Publications by authors named "James D Escobar"

8 Publications

  • Page 1 of 1

Association of Sickle Cell Trait on Career and Operational Outcomes in the United States Air Force.

Mil Med 2021 Jun 12. Epub 2021 Jun 12.

Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.

Introduction: Sickle cell trait (SCT) is a heterozygotic state defined by having one normal hemoglobin gene and one sickle hemoglobin gene. Individuals with SCT are at increased risk for negative health outcomes during intense physical exertion, especially in hot climates and high-elevation locations, or when dehydrated. The U.S. Air Force mitigates this risk through universal screening after accession followed by education of SCT-positive airmen. Airmen who are SCT positive but remain asymptomatic are not restricted in occupation choice or deployment/duty locations based on their SCT status. Previous studies have analyzed the relationship between SCT and health and fitness outcomes. The objective of this study was to analyze the relationship between SCT and career and operational outcomes in a large cohort of airmen and secondarily to analyze the relationship between hemoglobin S (HgbS) percentage and these outcomes.

Methods: This is a retrospective cohort study of all recruits who entered U.S. Air Force (USAF) Basic Military Training (BMT) between January 2009 and December 2013. The SCT status was assessed through a sickle solubility test. Hemoglobin electrophoresis permitted subgroup analysis of SCT-positive individuals by HgbS percentage. The following career and operational outcomes were assessed: BMT graduation; retention at 4 and 6 years; promotion to the rank of staff sergeant by 4 and 6 years; overseas deployment and number of deployments within 6 years; and high-elevation assignment and cumulative months at a high-elevation assignment within 6 years. Multivariable logistic regression was used to assess all binary outcomes, controlling for age, sex, and race, to produce adjusted odds ratios (aORs) with 95% confidence intervals (CIs). Multivariable Poisson regression was used to assess cumulative count outcomes and to produce adjusted incidence rate ratios (aIRRs) with 95% CIs. Attrition from BMT by SCT status was also assessed as a hazards function using the Kaplan-Meier approach with Cox proportional hazards.

Results: A total of 180,355 civilians entered USAF BMT during the 5-year surveillance period, of whom 169,837 graduated and had data available for analysis. Compared to their SCT-negative peers, SCT-positive airmen (n = 1,697) had 26% lower adjusted odds of promotion to staff sergeant within 4 years of BMT graduation (aOR = 0.74; 95% CI: 0.59-0.92) and served less time at a high-elevation assignment during their first 6 years (aIRR = 0.88; 95% CI: 0.85-0.91). The SCT status was not associated with statistically significant differences in BMT graduation, retention at 4 and 6 years, promotion to staff sergeant by 6 years, likelihood or number of overseas deployments, and likelihood of ever working at a high-elevation assignment. Retention at 4 and 6 years was inversely associated with HgbS percentage.

Conclusions: SCT-positive and SCT-negative airmen had similar career and operational outcomes, with two exceptions: SCT-positive airmen were less likely to be promoted to staff sergeant within 4 years, and they spent less time at a high-elevation location during their first 6 years of service. The underlying explanation of these findings should be explored with an aim to support SCT-positive airmen and to reduce potentially unwarranted discrepancies. Efforts should continue to reduce the stigma associated with SCT.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
June 2021

Malignancy in U.S. Air Force fighter pilots and other officers, 1986-2017: A retrospective cohort study.

PLoS One 2020 22;15(9):e0239437. Epub 2020 Sep 22.

Public Health and Preventive Medicine Department, U.S. Air Force School of Aerospace Medicine, Wright-Patterson Air Force Base, Ohio, United States of America.

Objective: This study sought to determine the incidence rates of cancer, overall and by site, among active component U.S. Air Force fighter pilots, and to compare the rates with those in other active component Air Force officers.

Methods: Using a matched retrospective cohort design, U.S. Air Force fighter pilots were compared with other commissioned officers who entered active component service between 1 January 1986 and 31 December 2006. The cohort was followed for cancer diagnoses in TRICARE and the Veterans Health Administration from 1 October 1995 through 31 December 2017. Fighter pilots and non-fighter pilot officers were compared after matching on sex, age at first observation (15 age groups), and age at last observation (15 age groups). Sex-stratified overall and site-specific cancer rates were compared with matched Poisson regression to determine incidence rate ratios with 95% confidence intervals.

Results: During 1,412,590 person-years of follow-up, among the study population of 88,432 service members (4,949 fighter pilots and 83,483 matched officers), 977 incident cancer cases were diagnosed (86 in fighter pilots and 891 in matched officers). Male fighter pilots and matched officers had similar rates of all malignant cancers (RR = 1.04; 95% CI: 0.83-1.31) and of each cancer site. Female fighter pilots and matched officers also had similar rates of all malignant cancers (RR = 0.99; 95% CI: 0.25-4.04).

