Skip to main content

Military Health System

Test of Sitewide Banner

This is a test of the sitewide banner capability. In the case of an emergency, site visitors would be able to visit the news page for addition information.

Morbidity Burdens Attributable to Various Illnesses and Injuries, Deployed Active and Reserve Component Service Members, U.S. Armed Forces, 2021

Image of 5_deployed morbidity. Marines shield themselves from a detonated explosive charge during a breaching exercise. Modern body armor better protects warfighters against shrapnel from explosive blasts. However, they still face the resulting blast pressure and shock wave that could cause traumatic brain injury. (U.S. Marine Corps photo by Sgt. Emmanuel Ramos)

What are the new findings?

As in previous years, among service members deployed during 2021, injury/poisoning, musculoskeletal diseases and signs/symptoms accounted for more than half of the total health care burden during deployment. Compared to garrison disease burden, deployed service members had relatively higher proportions of encounters for respiratory infections, skin diseases, and infectious and parasitic diseases. The recent marked increase in the percentage of total medical encounters attributable to the ICD diagnostic category "other" (23.0% in 2017 to 44.4% in 2021) is likely due to increases in diagnostic testing and immunization associated with the response to the COVID-19 pandemic.

What is the impact on readiness and force health protection?

Injuries and musculoskeletal diseases account for the greatest burden of deployed medical care and continued focus on surveillance and preventive measures for these health threats is warranted. While deployed, readiness may be impacted by conditions associated with austere environmental and sanitary conditions.

Every year, the MSMR estimates illness-and injury-related morbidity and health care burdens on the U.S. Armed Forces and the Military Health System (MHS) using electronic records of medical encounters from the Defense Medical Surveillance System (DMSS). These records document health care delivered in the fixed medical facilities of the MHS and in civilian medical facilities when care is paid for by the MHS. Health care encounters of deployed service members are documented in records that are maintained in the Theater Medical Data Store (TMDS), which is incorporated into the DMSS. This report updates previous analyses examining the distributions of illnesses and injuries that accounted for medical encounters (“morbidity burdens”) of active component members in deployed settings in the U.S. Central Command (USCENTCOM) and the U.S. Africa Command (USAFRICOM) areas of operations during the 2021 calendar year.1


The surveillance population included all individuals who served in the active or reserve components of the U.S. Army, Navy, Air Force, or Marine Corps and who had records of health care encounters captured in the TMDS during the surveillance period. The analysis was restricted to encounters where the theater of care specified was USCENTCOM or USAFRICOM or where the name of the theater of operation was missing or null; by default, this excluded encounters in the U.S. Northern Command, U.S. European Command, U.S. Indo-Pacific Command, or U.S. Southern Command theaters of operations. In addition, TMDS-recorded medical encounters where the data source was identified as Shipboard Automated Medical System (e.g., SAMS, SAMS8, SAMS9) or where the military treatment facility descriptor indicated that care was provided aboard a ship (e.g., USS George H.W. Bush or USS Dwight D. Eisenhower) were excluded from this analysis. Encounters from aeromedical staging facilities outside of USCENTCOM or USAFRICOM (e.g., the 779th Medical Group Aeromedical Staging Facility or the 86th Contingency Aeromedical Staging Facility) were also excluded. Inpatient and outpatient medical encounters were summarized according to the primary (first-listed) diagnoses (if reported with an International Classification of Diseases, 10th Revision [ICD-10] code between A00 and U09 or beginning with Z37). Primary diagnoses that did not correspond to an ICD-9 or ICD-10 code (e.g., 1XXXX, 4XXXX) were not reported in this burden analysis.

In tandem with the methodology described on pages 2–3 of this issue of the MSMR, all illness- and injury-specific diagnoses were grouped into 153 burden of disease-related conditions and 25 major categories based on a modified version of the classification system developed for the Global Burden of Disease (GBD) study.2 The morbidity burdens attributable to various conditions were estimated on the basis of the total number of medical encounters attributable to each condition (i.e., total hospitalizations and ambulatory visits for the condition with a limit of 1 encounter per individual per condition per day) and the numbers of service members affected by the conditions. In general, the GBD system groups diagnoses with common pathophysiologic or etiologic bases and/or significant international health policymaking importance. For this analysis, some diagnoses that are grouped into single categories in the GBD system (e.g., mental health disorders) were disaggregated. Also, injuries were categorized by the affected anatomic sites rather than by causes because external causes of injuries are not completely reported in TMDS records. It is important to note that because the TMDS has not fully transitioned to ICD-10 codes, some ICD-9 codes appear in this analysis. In addition to the examination of the distribution of diagnoses by the 153 conditions and the 25 major categories of disease burden, a third analysis depicts the distribution of diagnoses according to the 17 traditional categories of the ICD system, plus an 18th category dedicated to COVID-19.


