Bryant J. Webber

Prevalence of and Risk Factors for Autopsy-Determined Atherosclerosis Among US Service Members, 2001-2011

CONTEXT Autopsies of US service members killed in the Korean and Vietnam wars demonstrated that atherosclerotic changes in the coronary arteries can appear early in the second and third decades of life, long before ischemic heart disease becomes clinically apparent. OBJECTIVE To estimate the current prevalence of coronary and aortic atherosclerosis in the US armed forces. DESIGN, SETTING, AND PARTICIPANTS Cross-sectional study of all US service members who died of combat or unintentional injuries in support of Operations Enduring Freedom and Iraqi Freedom/New Dawn between October 2001 and August 2011 and whose cardiovascular autopsy reports were available at the time of data collection in January 2012. Prevalence of atherosclerosis was analyzed by various demographic characteristics and medical history. Classifications of coronary atherosclerosis severity were determined prior to data analysis and designed to provide consistency with previous military studies: minimal (fatty streaking only), moderate (10%-49% luminal narrowing of ≥1 vessel), and severe (≥50% narrowing of ≥1 vessel). MAIN OUTCOME MEASURES Prevalence of coronary and aortic atherosclerosis in the US armed forces and by age, sex, self-reported race/ethnicity, education, occupation, service branch and component, military rank, body mass index at military entrance, and International Classification of Diseases, Ninth Revision, Clinical Modification, diagnoses of cardiovascular risk factors. RESULTS Of the 3832 service members included in the analysis, the mean age was 25.9 years (range, 18-59 years) and 98.3% were male. The prevalence of any coronary atherosclerosis was 8.5% (95% CI, 7.6%-9.4%); severe coronary atherosclerosis was present in 2.3% (95% CI, 1.8%-2.7%), moderate in 4.7% (95% CI, 4.0%-5.3%), and minimal in 1.5% (95% CI, 1.1%-1.9%). Service members with atherosclerosis were significantly older (mean [SD] age, 30.5 [8.1] years) than those without (mean [SD] age, 25.3 [5.6] years; P < .001). Comparing atherosclerosis prevalence among with those with no cardiovascular risk factor diagnoses (11.1% [95% CI, 10.1%-12.1%]), there was a greater prevalence among those with a diagnosis of dyslipidemia (50.0% [95% CI, 30.3%-69.7%]; age-adjusted prevalence ratio [PR], 2.09 [95% CI, 1.43-3.06]), hypertension (43.6% [95% CI, 27.3%-59.9%]; age-adjusted PR, 1.88 [95% CI, 1.34-2.65]), or obesity (22.3% [95% CI, 15.9%-28.7%]; age-adjusted PR, 1.47 [95% CI, 1.10-1.96]), but smoking (14.1% [95% CI, 8.0%-20.2%]) was not significantly associated with a higher prevalence of atherosclerosis (age-adjusted PR, 1.12 [95% CI, 0.73-1.74]). CONCLUSION Among deployed US service members who died of combat or unintentional injuries and received autopsies, the prevalence of atherosclerosis varied by age and cardiovascular risk factors.

Lower obesity rate during residence at high altitude among a military population with frequent migration: a quasi experimental model for investigating spatial causation.

We sought to evaluate whether residence at high altitude is associated with the development of obesity among those at increased risk of becoming obese. Obesity, a leading global health priority, is often refractory to care. A potentially novel intervention is hypoxia, which has demonstrated positive long-term metabolic effects in rats. Whether or not high altitude residence confers benefit in humans, however, remains unknown. Using a quasi-experimental, retrospective study design, we observed all outpatient medical encounters for overweight active component enlisted service members in the U.S. Army or Air Force from January 2006 to December 2012 who were stationed in the United States. We compared high altitude (>1.96 kilometers above sea level) duty assignment with low altitude (<0.98 kilometers). The outcome of interest was obesity related ICD-9 codes (278.00-01, V85.3x-V85.54) by Cox regression. We found service members had a lower hazard ratio (HR) of incident obesity diagnosis if stationed at high altitude as compared to low altitude (HR 0.59, 95% confidence interval [CI] 0.54–0.65; p<0.001). Using geographic distribution of obesity prevalence among civilians throughout the U.S. as a covariate (as measured by the Centers for Disease Control and Prevention and the REGARDS study) also predicted obesity onset among service members. In conclusion, high altitude residence predicts lower rates of new obesity diagnoses among overweight service members in the U.S. Army and Air Force. Future studies should assign exposure using randomization, clarify the mechanism(s) of this relationship, and assess the net balance of harms and benefits of high altitude on obesity prevention.