Discussion: In the active component U.S. Air Force, fighter pilots and their officer peers had similar overall and site-specific cancer rates.
View Article and Find Full Text PDF

Download full-text PDF

November 2020

Evaluation of serological testing for Lyme disease in Military Health System beneficiaries in Germany, 2013-2017.

MSMR 2019 Aug;26(8):22-26

Lyme disease diagnostic workups conducted on active and retired U.S. service members and their dependents at U.S. Air Force military treatment facilities (MTFs) in Germany between 2013 and 2017 were assessed to determine the appropriateness of laboratory testing and antibiotic prescriptions. Of the 1,176 first-tier immunoassays, 1,114 (94.7%) were negative, and of the 285 immunoglobulin M (IgM) immunoblots, 242 (84.9%) followed a negative first-tier assay or were performed without an antecedent first-tier assay. Eighty-three positive IgM immunoblot tests were adjudicated using modified published criteria, of which 40 (48.2%) were deemed false positives. Thirtytwo patients with false-positive tests were treated with an antibiotic. Additionally, 30 patients with uncomplicated erythema migrans could have been treated without laboratory confirmation. Understanding the use and limitations of 2-tier diagnostic criteria, as well as the common pitfalls in diagnosing Lyme disease, may help prevent overdiagnosis, reduce unnecessary testing, and promote antibiotic stewardship.
View Article and Find Full Text PDF

Download full-text PDF

August 2019

Reported vectorborne and zoonotic diseases, U.S. Air Force, 2000-2011.

MSMR 2012 Oct;19(10):11-2; discussion 12-4

United States Air Force School of Aerospace Medicine, Department of Public Health and Preventive Medicine, Epidemiology Consult Service, Wright-Patterson Air Force Base, Ohio, USA.

During 2000-2011, U.S. Air Force Public Health Officers reported 770 cases of vectorborne and zoonotic diseases diagnosed at Air Force medical treatment facilities. Cases of Lyme disease accounted for 70 percent (n=538) of all cases and most cases of Lyme disease (57%) were reported from bases in the northeastern U.S. and in Germany. The annual numbers of reported Lyme disease cases were much higher during the last four years than earlier in the surveillance period. The next most commonly reported events were malaria (74 cases), Rocky Mountain spotted fever (RMSF) (41), Q fever (33), dengue (23), and leishmaniasis (20). These five infections and Lyme disease accounted for 95 percent of the reported conditions. Military service members accounted for a majority of the reported cases for most of the conditions, but family members and retirees accounted for most of the cases of Lyme disease and RMSF. Most reports of vectorborne and zoonotic diseases did not include mentions of recent travel.
View Article and Find Full Text PDF

Download full-text PDF

October 2012

Norovirus outbreak associated with person-to-person transmission, U.S. Air Force Academy, July 2011.

MSMR 2011 Nov;18(11):2-5

United States Air Force School of Aerospace Medicine, Epidemiology Consult Service, Wright-Patterson AFB, Ohio, USA.

In July 2011, the U.S. Air Force School of Aerospace Medicine (USAFSAM) Epidemiology Consult Service investigated an ongoing outbreak of acute gastrointestinal (GI) illness--characterized by vomiting, nausea, diarrhea, and stomach cramps--that affected cadets and support personnel at a field training location at the U.S. Air Force Academy. Six outbreak-related stool specimens were confirmed by RT-PCR to be infected with norovirus, genogroup I. Overall, 290 cases (suspected and confirmed) of norovirus-related GI illness were recorded; the estimated attack rate among 1,359 cadets was 18%. The investigation suggested that norovirus was introduced into the field dining facility by one or more food service workers, possibly transmitted via common use serving utensils, and then further spread among cadets by person-to-person contact. Numbers of new cases sharply declined after ill cadets were segregated in separate tents for convalescence, and after all cadets moved from field billets (i.e., tents) to dormitories after completing the field training.
View Article and Find Full Text PDF

Download full-text PDF

November 2011

Novel Influenza A (H1N1) outbreak at the U.S. Air Force Academy: epidemiology and viral shedding duration.

Am J Prev Med 2010 Feb 21;38(2):121-6. Epub 2009 Oct 21.

2355 Faculty Drive, Room 2N286, U.S. Air Force Academy, Colorado Springs CO 80840, USA.

Background: The U.S. Air Force Academy is an undergraduate institution that educates and trains cadets for military service. Following the arrival of 1376 basic cadet trainees in June 2009, surveillance revealed an increase in cadets presenting with respiratory illness. Specimens from ill cadets tested positive for novel influenza A (H1N1 [nH1N1])-specific ribonucleic acid (RNA) by real-time reverse transcriptase-polymerase chain reaction.

