Military Health System

Offspring Sex Ratio of Male Active Duty U.S. Navy Submariners, 2001–2015

The natural human sex ratio at birth (male:female) slightly favors males, and altered sex ratios might be indicative of exposure to reproductive hazards.

Surveillance Snapshot: Human Papillomavirus Vaccination Among U.S. Active Component Service Members in the Millennium Cohort Study, 2006–2017

The U.S. Millennium Cohort Study is a population-based prospective study that includes over 200,000 current and prior U.S. military service members.

Female Infertility, Active Component Service Women, U.S. Armed Forces, 2013–2018

As in prior years, mental health disorders, pregnancy-related conditions, and injury/poisoning accounted for the majority (59.8%) of all hospitalizations among active component service members in 2018. However, the hospitalization rate for all causes was the lowest rate in the past 10 years.

Ambulatory visits, active component, U.S. Armed Forces, 2018

Musculoskeletal disorders and mental health disorders accounted for more than half (52.6%) of all illness- and injury-related ambulatory encounters among active component service members in 2018. Since 2014, the number of ambulatory visits for mental health disorders has decreased, while the numbers of ambulatory visits for musculoskeletal system/connective tissue disorders, nervous system and sense organ disorders, and respiratory system disorders have increased.

Surveillance Snapshot: Illness and Injury Burdens, Recruit Trainees, Active Component, U.S. Armed Forces, 2018

Medical evacuations out of the U.S. Central Command, active and reserve components, U.S. Armed Forces, 2018

The number of medical evacuations for battle injuries has decreased considerably since 2014. Most medical evacuations in 2018 were attributed to mental health disorders, followed by non-battle injury/poisoning; signs, symptoms, and ill-defined conditions; musculoskeletal disorders; and digestive system disorders.

Hospitalizations, active component, U.S. Armed Forces, 2018

As in prior years, mental health disorders, pregnancy-related conditions, and injury/poisoning accounted for the majority (59.8%) of all hospitalizations among active component service members in 2018. However, the hospitalization rate for all causes was the lowest rate in the past 10 years.

Surveillance Snapshot: Illness and Injury Burdens, Reserve Component, U.S. Armed Forces, 2018

Morbidity burdens attributable to various illnesses and injuries, deployed active and reserve component service members, U.S. Armed Forces, 2018

Among service members deployed during 2018, injury/poisoning, musculoskeletal diseases, and signs/symptoms accounted for more than half of the total health care burden while deployed. Compared to the distribution of major burden of disease categories documented in garrison, a relatively greater proportion of in-theater medical encounters due to respiratory infections, skin diseases, infectious/parasitic diseases, and digestive diseases was documented.

Absolute and relative morbidity burdens attributable to various illnesses and injuries, non-service member beneficiaries of the Military Health System, 2018

In 2018, mental health disorders accounted for the largest proportions of the morbidity and healthcare burdens that affected the pediatric and younger adult beneficiary age groups. Among adults aged 45–64 years, musculoskeletal diseases accounted for the most morbidity and health care burdens, and among adults aged 65 years or older, cardiovascular diseases accounted for the most.

Absolute and relative morbidity burdens attributable to various illnesses and injuries, active component, U.S. Armed Forces, 2018

In 2018, mental health disorders accounted for the largest proportions of the morbidity and healthcare burdens that affected the pediatric and younger adult beneficiary age groups. Among adults aged 45–64 years, musculoskeletal diseases accounted for the most morbidity and healthcare burdens, and among adults aged 65 years or older, cardiovascular diseases accounted for the most.

Update: Exertional Rhabdomyolysis, Active Component, U.S. Armed Forces, 2014–2018

Among active component service members in 2018, there were 545 incident diagnoses of rhabdomyolysis likely due to exertional rhabdomyolysis, for an unadjusted incidence rate of 42.0 cases per 100,000 person-years. Subgroup-specific rates in 2018 were highest among males, those less than 20 years old, Asian/Pacific Islander service members, Marine Corps and Army members, and those in combat-specific or “other/unknown” occupations. During 2014–2018, crude rates of exertional rhabdomyolysis increased steadily from 2014 through 2016 after which rates declined slightly in 2017 before increasing again in 2018. Compared to service members in other race/ethnicity groups, the overall rate of exertional rhabdomyolysis was highest among non-Hispanic blacks in every year except 2018. Overall and annual rates were highest among Marine Corps members, intermediate among those in the Army, and lowest among those in the Air Force and Navy. Most cases of exertional rhabdomyolysis were diagnosed at installations that support basic combat/recruit training or major ground combat units of the Army or the Marine Corps. Medical care providers should consider exertional rhabdomyolysis in the differential diagnosis when service members (particularly recruits) present with muscular pain or swelling, limited range of motion, or the excretion of dark urine (possibly due to myoglobinuria) after strenuous physical activity, particularly in hot, humid weather.

