Sudden death in young adults: an autopsy-based series of a population undergoing active surveillance.

OBJECTIVES: The purpose of this study was to define the incidence and characterization of cardiovascular cause of sudden death in the young. BACKGROUND: The epidemiology of sudden cardiac death (SCD) in young adults is based on small studies and uncontrolled observations. Identifying causes of sudden death in this population is important for guiding approaches to prevention. METHODS: We performed a retrospective cohort study using demographic and autopsy data from the Department of Defense Cardiovascular Death Registry over a 10-year period comprising 15.2 million person-years of active surveillance. RESULTS: We reviewed all nontraumatic sudden deaths in persons 18 years of age and over. We identified 902 subjects in whom the adjudicated cause of death was of potential cardiac etiology, with a mean age of 38 ± 11 years. The mortality rate for SCD per 100,000 person-years for the study period was 6.7 for males and 1.4 for females (p < 0.0001). Sudden death was attributed to a cardiac condition in 715 (79.3%) and was unexplained in 187 (20.7%). The incidence of sudden unexplained death (SUD) was 1.2 per 100,000 person-years for persons <35 years of age, and 2.0 per 100,000 person-years for those ≥ 35 years of age (p < 0.001). The incidence of fatal atherosclerotic coronary artery disease was 0.7 per 100,000 person-years for those <35 years of age, and 13.7 per 100,000 person-years for those ≥ 35 years of age (p < 0.001). CONCLUSIONS: Prevention of sudden death in the young adult should focus on evaluation for causes known to be associated with SUD (e.g., primary arrhythmia) among persons <35 years of age, with an emphasis on atherosclerotic coronary disease in those ≥ 35 years of age.

Incidence of primary blast injury in US military overseas contingency operations: a retrospective study.

OBJECTIVES: The present retrospective study was performed to determine the incidence and outcome of primary blast injury and to identify possible changes over the course of the conflicts between 2003 and 2006. SUMMARY BACKGROUND DATA: Combat physicians treating patients injured in overseas contingency operations observed an increase in the severity of explosion injuries occurring during this period. METHODS: This retrospective study included service members injured in explosions between March 2003 and October 2006. The Joint Theater Trauma Registry provided demographic information, injury severity score, and International Classification of Diseases 9 codes used to diagnose primary blast injury. Autopsy reports of the last 497 combat-related deaths of 2006 were also reviewed. RESULTS: Of 9693 admissions, of which 6687 were injured in combat, 4765 (49%) were injured by explosions: 2588 in 2003-2004 and 1935 in 2005-2006. Dates of injury were unavailable for 242 casualties. Injury severity score (9 +/- 10 vs. 11 +/- 10, P < 0.0001) and incidence of primary blast injury (12% vs. 15%, P < 0.01) increased. The return-to-duty rate decreased (40% vs. 18%, P < 0.001), but mortality remained low (1.4% vs. 1.5%, P = NS). There was no significant difference in incidence of primary blast injury between personnel who were killed in action and those who died of wounds at a medical facility. CONCLUSIONS: Injury severity and incidence of primary blast injury increased during the 4-year period, whereas return-to-duty rates decreased. Despite increasingly devastating injuries, the mortality rate due to explosion injuries remained low and unchanged.

Early mortality experience in a large military cohort and a comparison of mortality data sources.