In 2021, a total of 131,694 medical encounters occurred among 48,457 individuals while deployed to Southwest Asia/Middle East and Africa. Of the total medical encounters, 141 (0.11%) were indicated to be hospitalizations (data not shown). A majority of the medical encounters (75.7%), individuals affected (79.9%), and hospitalizations (79.4%) occurred among male service members (Figures 1a, 1b).

Medical encounters/individuals affected by burden of disease categories

During 2021, the percentages of total medical encounters by burden of disease categories in both deployed male and female service members were generally similar; in both sexes, more encounters were attributable to injury/poisoning, musculoskeletal diseases, and signs/symptoms (including ill-defined conditions) than any other categories (Figures 1a, 1b, 2a, 2b). The substantial burden of these disease categories on total medical encounters was also reflected as the top-3 categories for which individuals received medical care while deployed. Of note, female service members had a greater proportion of medical encounters for genitourinary diseases (5.8%) compared to male service members (1.1%).

Among both male and female service members, 4 burden conditions (other back problems, arm/shoulder injuries, knee injuries, and all other signs and symptoms) were among the top 5 burden conditions that accounted for the most medical encounters in 2021 (Figures 3a, 3b). The remaining burden conditions among the top 5 were organic sleep disorders (specifically, circadian rhythm disorders) among male service members and foot and ankle injuries among female service members.

The 4-digit ICD-10 code with the most medical encounters in the other back problems category during 2021 was for low back pain (data not shown). For all other musculoskeletal diseases, the most common 4-digit ICD code for both male and female service members was for cervicalgia. The most common 4-digit ICD-10 codes for arm/shoulder injuries and knee injuries were for pain in the specified body part (e.g., pain in right or left shoulder or pain in right or left knee) (data not shown). The 4-digit ICD-10 code with the third most medical encounters was for acute upper respiratory infection, unspecified (data not shown).

Of note, among male service members, less than 0.3% of all medical encounters during deployment were associated with any of the following major morbidity categories: metabolic/immunity disorders, other neoplasms, endocrine disorders, congenital anomalies, malignant neoplasms, diabetes mellitus, blood disorders, and nutritional disorders (Figure 1a). Among female service members, less than 0.3% of all medical encounters during deployment were associated with maternal conditions, nutritional disorders, blood disorders, congenital anomalies, metabolic/immunity disorders, malignant neoplasms, diabetes mellitus, and perinatal conditions (Figure 1b).

Medical encounters by major ICD-10 diagnostic category

In 2021, among the 18 major ICD-10 diagnostic categories, the largest percentages of medical encounters were attributable to “other” (includes factors influencing health status and contact with health services as well as external causes of morbidity), followed by musculoskeletal system/connective tissue (Figure 4). The percentage of total medical encounters attributable to “other” increased from 23% in 2017 to 44% in 2021. The top 3 most common ICD-10 diagnoses in the “other” category in 2021 included Z11.59 (28%, Encounter for screening for other viral diseases), Z02.89 (19%, Encounter for other administrative examinations), and Z23 (16%, Inoculations and vaccinations). Encounters for COVID-19 accounted for 0.4% of the total medical encounters in 2021 (data not shown). The percentage of medical encounters attributable to injury and poisoning decreased from 9.8% in 2017 to 5.0% in 2021 (Figure 4). The percentages of medical encounters attributable to the remaining major ICD diagnostic categories were relatively similar during the years 2017, 2019, and 2021.

Editorial Comment 

This report documents the morbidity and health care burden among U.S. military members while deployed to Southwest Asia/Middle East and Africa during 2021. Similar to results from earlier surveillance periods,1,3,4 3 burden categories—injury/poisoning, musculoskeletal diseases, and signs/symptoms—together accounted for more than one-half of the total health care burden in theater among both male and female deployers. The 2021 percentages of encounters due to “other” health encounters may have been driven by increased screening and vaccination for COVID-19, although this was not investigated in detail in this report.

