such as working with landmines, seeing members of their unit or allied unit seriously wounded or killed, or being wounded in combat at some point during their deployment.

The four most common traumatic experiences were: encountering a person killed in action (25.2% CI 24.1-26.3), witnessing the death or serious injury of a member of their unit or allied unit (23.1% CI 22.0-24.2), witnessing the death or serious injury of civilians (23.1% CI 22.0-24.2) and working with landmines or other unexploded ordnance (11.2% CI 10.3-12.0).

Mental and Psychological Health

In the HRBS, respondents were asked about various mental health indicators. General mental health was assessed using the Kessler Mental Health Scale 6 (K6), a commonly used measure of non-specific severe psychological distress. The K6 scale is designed to distinguish between anxiety that indicates a psychiatric disorder that would be recognized and treated by a clinician, and anxiety that is commonly experienced but does not indicate a clinical condition.

The HRBS also included questions that indicated the likely presence of post-traumatic stress disorder (PTSD), as well as questions about sleep quality. The proportion of newly hired workers (8.0%, CI: 6.6-9.3) – i.e., those who had entered the workforce in the past 12 months – who reported severe stress in the past 12 months on the K6 questionnaire was significantly lower than non-employees (11.3%, CI: 10.4-12.3).

In addition, significantly fewer recent workers (4.7% CI 3.7-5.8) than non-recent workers (6.8% CI 6.1-7.6) reported severe stress in the last 30 days on the K6 questionnaire. There were no statistically significant differences between recent and non-recent reports in the proportion who reported no, low or moderate stress in the last 12 months or 30 days.

Those with recent deployment were significantly less likely to report probable PTSD (10.7%, CI 9.2-12.2) than those without recent deployment (16.3%, CI 15.3-17.4). Recent posters (13.5%, CI: 11.7-15.2) were significantly less likely than non-posters (16.3%, CI: 15.3-17.4) to report sleeping “very well” in the past 30 days, but there were no statistically significant differences between recent posters and non-posters who reported sleeping “fairly well”, “fairly poorly” or “very poorly”.

Physical Health During Deployment

The HRBS asked respondents whether they had experienced body pain in the past 30 days, traumatic brain injury (TBI) in the past 12 months, or post-concussion symptoms in the past 30 days, and asked them to rate their health status.

Recently employed workers were significantly more likely to report body pain, mild TBI and post-concussion symptoms. There were no statistically significant differences in self-assessment between newly employed and non-employed workers.


The HRBS provides information on the relationship between reservists' deployment and their physical and mental health. Understanding this relationship is important because active duty soldiers are often deployed more than once during their careers, and the negative effects of deployment on health and health-related behaviors can affect readiness for future deployments.

The majority of 2018 HRBS respondents have experienced at least one deployment since joining the military. Exposure to combat trauma was also common. Less recently deployed than non-deployed reported severe stress, but a higher proportion of recently deployed than non-deployed reported pain, mild TBI, and post-concussion symptoms.


RAND conducted the 2018 HRBS survey among active duty and reserve US military personnel from October 2018 to March 2019. The reserve component of the survey included five reserve military personnel – Air Force, Army, Marine Corps, Navy, and Coast Guard – and two National Guard personnel – Air National Guard and Army National Guard.

The 2018 HRBS was a confidential online survey that allowed researchers to target reminders to non-respondents and reduce survey burden by linking responses to administrative data. A stratified random sampling method was used to select the sample by grade level, grade and gender.

The overall weighted response rate to the survey was 9.4%, resulting in a final analytical sample of 16,475 responses for the Reserve. To deal with missing data, RAND researchers used imputation, a statistical procedure that uses available data to estimate missing values.

To represent the reserve population, responses were weighted to account for over-selection of service members in certain sections. Point estimates and 95% CIs are presented in this survey report.

RAND researchers controlled for differences in each outcome between key factor levels or subgroups (service area, salary level, gender, race/ethnicity, and age group) using a two-step procedure based on the Rao-Scott chi-square test to determine overall differences in individual factor levels, and if the overall test was statistically significant, a two-sample t-test to examine all possible pairwise comparisons between factor levels (e.g., men vs. women).

Readers interested in these differences should consult the full final report of the HRBS 2018 Reserve Component. This report is one of eight reports on the Reserve; this report and six of the other seven reports all correspond to different chapters in the full report, and the eighth report provides an overview of all findings and policy implications. Eight similar reports deal with the results of the active component.

Limitations and Restrictions

The response rate is considered low for a survey. Although a low response rate does not automatically mean that the survey data are biased, it does increase the likelihood of bias. As with any self-report survey, social desirability bias is possible, especially for sensitive questions and topics. For some groups representing a small percentage of the total military population, survey estimates may be inaccurate and should be interpreted with caution.

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