BACKGROUND: Complete and accurate ascertainment of mortality is critically important in any longitudinal study. Tracking of mortality is particularly essential among US military members because of unique occupational exposures (e.g., worldwide deployments as well as combat experiences). Our study objectives were to describe the early mortality experience of Panel 1 of the Millennium Cohort, consisting of participants in a 21-year prospective study of US military service members, and to assess data sources used to ascertain mortality. METHODS: A population-based random sample (n = 256,400) of all US military service members on service rosters as of October 1, 2000, was selected for study recruitment. Among this original sample, 214,388 had valid mailing addresses, were not in the pilot study, and comprised the group referred to in this study as the invited sample. Panel 1 participants were enrolled from 2001 to 2003, represented all armed service branches, and included active-duty, Reserve, and National Guard members. Crude death rates, as well as age- and sex-adjusted overall and age-adjusted, category-specific death rates were calculated and compared for participants (n = 77,047) and non-participants (n = 137,341) based on data from the Social Security Administration Death Master File, Department of Veterans Affairs (VA) files, and the Department of Defense Medical Mortality Registry, 2001-2006. Numbers of deaths identified by these three data sources, as well as the National Death Index, were compared for 2001-2004. RESULTS: There were 341 deaths among the participants for a crude death rate of 80.7 per 100,000 person-years (95% confidence interval [CI]: 72.2,89.3) compared to 820 deaths and a crude death rate of 113.2 per 100,000 person-years (95% CI: 105.4, 120.9) for non-participants. Age-adjusted, category-specific death rates highlighted consistently higher rates among study non-participants. Although there were advantages and disadvantages for each data source, the VA mortality files identified the largest number of deaths (97%). CONCLUSIONS: The difference in crude and adjusted death rates between Panel 1 participants and non-participants may reflect healthier segments of the military having the opportunity and choosing to participate. In our study population, mortality information was best captured using multiple data sources.

Fatal airway injuries during Operation Enduring Freedom and Operation Iraqi Freedom.

INTRODUCTION: Airway compromise is the third leading cause of potentially preventable death on the battlefield. An understanding of the injuries associated with fatal airway compromise is necessary to develop improvements in equipment, training, and prehospital management strategies in order to maximize survival. OBJECTIVE: To determine injury patters resulting in airway compromise in the combat setting. METHODS: This was a subgroup analysis of cases previously examined by Kelly and colleagues, who reviewed autopsies of military personnel who died in combat in Iraq and Afghanistan between 2003 and 2006. Casualties with potentially survivable (PS) injuries and deaths related to airway compromise previously identified by Kelly et al. were reviewed in depth by a second panel of military physicians. RESULTS: There were 982 cases that met the inclusion criteria. Of these, 232 cases had PS injuries. Eighteen (1.8%) cases were found to have airway compromise as the likely cause of primary death. All had penetrating injuries to the face or neck. Twelve deaths (67%) were caused by gunshot wounds, while six deaths (33%) were caused by explosions. Nine cases had concomitant injury to major vascular structures, and eight had significant airway hemorrhage. Cricothyroidotomy was attempted in five cases; all were unsuccessful. CONCLUSION: Airway compromise from battlefield trauma results in a small number of PS fatalities. Penetrating trauma to the face or neck may be accompanied by significant hemorrhage, severe and multiple facial fractures, and airway disruption, leading to death from airway compromise. Cricothyroidotomy may be required to salvage these patients, but the procedure failed in all instances in this series of cases. Further studies are warranted to determine the appropriate algorithm of airway management in combat casualties sustaining traumatic airway injuries.

The use of electronic pharmacy data to investigate prescribed medications and fatal motor vehicle crashes in a military population, 2002-2006.

The authors examined the association between prescribed medications and fatal motor vehicle crashes (MVCs) in an active duty military population between 2002 and 2006. Using a case-control design, MVC deaths were ascertained using a military mortality registry, and an integrated health system database provided information on health system eligibility, pharmacy transactions, and medical encounters. Cases and controls were matched on comparable observation time outside periods of deployment. Among selected categories, only one, antidepressant medications, was an independent predictor of fatal MVC (odds ratio, 3.19; 95% confidence interval, 1.01-10.07). Male gender, Black race, enlisted rank, service branch (Navy and Marine Corps), and selected co-morbidities were also independent predictors. Unexpectedly, the odds of younger age quartiles (< 27 years) and history of deployment were reduced for MVC cases. Although results need to be considered in the context of data limitations, the association between prescribed antidepressants and fatal MVC may reflect unmeasured co-morbidities, such as combined effects of prescribed and over-the-counter medications and/or alcohol or other substance abuse. Younger individuals, representing new military accessions in training or returning from deployment with serious injuries, may have fewer opportunities to operate vehicles, or targeted efforts to reduce MVC following deployment may be showing a positive effect.