Compared to the distribution of major burden of disease categories documented in garrison, this report also demonstrates relatively greater proportions of in-theater medical encounters due to respiratory infections, skin diseases, and infectious and parasitic diseases. The lack of certain amenities and greater exposure to austere environmental conditions may have compromised hygienic practices and contributed to this finding. In contrast, compared to the distribution of burden of disease in garrison, a relatively lower proportion of in-theater medical encounters due to mental health disorders was observed.5 This finding may be due to a number of factors including pre-deployment screening and the continued emphasis on promoting psychological health and resilience in deployed service members.

However, 4 of the top 5 major burden of disease categories in-theater—injury/poisoning, musculoskeletal diseases, signs/symptoms, and mental health disorders—were the same as those reported in non-deployed settings.5 Injury/poisoning ranked first in both settings and musculoskeletal diseases ranked second in-theater and third in non-deployed settings.5 The similarity in these top conditions is likely attributable to the fact that both deployed and non-deployed populations generally comprise young and healthy individuals undergoing strenuous physical and mental tasks.

Encounters for certain conditions are not expected to occur often in deployment settings. For example, the presence of some conditions (e.g., diabetes, pregnancy, or congenital anomalies) makes the affected service members ineligible for deployment. As a result of this selection process, deployed service members are generally healthier than their non-deployed counterparts and, specifically, less likely to require medical care for conditions that preclude deployment. The overall result of such predeployment medical screening is diminished health care burdens (as documented in the TMDS) related to certain disease categories.

Interpretation of the data in this report should be done with consideration of some limitations. Not all medical encounters in theaters of operation are captured in the TMDS. Some care is rendered by medical personnel at small, remote, or austere forward locations where electronic documentation of diagnoses and treatment is not feasible. As a result, the data described in this report likely underestimate the total burden of health care actually provided in the areas of operation examined. In particular, some emergency medical care provided to stabilize combat-injured service members before evacuation may not be routinely captured in the TMDS. Another limitation derives from the potential for misclassification of diagnoses due to errors in the coding of diagnoses entered into the electronic health record. Although the aggregated distributions of illnesses and injuries found in this study are compatible with expectations derived from other examinations of morbidity in military populations (both deployed and non-deployed), instances of incorrect diagnostic codes (e.g., coding a spinal cord injury using a code that denotes the injury was suffered as a birth trauma rather than using a code indicating injury in an adult) warrant caution in the interpretation of some findings. Although such coding errors are not common, their presence serves as a reminder of the extent to which this study depends on the capture of accurate information in the sometimes austere deployment environment in which health care encounters occur.


  1. Armed Forces Health Surveillance Division. Morbidity burdens attributable to various illnesses and injuries, deployed active and reserve component service members, U.S. Armed Forces, 2020. MSMR. 2021; 28(6): 34–39.
  2. Murray CJ and Lopez AD, eds. In: Global Burden of Disease: A Comprehensive Assessment of Mortality and Disability from Diseases, Injuries, and Risk Factors in 1990 and Projected to 2020. Cambridge, MA: Harvard University Press; 1996:120–122.
  3. Armed Forces Health Surveillance Branch. Morbidity burdens attributable to various illnesses and injuries in deployed (per Theater Medical Data Store [TMDS]) active and reserve component service members, U.S. Armed Forces, 2008–2014. MSMR. 2015;22(8):17–22.
  4. Armed Forces Health Surveillance Branch. Morbidity burdens attributable to various illnesses and injuries, deployed active and reserve component service members, 2019. MSMR. 2015;27(5):33–38.
  5. Armed Forces Health Surveillance Branch. Absolute and relative morbidity burdens attributable to various illnesses and injuries, active component, U.S. Armed Forces, 2021. MSMR. 2022;29(6):2–X.

FIGURE 1a. Medical encountersa and individuals affected,b by burden of disease major category,c deployed male service members, U.S. Armed Forces, 2021

FIGURE 1b. Medical encountersa and individuals affected,b by burden of disease major category,c deployed female service members, U.S. Armed Forces, 2021

FIGURE 2a. Percentage of medical encounters,a by burden of disease major category,b deployed male service members, U.S. Armed Forces, 2021

FIGURE 2b. Percentage of medical encounters,a by burden of disease major category,b deployed female service members, U.S. Armed Forces, 2021

FIGURE 3a. Percentage and cumulative percentage distribution, burden of disease-related conditionsa that accounted for the most medical encounters, deployed male service members, U.S. Armed Forces, 2021

FIGURE 3b. Percentage and cumulative percentage distribution, burden of disease-related conditionsa that accounted for the most medical encounters, deployed female service members, U.S. Armed Forces, 2021

FIGURE 4. ICD-9/ICD-10 diagnostic categories of in-theater medical encounters, active component, U.S. Armed Forces, 2017, 2019, and 2021

You also may be interested in...