Purpose: The outbreak epidemiology, control measures, and nH1N1 shedding duration are described.

Methods: Case patients were identified through retrospective and prospective surveillance. Symptoms, signs, and illness duration were documented. Nasal-wash specimens were tested for nH1N1-specific RNA. Serial samples from a subset of 53 patients were assessed for presence of viable virus by viral culture.

Results: A total of 134 confirmed and 33 suspected cases of nH1N1 infection were identified with onset date June 25-July 24, 2009. Median age of case patients was 18 years (range, 17-24 years). Fever, cough, and sore throat were the most commonly reported symptoms. The incidence rate among basic cadet trainees during the outbreak period was 11%. Twenty-nine percent (31/106) of samples from patients with temperature <100 degrees F and 19% (11/58) of samples from patients reporting no symptoms for > or = 24 hours contained viable nH1N1 virus. Of 29 samples obtained 7 days from illness onset, seven (24%) contained viable nH1N1 virus.

Conclusions: In the nH1N1 outbreak under study, the number of cases peaked 48 hours after a social event and rapidly declined thereafter. Almost one quarter of samples obtained 7 days from illness onset contained viable nH1N1 virus. These data may be useful for future investigations and in scenario planning.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
February 2010

Fast food and neighborhood stroke risk.

Ann Neurol 2009 Aug;66(2):165-70

University of Michigan Medical School, Ann Arbor, MI, USA.

Objective: To investigate the association between the number of fast food restaurants and ischemic stroke in neighborhoods.

Methods: This work was a prespecified part of the Brain Attack in Corpus Christi (BASIC) project. Ischemic stroke cases were prospectively ascertained in Nueces County, Texas. Home addresses were geocoded and used to establish the census tract for each stroke case. Census tracts were used as proxies for neighborhoods (n = 64). Using a standard definition, fast food restaurants were identified from a commercial list. Poisson regression was used to study the association between the number of fast food restaurants in the neighborhood, using a 1-mile buffer around each census tract, and the risk of stroke in the neighborhood. Models were adjusted for demographics and neighborhood socioeconomic status (SES).

Results: There were 1,247 completed ischemic strokes from January 2000 through June 2003 and 262 fast food restaurants. The median number of fast food restaurants per census tract including buffer was 22 (interquartile range, 12-33). Adjusting for neighborhood demographics and SES, the association of fast food restaurants with stroke was significant (p = 0.02). The association suggested that the risk of stroke in a neighborhood increased by 1% for every fast food restaurant (relative risk, 1.01; 95% confidence interval [CI], 1.00-1.01). The relative risk of stroke comparing neighborhoods in the 75th to the 25th percentile of the distribution of fast food restaurants was 1.13 (95% CI, 1.02-1.25).

Interpretation: Controlling for demographic and SES factors, there was a significant association between fast food restaurants and stroke risk in neighborhoods in this community-based study.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
August 2009

Ambient air pollution and risk for ischemic stroke and transient ischemic attack.

Ann Neurol 2008 Jul;64(1):53-9

Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI 48109-2029, USA.

Objective: Data on the association between air pollution and cerebrovascular disease in the United States are limited. The objective of this study was to investigate the association between short-term exposure to ambient air pollution and risk for ischemic cerebrovascular events in a US community.

Methods: Daily counts of ischemic strokes/transient ischemic attacks (TIAs) (2001-2005) were obtained from the population-based Brain Attack Surveillance in Corpus Christi (BASIC) Project. Daily particulate matter less than 2.5microm in diameter (PM(2.5)), ozone (O(3)), and meteorological data were obtained from Texas Commission on Environmental Quality. To examine the association between PM(2.5) and stroke/TIA risk, we used Poisson regression. Separate models included same-day PM(2.5), PM(2.5) lagged 1 to 5 days, and an averaged lag effect. All models were adjusted for temperature, day of week, and temporal trends in stroke/TIA. The effects of O(3) were also investigated.

Results: Median PM(2.5) was 7.0microg/m(3) (interquartile range, 4.8-10.0microg/m(3)). There were borderline significant associations between same-day (relative risk [RR], 1.03; 95% confidence interval [CI], 0.99-1.07 for an interquartile range increase in PM(2.5)) and previous-day (RR, 1.03; 95% CI, 1.00-1.07) PM(2.5) and stroke/TIA risk. These associations were independent of O(3), which demonstrated similar associations with stroke/TIA risk (same-day RR, 1.02; 95% CI, 0.97-1.08; previous-day RR, 1.04; 95% CI, 0.99-1.09).

Interpretation: We observed associations between recent PM(2.5) and O(3) exposure and ischemic stroke/TIA risk even in this community with relatively low pollutant levels. This study provides data on environmental exposures and stroke risk in the United States, and suggests future research on ambient air pollution and stroke is warranted.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
July 2008