Injury severity and causes of death from Operation Iraqi Freedom and Operation Enduring Freedom: 2003-2004 versus 2006.

BACKGROUND: The opinion that injuries sustained in Iraq and Afghanistan have increased in severity is widely held by clinicians who have deployed multiple times. To continuously improve combat casualty care, the Department of Defense has enacted numerous evidence-based policies and clinical practice guidelines. We hypothesized that the severity of wounds has increased over time. Furthermore, we examined cause of death looking for opportunities of improvement for research and training. METHODS: Autopsies of the earliest combat deaths from Iraq and Afghanistan and the latest deaths of 2006 were analyzed to assess changes in injury severity and causes of death. Fatalities were classified as nonsurvivable (NS) or potentially survivable (PS). PS deaths were then reviewed in depth to analyze mechanism and cause. RESULTS: There were 486 cases from March 2003 to April 2004 (group 1) and 496 from June 2006 to December 2006 (group 2) that met inclusion criteria. Of the PS fatalities (group 1: 93 and group 2: 139), the injury severity score was lower in the first group (27 +/- 14 vs. 37 +/- 16, p < 0.001), and had a lower number of abbreviated injury scores >or=4 (1.1 +/- 0.79 vs. 1.5 +/- 0.83 per person, p < 0.001). The main cause of death in the PS fatalities was truncal hemorrhage (51% vs. 49%, p = NS). Deaths per month between groups doubled (35 vs. 71), whereas the case fatality rates between the two time periods were equivalent (11.0 vs. 9.8, p = NS). DISCUSSION: In the time periods of the war studied, deaths per month has doubled, with increases in both injury severity and number of wounds per casualty. Truncal hemorrhage is the leading cause of potentially survivable deaths. Arguably, the success of the medical improvements during this war has served to maintain the lowest case fatality rate on record.

Deaths attributed to suicide among enlisted U.S. Armed Forces recruits, 1980-2004.

OBJECTIVE: The purpose of this study was to describe the epidemiology of suicides among U.S. Air Force, Army, Marine Corps, and Navy recruits from 1980 through 2004. METHODS: Recruit suicides were identified through the Department of Defense Recruit Mortality Registry. We calculated crude, category-specific, and age-adjusted mortality rates as deaths per 100,000 recruit-years. RESULTS: There were 46 onsite suicides by gunshot (39%), hanging (35%), fall/jump (22%), and drug overdose (4%). An additional 20 recruits committed suicide from 1980 through 2004 after leaving the military training site. Methods included gunshot (70%), hanging (20%), fall/jump (5%), and poisoning (5%). Therefore, the overall recruit suicide rate was 6.9 (95% confidence interval = 5.4-8.8) deaths per 100,000 recruit-years. Only three (5%) suicides occurred among females resulting in a 3.5 times higher risk for males compared to females (95% confidence interval = 1.1-11.2). CONCLUSIONS: Suicide rates among military recruits were lower than those of comparably aged U.S. civilians. However, the occurrence of any suicide during basic military training emphasizes the importance of routine evaluation of the effectiveness of each military service's suicide prevention program as it applies to this population.

Drowning deaths of U.S. Service personnel associated with motor vehicle accidents occurring in Operation Iraqi Freedom and Operation Enduring Freedom, 2003-2005.