Sep 1, 2022

Update: Routine Screening for Antibodies to Human Immunodeficiency Virus, U.S. Armed Forces, Active and Reserve Components, January 2017–June 2022

NAVAL MEDICAL CENTER CAMP LEJEUNE, North Carolina - As the leading petty officer for Naval Medical Center Camp Lejeune's Community Health Clinic, HM2 Kameron Jacobs is part of the first satellite team to treat service members living with HIV.

This report provides an update through June 2022 of routine screening results for antibodies to the human immunodeficiency virus (HIV) among members of the active and reserve components of the U.S. Armed Forces. During the full 5 and 1/2-year surveillance period, the HIV seropositivity rates for active component service members were 0.21 positives per ...

Sep 1, 2022

Evaluation of the MSMR Surveillance Case Definition for Incident Cases of Hepatitis C

U.S. Marine Corps Lance Cpl. Angel Alvarado, a combat graphics specialist, donates blood for the Armed Services Blood Program (ASBP).

The validity of military hepatitis C virus (HCV) surveillance data is uncertain due to the potential for misclassification introduced when using administrative databases for surveillance purposes. The objectives of this study were to assess the validity of the surveillance case definition used by the Medical Surveillance Monthly Report (MSMR) for HCV ...

Sep 1, 2022

Brief Report: Menstrual Suppression Among U.S. Female Service Members in the Millennium Cohort Study

U.S. Marine Corps Lance Cpl. Bobby Brodeur, a Gilford, New Hampshire, native and machine gunner with 3rd Battalion, 6th Marine Regiment, 2d Marine Division, conducts gun drills at Camp Lejeune, North Carolina, Oct. 13, 2022. Brodeur is currently serving as a machine gunner with 3/6 and is one of three female infantry Marines in Kilo Co. She has demonstrated an unwavering commitment to 3/6 through her high physical fitness scores and leading by example within the platoon. (U.S. Marine Corps photo by Lance Cpl. Megan Ozaki)

Menstrual suppression allows for the control or complete suppression of menstrual periods through hormonal contraceptive methods. In addition to preventing pregnancy, suppression can alleviate medical conditions and symptoms associated with menstruation such as iron deficiency anemia,1 eliminate logistical hygiene-related challenges, and improve ...

Aug 1, 2022

Brief Report: Pain and Post-Traumatic Stress Disorder Screening Outcomes Among Military Personnel Injured During Combat Deployment.

U.S. Air Force Airman 1st Class Miranda Lugo, right, 18th Operational Medical Readiness Squadron mental health technician and Guardian Wingman trainer, and Maj. Joanna Ho, left, 18th OMRS director of psychological health, discuss the suicide prevention training program, Guardian Wingman, at Kadena Air Base, Japan, Aug. 20, 2021. Guardian Wingman aims to promote wingman culture and early help-seeking behavior. (U.S. Air Force photo by Airman 1st Class Anna Nolte)

The post-9/11 U.S. military conflicts in Iraq and Afghanistan lasted over a decade and yielded the most combat casualties since the Vietnam War. While patient survivability increased to the high­est level in history, a changing epidemiology of combat injuries emerged whereby focus shifted to addressing an array of long-term sequelae, including ...

Aug 1, 2022

Musculoskeletal Injuries During U.S. Air Force Special Warfare Training Assessment and Selection, Fiscal Years 2019–2021.

U.S. Air Force Capt. Hopkins, 351st Special Warfare Training Squadron, Instructor Flight commander and Chief Combat Rescue Officer (CRO) instructor, conducts a military free fall equipment jump from a DHC-4 Caribou aircraft in Coolidge, Arizona, July 17, 2021. Hopkins is recognized as the 2020 USAF Special Warfare Instructor Company Grade Officer of the Year for his outstanding achievement from January 1 to December 31, 2020.

Musculoskeletal (MSK) injuries are costly and the leading cause of medical visits and disability in the U.S. military.1,2 Within training envi­ronments, MSK injuries may lead to a loss of training, deferment to a future class, or voluntary disenrollment from a training pipeline, all of which are impediments to maintaining full levels of manpower and ...

