Health Related Behavior Study 2018 – Health Promotion and Disease Prevention within the Reserve Components

The Health 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 for the Reserve.

This summary examines results for physical activity, body weight, screen time, annual physical assessment, health insurance status, sleep health, and substance use for waking hours. Some of the HRBS results are also compared to the Healthy People 2020 (HP2020) goals set by the US Department of Health and Human Services for the US population.

Because military personnel are significantly different from the general population (for example, military personnel are more likely to be young and male than the general population), these comparisons are presented for comparative purposes only.

Be physically active

Military personnel have physical fitness requirements that are designed to promote physical fitness as it is essential for force readiness. Poor physical fitness is associated with injuries and chronic diseases that can have a negative impact on military readiness.

Physical fitness has also been linked to mental stamina and physical endurance. The HP2020 sets goals for moderate physical activity (MPA), vigorous physical activity (VPA) and strength training for the US population. These targets include

• At least 47.9% of the population engaging in at least 150 minutes of moderate physical activity per week or at least 75 minutes of vigorous physical activity per week.
• At least 31.3 percent engage in MFA for more than 300 minutes per week or in occupational recreation for at least 150 minutes per week.
• At least 24.1% engage in muscle strengthening activities two or more days a week.

The 2018 HRBS showed that Reserve members were favorable on all of these standards. Of Reserve members, 67.2% (confidence interval [CI]: 66.1-68.3) reported doing at least 150 minutes per week of MPA or at least 75 minutes per week of VFA, and 41.6% (CI: 40.4-42.8) reported doing at least 300 minutes per week of MPA or at least 150 minutes per week of VFA.

In addition, 43.1% (CI: 41.9-44.3) of reservists reported doing strength training at least three days a week. The proportion of reservists who reported exercising at least three days per week exceeded the HP2020 target of exercising twice per week.

Weight

Nearly 40% of the US population is classified as obese, which increases the risk of premature mortality and several chronic diseases. The HP2020 initiative sets weight targets for adults aged 20 years and older based on the following Centers for Disease Control and Prevention body mass index (BMI) categories.

• Underweight: less than 18.5 kg/m2.
• Normal weight: 18.5-24.9 kg/m2 (HP2020 target: at least 33.9% of the population).
• Overweight: 25.0-29.9 kg/m2
• Obese Overweight: 30 kg/m2 or more (HP2020 target: 30.5% or less of the population).

It is important to note that BMI is an indirect measure of body fat, and more muscular members may have been misclassified as overweight or obese.

Overall, the 2018 HRBS survey found that 31.4% (CI: 30.2-32.5) of reservists aged 20 years or older were of normal weight. This is roughly comparable to the HP2020 target of 33.9% of those aged 20 years or older being of normal weight.

In addition, 19.0% (CI 18.1-20.0) of the reserves were obese. Even if the military meets the HP2020 target of no more than 30.5% of people aged 20 and over being obese, the proportion of overweight soldiers may still be a cause for concern. However, as we have noted, very muscular individuals may be misclassified as overweight or obese based on conventional BMI thresholds.

Time in front of the Screen

Screen time, whether on a desktop or laptop computer, TV, smartphone, tablet, other portable device or games console, is usually sedentary. It is therefore associated with an increased risk of obesity and mortality. In fact, studies show that screen time is a risk factor for many cardiovascular diseases and mortality, regardless of how much time is spent exercising.

In the 2018 HRBS study, 65.4 percent (CI: 64.3-66.6) of reservists reported spending one to four hours per day screen time, and 26.4 percent (CI: 25.3-27.5) reported spending five or more hours per day screen time. Although there were no significant differences in screen time between sections, the lowest sections were most likely to report spending five or more hours per day in front of a screen.

Annual Medical Exams

Routine physical examinations can detect asymptomatic conditions, intervene early and promote healthy behaviour. These screenings have been shown to save lives through early detection of cancer and chronic diseases and to save money. In the armed forces, all service personnel are required to undergo annual health checks. These examinations are called periodic health checks and are also used to assess individual capabilities.

In the 2018 HRBS survey, respondents were asked if they had had a routine health check in the last 12 months. Routine check-ups referred to a general medical examination rather than an examination for a specific injury, illness or condition. Overall, 71.6% (CI: 70.4-72.7%) of reservists reported having had such a check-up.

Status of Health Insurance

The proportion of uninsured people in the United States has declined steadily over the past decade, largely due to the Affordable Care Act. In 2018, 91.5% of Americans had public or private health insurance[2], but this is still far from the HP2020 goal of 100% of Americans having some form of health insurance.