OBJECTIVE: We examined common factors in vehicular drowning deaths that might lead to changes in equipment or training. METHODS: Drowning deaths among service members deployed to Operations Iraqi Freedom or Enduring Freedom, 2003 to 2005, were ascertained using the Armed Forces Medical Examiner Tracking System database. Cases were linked to Army and Navy safety and investigative files. RESULTS: Fifty-two cases of vehicular drowning deaths were identified. These occurred mostly at night, were almost always the result of a rollover, and were most frequently associated with a high-mobility medium-weight vehicle. Seat belts were rarely worn, but the majority of injuries should not have been severe enough to affect egress from the vehicle. These drowning deaths seldom occurred while engaged with the enemy and were rarely associated with bad road conditions or bad weather. CONCLUSIONS: Effective preventive strategies might focus on training and equipment to reduce rollover events and on the expeditious extrication of victims.

Virtual autopsy: two- and three-dimensional multidetector CT findings in drowning with autopsy comparison.

PURPOSE: To retrospectively determine the multidetector computed tomographic (CT) virtual autopsy findings of death by drowning in comparison with autopsy findings. MATERIALS AND METHODS: The institutional review board of the Armed Forces Institute of Pathology approved this HIPAA-compliant study and did not require informed consent by the next of kin. Total-body multidetector CT was performed, immediately prior to routine autopsy, in 28 consecutive male subjects (mean age, 24.2 years) who died of drowning and a control group of 12 consecutive male subjects (mean age, 50.8 years) who died of sudden death from atherosclerotic coronary artery disease. Images were evaluated for the presence of fluid and sediment in the paranasal sinuses and airways, mastoid air cell fluid, frothy fluid in the airways, pulmonary opacity (ground-glass opacity or airspace consolidation), interlobular septal thickening, and gastric distention and contents (fluid or sediment). Image findings were compared with findings from autopsy reports and photographs. RESULTS: All drowning subjects had fluid in the paranasal sinuses and mastoid air cells and had ground-glass opacity within the lungs. Twenty-six subjects (93%) had fluid in the subglottic trachea and main bronchi. Fourteen subjects (50%) had high-attenuation sediment in the subglottic airways. Frothy fluid in the airways was present in six subjects (21%). Twenty-five (89%) of the drowning subjects had pulmonary ground-glass opacity with septal lines, which was mild with apical and perihilar distribution in 12 subjects, severe and diffuse in nine, posterior and basilar in three, and limited to the apices in one (not assessed in three of 28 subjects because of decomposition). Control subjects showed mastoid cell fluid (25%), sinus fluid (83%), subglottic airway fluid (92%), and pulmonary ground-glass opacity (100%) but did not have evidence of frothy airway fluid or high-attenuation sediment in the airways. CONCLUSION: The multidetector CT finding of frothy airway fluid or high-attenuation airway sediment is highly suggestive of drowning; multidetector CT findings of pan sinus fluid, mastoid cell fluid, subglottic tracheal and bronchial fluid, and ground-glass opacity within the lung at multidetector CT are supportive of drowning in the appropriate scenario.

Causes of death in U.S. Special Operations Forces in the global war on terrorism: 2001-2004.

BACKGROUND: Effective combat trauma management strategies depend upon an understanding of the epidemiology of death on the battlefield. METHODS: A panel of military medical experts reviewed photographs and autopsy and treatment records for all Special Operations Forces (SOF) who died between October 2001 and November 2004 (n = 82). Fatal wounds were classified as nonsurvivable or potentially survivable. Training and equipment available at the time of injury were taken into consideration. A structured analysis was conducted to identify equipment, training, or research requirements for improved future outcomes. RESULTS: Five (6%) of 82 casualties had died in an aircraft crash, and their bodies were lost at sea; autopsies had been performed on all other 77 soldiers. Nineteen deaths, including the deaths at sea were noncombat; all others were combat related. Deaths were caused by explosions (43%), gunshot wounds (28%), aircraft accidents (23%), and blunt trauma (6%). Seventy of 82 deaths (85%) were classified as nonsurvivable; 12 deaths (15%) were classified as potentially survivable. Of those with potentially survivable injuries, 16 causes of death were identified: 8 (50%) truncal hemorrhage, 3 (19%) compressible hemorrhage, 2 (13%) hemorrhage amenable to tourniquet, and 1 (6%) each from tension pneumothorax, airway obstruction, and sepsis. The population with nonsurvivable injuries was more severely injured than the population with potentially survivable injuries. Structured analysis identified improved methods of truncal hemorrhage control as a principal research requirement. CONCLUSIONS: The majority of deaths on the modern battlefield are nonsurvivable. Improved methods of intravenous or intracavitary, noncompressible hemostasis combined with rapid evacuation to surgery may increase survival.