Update: Heat Illness, Active Component, U.S. Armed Forces, 2018

In 2018, there were 578 incident diagnoses of heat stroke and 2,214 incident diagnoses of heat exhaustion among active component service members. The overall crude incidence rates of heat stroke and heat exhaustion diagnoses were 0.45 cases and 1.71 cases per 1,000 person-years, respectively. In 2018, subgroup-specific rates of incident heat stroke diagnoses were highest among males and service members less than 20 years old, Asian/Pacific Islanders, Marine Corps and Army members, recruit trainees, and those in combat-specific occupations. Subgroup-specific incidence rates of heat exhaustion diagnoses in 2018 were notably higher among service members less than 20 years old, Asian/Pacific Islanders, Army and Marine Corps members, recruit trainees, and service members in combat-specific occupations. During 2014–2018, a total of 325 heat illnesses were documented among service members in Iraq and Afghanistan; 8.6% (n=28) were diagnosed as heat stroke. Commanders, small unit leaders, training cadre, and supporting medical personnel must ensure that the military members whom they supervise and support are informed about the risks, preventive countermeasures, early signs and symptoms, and first-responder actions related to heat illnesses.

Incidence, Timing, and Seasonal Patterns of Heat Illnesses During U.S. Army Basic Combat Training, 2014–2018

Risk factors for heat illnesses (HIs) among new soldiers include exercise intensity, environmental conditions at the time of exercise, a high body mass index, and conducting initial entry training during hot and humid weather when recruits are not yet acclimated to physical exertion in heat. This study used data from the Defense Health Agency’s–Weather-Related Injury Repository to calculate rates and to describe the incidence, timing, and geographic distribution of HIs among soldiers during U.S. Army basic combat training (BCT). From 2014 through 2018, HI events occurred in 1,210 trainees during BCT, resulting in an overall rate of 3.6 per 10,000 BCT person-weeks (p-wks) (95% CI: 3.4–3.8). HI rates (cases per 10,000 BCT p-wks) varied among the 4 Army BCT sites: Fort Benning, GA (6.8); Fort Jackson, SC (4.4); Fort Sill, OK (1.8); and Fort Leonard Wood, MO (1.7). Although the highest rates ofHIs occurred at Fort Benning, recruits in all geographic areas were at risk. The highest rates of HI occurred during the peak training months of June through Sept., and over half of all HI cases affected soldiers during the first 3 weeks of BCT. Prevention of HI among BCT soldiers requires relevant training of both recruits and cadre as well as the implementation of effective preventive measures.

Update: Exertional Hyponatremia, Active Component, U.S. Armed Forces, 2003–2018

From 2003 through 2018, there were 1,579 incident diagnoses of exertional hyponatremia among active component service members, for a crude overall incidence rate of 7.2 cases per 100,000 person-years (p-yrs). Compared to their respective counterparts, females, those less than 20 years old, and recruit trainees had higher overall incidence rates of exertional hyponatremia diagnoses. The overall incidence rate during the 16-year period was highest in the Marine Corps, intermediate in the Army and Air Force, and lowest in the Navy. Overall rates during the surveillance period were highest among Asian/Pacific Islander and non-Hispanic white service members and lowest among non-Hispanic black service members. Between 2003 and 2018, crude annual incidence rates of exertional hyponatremia peaked in 2010 (12.7 per 100,000 p-yrs) and then decreased to 5.3 cases per 100,000 p-yrs in 2013 before increasing in 2014 and 2015. The crude annual rate in 2018 (6.3 per 100,000 p-yrs) represented a decrease of 26.5% from 2015. Service members and their supervisors must be knowledgeable of the dangers of excessive water consumption and the prescribed limits for water intake during prolonged physical activity (e.g., field training exercises, personal fitness training, and recreational activities) in hot, humid weather.