The health insurance situation is particularly important for reservists, as active duty service members generally do not have access to DOD health care, and delays in obtaining health care due to lack of insurance can jeopardize medical capability.

Overall, 92.0% (CI 91.1-92.8) of reservists reported having some form of health insurance. This figure is lower than the HP2020 target, but comparable to the population as a whole. Reservists in lower ranks were less likely to report having health insurance.

Sleep 

The HP2020 plan defines adequate sleep as at least seven hours of sleep per day for U.S. adults aged 22 and older and eight hours per day for adults aged 18-21. Lack of adequate sleep is associated with daytime sleepiness, fatigue, diabetes, cardiovascular disease, obesity and depression.

In the 2018 HRBS survey, respondents were asked how much sleep they got on average over 24 hours in the past 30 days, how sleep affected their energy levels and whether they used sleeping pills or prescription drugs.

Across all arms, 45.4% (CI 44.2-46.6) of respondents met the HP2020 standard for adequate sleep. This is down from 68.3% of Americans who follow sleep guidelines and the HP2020 target of 72.8% of Americans who follow guidelines.

In addition, 19.0 percent (CI: 18.1-19.9) of reservists reported having a moderate to severe energy deficit due to insomnia, and 6.2 percent (CI: 5.6-6.7) reported using prescription or over-the-counter medications at least three days a week in the past 30 days.

Use of drugs to maintain wakefulness

Caffeine drinks, over-the-counter and prescription drugs can increase stamina and facilitate anaerobic activity. They can also have negative effects such as sleep disturbance, anxiety and palpitations.

In the 2018 HRBS survey, respondents were asked to report how often they had used energy drinks, over-the-counter medicines and prescription drugs in the past 30 days to stay awake. Overall, 11.4% (CI: 10.6-12.2) of reservists reported using energy drinks at least three times a week in the past 30 days to stay awake.

Few reported using medication to stay awake: 1.2% (CI 0.9-1.5) of reservists reported using over-the-counter medication at least three times a week in the past 30 days to stay awake, and 2.0% (CI 1.6-2.3) reported using prescription medication at least three times a week in the past 30 days to stay awake.

In Coparison to the Active Service Members

RAND researchers developed regression models to compare HRBS results for active and reserve soldiers, taking into account respondents' demographic characteristics. Significant differences between reservists and active duty service members included the following

• greater overweight
• lower physical activity levels
• higher level of strength training
• less screen time
• longer and better quality sleep
• use fewer energy drinks to stay awake

Conclusions and Implications for Politics

The reserve component is close to the HP2020 targets for normal weight. One reason may be the prevalence of physical activity among members: most reservists exceed the HP2020 targets for physical activity and strength training.

Reservists also report the active component to be frequent weight loss and improved sleep. However, reservists were less likely than active members to meet HP2020 targets for body weight and physical activity. This may be problematic if these reservists are called to active duty.

Perhaps even more worrying is the proportion of reservists who did not report having an annual medical check-up in the past year and who reported not having health insurance. A recent medical examination is required when going on deployment, and the lack of insurance may lead reservists to postpone the examination.

The Department of Defense, the services and the Coast Guard should work to improve reservists' compliance with medical examinations. They may also wish to appoint a health advisor to help reserve units obtain low-cost health insurance premiums and increase the number of members insured in the public or private market.

Methodology

RAND conducted the 2018 HRBS survey of active duty and reserve military personnel in the U.S. from October 2018 to March 2019. The Reserve Components survey included five Reserve Components – Air Force, Army, Navy, Marine Corps, and Coast Guard – and two National Guard force types – the 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. The sample was selected using a random sampling method stratified 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 address missing data, RAND researchers used imputation, a statistical procedure that uses available data to estimate missing values. To represent reservists, responses were weighted to account for the oversampling of military personnel in certain sections. Point estimates and 95% CIs are presented in this research report.

RAND researchers tested whether there were differences in each outcome at key factor levels or subgroups – branch of service, grade, gender, race/ethnicity, and age group – using a two-step procedure, based on the Rao-Scott chi-square test for overall differences in individual factor levels and, if the overall test was statistically significant, a two-sample t-test for all possible pairwise comparisons between factor levels (e.g. men and women).

Readers interested in these differences should consult the full final report of the HRBS 2018 reserve component. This memo is one of eight memos on the Reserve; this memo and six of the seven other memos are drawn from various chapters throughout the report, with chapter eight providing an overview of all findings and policy implications. A similar series of eight reports deals with the results of the active part.

Restrictions

The response rate to the survey is considered low. 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.