Autopsy radiography: digital radiographs (DR) vs multidetector computed tomography (MDCT) in high-velocity gunshot-wound victims.

This study compared full-body digital radiography (DR) with multidetector computed tomography (MDCT) in the postmortem evaluation of gunshot wound (GSW) victims. Thirteen consecutive male GSW victims (mean age, 27 years) had full-body DR and MDCT prior to routine autopsy. DR successfully identified all metallic fragments, but MDCT was superior in its ability to precisely determine location because it provided 3-dimensional anatomic localization. In all cases, MDCT more accurately assessed organ injuries and wound tracks. Both DR and MDCT are limited in classifying multiple wounds and major vessel injury, but MDCT is generally superior to DR. MDCT shows significant advantages over DR in the forensic evaluation of GSW victims. This is particularly advantageous for the pathologist retrieving metallic fragments and for describing fracture detail accurately. Use of MDCT instead of radiographs will require medical examiners to become familiar with reading cross-sectional images.

Causes of death in US Special Operations Forces in the global war on terrorism: 2001-2004.

INTRODUCTION: Effective combat trauma management strategies depend on an understanding of the epidemiology of death on the battlefield, resulting in evidence-based equipment, training, and research requirements. METHODS: All Special Operations Forces (SOF) fatalities (combat and noncombat) in Operation Iraqi Freedom/Operation Enduring Freedom (OEF/OIF) from October 2001 until November 2004 were reviewed. All available autopsy and treatment records and photographs were used. In most cases, the immediate tactical situation was unknown. The review was performed by a multidisciplinary group including forensic pathologists, an SOF combat medic, and trauma surgeons. Fatalities were classified as having wounds that were either nonsurvivable or potentially survivable with existing training, equipment, and expertise on the battlefield. A structured review was performed evaluating the need for new equipment, training, or research requirements. Results were compared to autopsy data from Vietnam and modern civilian trauma center data. The study was approved by the Institutional Review Boards of the Armed Forces Institute of Pathology and the US Army Institute of Surgical Research. RESULTS: During the study period, 82 SOF fatalities were identified. Autopsies were performed on 77 Soldiers. Five casualties died secondary to aircraft crash, their bodies were not recovered from the ocean. For the purposes of this study they were considered nonsurvivable. Eighty-five percent (n = 70) of the fatalities sustained wounds that were nonsurvivable, while the remaining 15% (n = 12) had wounds that were potentially survivable. Injury Severity Score (ISS) was higher in the nonsurvivable group (p < 0.05). Truncal hemorrhage accounted for 47% of deaths while extremity hemorrhage accounted for 33%. One casualty was noted at autopsy to have a tension pneumothorax as well as multiple sources of internal hemorrhage, one suffered an airway death, while another died of sepsis 56 days after injury. Of those casualties deemed to be nonsurvivable, there were 31 patients with 40 Abbreviated Injury Score (AIS) 6 injuries (p = .0011), and 53 patients with 104 AIS 5 injuries. Among the 12 deaths deemed to be potentially survivable, there were only 8 AIS 5 injuries. Deaths were largely caused by explosions (n = 35), gunshot wounds (n = 23), and aircraft accidents (n = 19). No new training or equipment needs were identified for 53% of the potentially survivable deaths while improved methods of truncal hemorrhage control need to be developed for the remainder. The review panel concluded that 85% of the deaths would not have been prevented at a civilian Level I facility. Available records, in most cases, did not contain information about the use of body armor, time to death after injury, or the ongoing tactical situation. CONCLUSIONS: The majority of deaths on the modern battlefield are nonsurvivable. Current results are not different from previous conflicts. In Vietnam, reported potentially preventable death rates range from 5% to 35% and civilian data reports potentially preventable death rates ranging from 12% to 22%. Military munitions cause multiple lethal injuries. Current trauma training and equipment is sufficient to care for 53% of the potentially survivable deaths. Improved methods of intravenous or intracavitary noncompressible hemostasis combined with rapid surgery are required for the remaining 47% of the decedents.