Jul 1, 2022

Establishment of SARS-CoV-2 Genomic Surveillance Within the Military Health System During 1 March–31 December 2020.

Dr. Peter Larson loads an Oxford Nanopore MinION sequencer in support of COVID-19 sequencing assay development at the U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland. (Photo by John Braun Jr., USAMRIID.)

This report describes SARS-CoV-2 genomic surveillance conducted by the Department of Defense (DOD) Global Emerging Infections Surveillance Branch and the Next-Generation Sequencing and Bioinformatics Consortium (NGSBC) in response to the COVID-19 pandemic. Samples and sequence data were from SARS-CoV-2 infections occurring among Military Health System ...

Jul 1, 2022

Brief Report: Phase I Results Using the Virtual Pooled Registry Cancer Linkage System (VPR-CLS) for Military Cancer Surveillance.

A patient at Naval Hospital Pensacola prepares to have a low-dose computed tomography test done to screen for lung cancer. Lung cancer is the leading cause of cancer-related deaths among men and women. Early detection can lower the risk of dying from this disease. (U.S. Navy photo by Jason Bortz)

The Armed Forces Health Surveillance Division, as part of its surveillance mission, periodically conducts studies of cancer incidence among U.S. military service members. However, service members are likely lost to follow-up from the Department of Defense cancer registry and Military Health System data sets after leaving service and during periods of ...

Jul 1, 2022

Surveillance Trends for SARS-CoV-2 and Other Respiratory Pathogens Among U.S. Military Health System Beneficiaries, 27 September 2020–2 October 2021.

Staff Sgt. Misty Poitra and Senior Airman Chris Cornette, 119th Medical Group, collect throat swabs during voluntary COVID-19 rapid drive-thru testing for members of the community while North Dakota Army National Guard Soldiers gather test-subject data in the parking lot of the FargoDome in Fargo, N.D., May 3, 2020. The guardsmen partnered with the N.D. Department of Health and other civilian agencies in the mass-testing efforts of community volunteers. (U.S. Air National Guard photo by Chief Master Sgt. David H. Lipp)

Respiratory pathogens, such as influenza and adenovirus, have been the main focus of the Department of Defense Global Respiratory Pathogen Surveillance Program (DoDGRPSP) since 1976.1. However, DoDGRPSP also began focusing on SARS-CoV-2 when COVID-19 was declared a pandemic illness in early March 2020.2. Following this declaration, the DOD quickly ...

Jul 1, 2022

Suicide Behavior Among Heterosexual, Lesbian/Gay, and Bisexual Active Component Service Members in the U.S. Armed Forces.

  The DOD’s theme for National Suicide Prevention Month is “Connect to Protect: Support is Within Reach.” Deployments, COVID-19 restrictions, and the upcoming winter season are all stressors and potential causes for depression that could lead to suicidal ideations. Options are available to individuals who are having thoughts of suicide and those around them (Photo by Kirk Frady, Regional Health Command Europe).

Lesbian, gay, and bisexual (LGB) individuals are at a particularly high risk for suicidal behavior in the general population of the United States. This study aims to determine if there are differences in the frequency of lifetime suicide ideation and suicide attempts between heterosexual, lesbian/gay, and bisexual service members in the active ...

Jun 1, 2022

Absolute and Relative Morbidity Burdens Attributable to Various Illnesses and Injuries, Active Component, U.S. Armed Forces, 2021

In 2021, as in prior years, the medical conditions associated with the most medical encounters, the largest number of affected service members, and the greatest number of hospital days were in the major categories of injuries, musculoskeletal disorders, and mental health disorders. Despite the pandemic, COVID-19 accounted for less than 2% of total ...

Jun 1, 2022

Hospitalizations, Active Component, U.S. Armed Forces, 2021

The hospitalization rate in 2021 was 48.0 per 1,000 person-years (p-yrs), the second lowest rate of the most recent 10 years. For hospitalizations limited to military facilities, the rate in 2021 was the lowest for the entire period. As in prior years, the majority (71.2%) of hospitalizations were associated with diagnoses in the categories of mental ...

Refine your search
Last Updated: July 11, 2023
Follow us on Instagram Follow us on LinkedIn Follow us on Facebook Follow us on Twitter Follow us on YouTube Sign up on GovDelivery