Improving Diagnostic Accuracy and Efficiency of Suspected Bone Stress Injuries: Algorithm and Clinical Prediction Rule.

Context: Lower extremity stress fractures among athletes and military recruits cause significant morbidity, fiscal costs, and time lost from sport or training. During fiscal years (FY) 2012 to 2014, 1218 US Air Force trainees at Joint Base San Antonio–Lackland, Texas, were diagnosed with stress fracture(s). Diagnosis relied heavily on bone scans, often very early in clinical course and often in preference to magnetic resonance imaging (MRI), highlighting the need for an evidence-based algorithm for stress injury diagnosis and initial management. Evidence Acquisition: To guide creation of an evidence-based algorithm, a literature review was conducted followed by analysis of local data. Relevant articles published between 1995 and 2015 were identified and reviewed on PubMed using search terms stress fracture, stress injury, stress fracture imaging, and stress fracture treatment. Subsequently, charts were reviewed for all Air Force trainees diagnosed with 1 or more stress injury in their outpatient medical record in FY 2014. Study Design: Clinical review. Level of Evidence: Level 4. Results: In FY 2014, 414 trainees received a bone scan and an eventual diagnosis of stress fracture. Of these scans, 66.4% demonstrated a stress fracture in the symptomatic location only, 21.0% revealed stress fractures in both symptomatic and asymptomatic locations, and 5.8% were negative in the symptomatic location but did reveal stress fracture(s) in asymptomatic locations. Twenty-one percent (18/85) of MRIs performed a mean 6 days (range, 0- 21 days) after a positive bone scan did not demonstrate any stress fracture. Conclusion: Bone stress injuries in military training environments are common, costly, and challenging to diagnose. MRI should be the imaging study of choice, after plain radiography, in those individuals meeting criteria for further workup.

Notes from the Field: Outbreak of Hand, Foot, and Mouth Disease Caused by Coxsackievirus A6 Among Basic Military Trainees - Texas, 2015.

On July 7, 2015, a man aged 22 years reported to sick call during basic military training at Lackland Air Force Base (AFB), Texas. He had erythematous, crusted papulovesicular lesions on the extensor surfaces of the upper and lower extremities. The patient was afebrile and otherwise well, and was evaluated later that day by the dermatology service. A viral infection was considered most likely because of the patients age, absence of fever or constitutional symptoms, and the distribution and morphology of the lesions. The initial differential diagnosis included Henoch-Schönlein purpura, parvovirus B19, and Rocky Mountain spotted fever. However, the clinical signs, including the unique morphology and distribution of grouped vesicles and papules was suggestive of hand, foot, and mouth disease (HFMD), although the patient did not have oral lesions and reported no contact with another person with HFMD. A viral culture and punch biopsy of one of the lesions were obtained.

Screening for Sickle-Cell Trait at Accession to the United States Military

Condition Definition SCT is a heterozygotic carrier state in which an individual has one copy of the normal HbA gene and one copy of the HbS variant. Commercial tests for SCT have been available since the early 1970s. The sickle solubility test qualitatively detects the presence of HbS by precipitating sickle hemoglobin in the presence of an oxygen depleting reagent. With a sensitivity approaching 99% and a specificity of 100%, sickle solubility provides an accurate screening method. The hemoglobin electrophoresis test is a confirmatory test that quantifies the percentage of HbS and is therefore able to distinguish among the HbS disorders, such as SCT or sicklecell disease. According to the 59th Clinical Lab Flight at Joint Base San Antonio-Lackland, Texas (oral communication, November 2013), the U.S. Air Force (USAF) spends

Varicella seroepidemiology in United States air force recruits: A retrospective cohort study comparing immunogenicity of varicella vaccination and natural infection

4.86 on the sickle solubility test and

Bilateral Lower Extremity Inflammatory Lymphedema in Air Force Basic Trainees: Clinical and Epidemiologic Study of a New Disease Entity

9.41 on the hemoglobin electrophoresis test.

Measles, Mumps, and Rubella Titers in Air Force Recruits: Below Herd Immunity Thresholds?