Chest wall thickness in military personnel: implications for needle thoracentesis in tension pneumothorax.

Needle thoracentesis is an emergency procedure to relieve tension pneumothorax. Published recommendations suggest use of angiocatheters or needles in the 5-cm range for emergency treatment. Multidetector computed tomography scans from 100 virtual autopsy cases were used to determine chest wall thickness in deployed male military personnel. Measurement was made in the second right intercostal space at the midclavicular line. The mean horizontal thickness was 5.36 cm (SD = 1.19 cm) with angled (perpendicular) thickness slightly less with a mean of 4.86 cm (SD 1.10 cm). Thickness was generally greater than previously reported. An 8-cm angiocatheter would have reached the pleural space in 99% of subjects in this series. Recommended procedures for needle thoracentesis to relieve tension pneumothorax should be adapted to reflect use of an angiocatheter or needle of sufficient length.

Virtual autopsy: preliminary experience in high-velocity gunshot wound victims.

PURPOSE: To retrospectively assess virtual autopsy performed with multidetector computed tomography (CT) for the forensic evaluation of gunshot wound victims. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant study and did not require informed consent of the next of kin. Thirteen consecutive male gunshot wound victims (mean age, 27 years) were scanned with 16-section multidetector CT prior to routine autopsy. Retrospectively, the total-body nonenhanced scans were interpreted at a three-dimensional workstation by radiologists blinded to autopsy findings. Images were evaluated for lethal wound, number and location of wound tracks, injured structures, and metal fragment location. After image review, autopsy reports and photographs were compared with the images and interpretations to validate the multidetector CT determinations. RESULTS: Multidetector CT aided in correct identification of all lethal wounds, and metallic fragment location was always precise. In four cases, multidetector CT aided in accurate assessment of organ injuries and lethal wounds but led to underestimation of the number of wounds if comingling paths occurred. In two cases of a chest wound, multidetector CT aided in accurate assessment of the chest as having the lethal wound but failed to help identify specific sites of hemorrhage. In two cases of craniofacial injury, the path of the wound was not clear. Autopsy revealed a total of 78 wound tracks (mean, 6; range, 1-24). Ten (13%) wound tracks were not identified at multidetector CT (six upper extremity wounds and four thigh wounds). In two cases, findings missed at autopsy (fracture of the cervical spine, bullet fragments in the posterior area of the neck) were identified at multidetector CT. CONCLUSION: Multidetector CT can aid prediction of lethal wounds and location of metallic fragments.

Venous thromboembolism among United States soldiers deployed to Southwest Asia.

INTRODUCTION: Military operations may represent a high-risk environment for venous thromboembolism (VTE). We sought to identify and describe cases of venous thromboembolism among US military personnel serving in Southwest Asia, and estimate relative disease rates compared to non-deployed personnel. MATERIALS AND METHODS: Retrospective review of imaging archives, hospital discharge codes, case logs and autopsy records for the diagnosis of deep vein thrombosis or pulmonary embolism occurring from 1 March 2003 through 29 February 2004 among U.S. military personnel deployed to Southwest Asia. Rates of disease in deployed and non-deployed active-duty soldiers were estimated using personnel data and deployment experience obtained from automated rosters. RESULTS: Forty cases of venous thromboembolism were identified. The case-fatality rate was 16% (3/19) among those with pulmonary embolism. Antecedent trauma followed by prolonged air evacuation was present in 55% (22/40). Compared to trauma-associated cases, non-trauma cases were more commonly over 40 years old (44% vs. 5%; p<0.05), assigned to a transportation or quartermaster company (56% vs. 14%; p<0.05), or had a history of remote venous thromboembolism (31% vs. 0%; p<0.05). The overall incidence among deployed active-duty soldiers was 22.1/100,000 person-years. Compared to non-deployed active-duty soldiers, the age-adjusted incidence rate ratio was 1.06 (CI(0.95) 0.68-1.67). CONCLUSIONS: VTE rates among deployed soldiers are relatively low compared to the general population, and are comparable to non-deployed soldiers. Fatalities from PE are not uncommon, and vigilance among clinicians remains warranted. Trauma followed by prolonged air evacuation or ground transport during military operations may represent unique interactive risk factors for venous thromboembolism.

Fatal meningitis in a previously healthy young adult caused by Streptococcus pneumoniae serotype 38: an emerging serotype?

BACKGROUND: In December 2001, a fatal case of pneumococcal meningitis in a Marine Corps recruit was identified. As pneumococcal vaccine usage in recruit populations is being considered, an investigation was initiated into the causative serotype. CASE PRESENTATION: Traditional and molecular methods were utilized to determine the serotype of the infecting pneumococcus. The pneumococcal isolate was identified as serotype 38 (PS38), a serotype not covered by current vaccine formulations. The global significance of this serotype was explored in the medical literature, and found to be a rare but recognized cause of carriage and invasive disease. CONCLUSION: The potential of PS38 to cause severe disease is documented in this report. Current literature does not support the hypothesis that this serotype is increasing in incidence. However, as we monitor the changing epidemiology of pneumococcal illness in the US in this conjugate era, PS38 might find a more prominent and concerning niche as a replacement serotype.

Sudden death in young adults: a 25-year review of autopsies in military recruits.

BACKGROUND: Sudden death among military recruits is a rare but devastating occurrence. Because extensive medical data are available on this cross-sectional and diverse population, identification of the underlying causes of sudden death may promote health care policy to reduce the incidence of sudden death. OBJECTIVE: To determine the causes of nontraumatic sudden death among a cohort of military recruits. DESIGN: Retrospective cohort study using demographic and autopsy data from the Department of Defense Recruit Mortality Registry. SETTING: Basic military training. PATIENTS: All nontraumatic sudden deaths from a monitored 6.3 million men and women age 18 to 35 years. MEASUREMENTS: Descriptive analysis, crude mortality rates of causes of sudden death, and frequency of events as a function of cause of death. RESULTS: Of 126 nontraumatic sudden deaths (rate, 13.0/100,000 recruit-years), 108 (86%) were related to exercise. The most common cause of sudden death was an identifiable cardiac abnormality (64 of 126 recruits [51%]); however, a substantial number of deaths remained unexplained (44 of 126 recruits [35%]). The predominant structural cardiac abnormalities were coronary artery abnormalities (39 of 64 recruits [61%]), myocarditis (13 of 64 recruits [20%]), and hypertrophic cardiomyopathy (8 of 64 recruits [13%]). An anomalous coronary artery accounted for one third (21 of 64 recruits) of the cases in this cohort, and, in each, the left coronary artery arose from the right (anterior) sinus of Valsalva, coursing between the pulmonary artery and aorta. LIMITATIONS: This cohort underwent a preenlistment screening program that included history and physical examination; this may have altered outcomes. CONCLUSIONS: Cardiac abnormalities are the leading identifiable cause of sudden death among military recruits; however, more than one third of sudden deaths remain unexplained after detailed medical investigation.