BACKGROUND/OBJECTIVES Infection with varicella zoster virus (VZV) produces lifelong immunity, but duration of post-vaccination immunity has not been established. The purpose of this study is to determine if a difference exists in the long-term seropositivity of anti-VZV antibodies in a cohort of young adults who were vaccinated against varicella as compared to a similar cohort with a history of chickenpox disease, and to determine which variables best predict waning seropositivity following varicella vaccination. METHODS This retrospective cohort study captures immunization and serology data from approximately 10,000 recruits who entered basic military training between January 1, 2008, and December 31, 2015, and who have childhood immunization records in the Air Force Aeromedical Services Information Management System. Varicella vaccine immunogenicity was determined relative to the immunogenicity of chickenpox disease, as measured by multiplex flow immunoassay. Among vaccine recipients, waning seroimmunity was modeled and adjusted for several important covariates. RESULTS Basic military trainees who received varicella vaccine in childhood were 24% less likely to be seropositive to VZV than trainees who were exempt from vaccine due to a history of chickenpox disease. There was no significant difference in seropositivity between male and female trainees. The odds of a vaccinated trainee being seropositive to VZV decreased by 8% with each year elapsed since vaccination. Seroprevalence declined below estimated herd immunity thresholds in vaccinated trainees born after 1994, and in the cohort as a whole for trainees born after 1995. CONCLUSION Despite prior vaccination, seroimmunity in a large cohort of young adults unexposed to wild-type VZV failed to meet the estimated threshold for herd immunity. If vaccination in accordance with the current US VZV vaccination schedule is inadequate to maintain herd immunity, young adults not previously exposed to wild-type VZV may be at increased risk for varicella outbreaks.

Contraceptive prescriptions for US servicewomen, 2008–2013

IMPORTANCE This observational study characterizes a new clinical condition identified in 55 military trainees. OBJECTIVE To determine the incidence and underlying cause of bilateral lower extremity inflammatory lymphedema in Air Force basic trainees. DESIGN, SETTING, AND PARTICIPANTS An observational study was conducted at Lackland Air Force Base in San Antonio, Texas. Participants included 14 243 Air Force basic trainees who entered training between September 2011 and January 2012 and the 55 trainees (0.4%) who developed bilateral lower extremity inflammatory lymphedema that occurred during the 8½-week basic training course. Two modifiable risk factors were evaluated: vaccine reaction and newly issued military footwear (combat boots and boot socks). INTERVENTIONS During November 2011, all new trainees wore only white socks and running shoes rather than the issued military footwear. During December 2011 and January 2012, the scheduled administration of tetanus/diphtheria/acellular pertussis and meningococcal vaccines, respectively, was delayed by 1 week for all new trainees. A full medical record review was conducted for every confirmed case of bilateral lower extremity inflammatory lymphedema. MAIN OUTCOMES AND MEASURES Identification of incident cases, symptom onset, antimicrobial treatment, immunization reaction, laboratory studies, specialty referral, and biopsy. RESULTS Fifty-four of the 55 incident cases (98%) of bilateral lower extremity inflammatory lymphedema occurred during the first 120 hours of training. Alterations in the timing of the military footwear used and selected vaccine administration had no effect on the incidence of new cases. Two participants (4%) experienced symptom onset before receipt of the vaccines. Oral antimicrobial medications were not found to speed symptom resolution compared with conservative treatment measures (P = .34). One incident case was diagnosed as leukocytoclastic vasculitis by tissue examination. CONCLUSIONS AND RELEVANCE Multiple training-related risk factors were ruled out as sources of bilateral lower extremity inflammatory lymphedema. Cases are likely secondary to prolonged standing with resultant gravity-dependent venous congestion and inflammatory vasculitis. The potential roles of undiagnosed venous reflux disease and the military physical training environment in these cases remain to be elucidated.

Concurrent bilateral femoral neck stress fractures in a military recruit: a case report

INTRODUCTION Preventable diseases like measles and mumps are occurring with increasing frequency in the U.S. despite the availability of an effective vaccine. Given concern that an outbreak may occur among military recruits, we compared serologic evidence of immunity to measles, mumps, and rubella among military recruits with known herd immunity thresholds and determined whether the current Department of Defense policy of presuming mumps immunity based on measles and rubella titers is reliable. METHODS Serum antibody levels for measles, mumps, and rubella were obtained from all new recruits upon arrival at Joint Base San Antonio-Lackland, Texas, from 25 April 2013 through 24 April 2014. Seroprevalence of each disease was assessed by age and sex, and concordance between mumps titers and measles and rubella titers was calculated. Data analysis was performed in 2014-2015. RESULTS Among 32,502 recruits, seroprevalences for measles, mumps, and rubella antibodies were 81.6%, 80.3%, and 82.1%, respectively. Of the 22,878 recruits seropositive for both measles and rubella antibodies, 87.7% were also seropositive for mumps. CONCLUSIONS Seroprevalences for measles, mumps, and rubella antibodies among a large cohort of recruits entering U.S. Air Force basic training were generally lower than levels required to maintain herd immunity. In order to reduce the incidence of mumps infections, the Department of Defense should consider obtaining antibody titers for measles, mumps, and rubella and vaccinating all individuals susceptible to one or more of the viruses.