Abstract
Introduction
Sickle cell trait (SCT) affects an estimated 5.02% of non-Hispanic blacks, 1.08% of Hispanics, and 0.1% of Whites in the U.S. military. Policies for SCT screening and occupational restrictions vary by service. Population-based studies of SCT with quantification of military-relevant outcomes are lacking.
Methods
The study design was a retrospective cohort of 15,081 SCT-positive versus 60,320 SCT-negative U.S. active duty personnel enlisted from 1992 to 2012 and followed through 2013. Military-relevant outcome included number and days of deployment, length of service, and cause of death.
Results
SCT-positive versus SCT-negative service members experienced more deployments (p < 0.01) and longer number of days deployed for all services, especially the Army (p < 0.001). The median length of service was longer for SCT-positive service members stratified by service and by gender (p < 0.05). The adjusted risk of length of service greater than 5 yr by SCT status was 1.37 (95% confidence interval 1.31–1.43) with greater than a three-fold higher risk in the Navy and Air Force compared with the Army. Crude mortality rate was not significantly different by SCT status, although deaths due to suicide, self-directed violence, and other non-specific causes were more common in SCT-positive service members.
Conclusion
We found that SCT-positive service members deployed more frequently, for greater lengths of time, and remained in service longer. No significant difference in crude mortality ratio was discovered. Additional research on military-relevant outcomes and a cost-effectiveness analysis of SCT screening practices are needed to inform evidence-based SCT enlistment policies.
Keywords: Sickle Cell Trait; Deployment; Retention; Mortality; Length of Service, Military
Introduction
Sickle cell disease (SCD), affecting as many as 100,000 persons in the United States, is typically characterized by numerous acute and chronic complications resulting in higher levels of morbidity and mortality as compared with those without SCD.1–4 Less understood at either the population or the individual level are the acute or chronic effects of the heterozygous state (HbAS) of sickle cell trait (SCT) on health. Long considered a benign condition by the general medical community, case reports and cohort studies are strengthening the association of SCT with deleterious health outcomes.5,6,7
Since 9/11, the U.S. military has experienced an unprecedented level of activity with more intensive and prolonged use of manpower with 1.4 million active duty uniformed members, which is a decrease in one-third from the 2.1 million service members at the 1991 end of the Cold War. This reduction has resulted in longer and repeated deployments, particularly for the Army and the Marine Corps.8 Maintenance of force readiness and structure requires recruiting new candidates, reducing attrition, and retaining experienced service members.
Recruiting and retention goals are adjusted annually based on projected force needs. In 2015, approximately 186,000 enlistees were required for all four active and six reserve components.9,10 Historically, heavy attrition rates have been documented among recruits, especially in the first 12 mo of service. Applicants to all services (Army, Navy, Air Force, and Marine Corps) are screened against Department of Defense standardized medical guidelines.9 The individual services are responsible for maintaining fitness and readiness for worldwide deployment11 and determine service-specific entrance requirements. Applicants or members may be subject to additional screening or standards for certain occupations, skill training, or retention in service.12–15
The U.S. military conducts periodic analyses of health surveillance data that include SCT and its associations with disease outcomes. SCT affects an estimated 7–9% of non-Hispanic Blacks, 0.5% of Hispanics, to 0.2% of Whites in the U.S. general population versus 5.02% of non-Hispanic Blacks, 1.08% of Hispanics, and 0.1% of Whites in the U.S. military.7,16 Military policy on SCT screening and military occupation restrictions for SCT+ service members has been both dynamic and inconsistent. After a series of training-related deaths in recruits in the late 1960s, the U.S. military initiated SCT-specific screening in new recruits. Applicants discovered to be SCT+ were restricted from certain military occupations. Although restrictions have since been gradually removed for some occupational specialties, the Navy and Air Force continue SCT screening. The Army discontinued universal SCT screening procedures in 1991 and implemented universal precautions to reduce injuries among all soldiers.17 The purpose of this study is to explore the associations between SCT and selected military and individually relevant outcomes, which include deployment, length of service, and mortality.
Methods
Study subjects
We conducted a retrospective cohort study among U.S. active duty, enlisted, service members from 1992 to 2012 using the existing Department of Defense Military Healthcare System databases. Eligible cases were identified in the following two ways: (1) medical encounter SCT diagnosis (ICD-9-CM 282.5) in ambulatory or hospitalized encounter records provided by Armed Forces Health Surveillance Center or (2) documentation of a positive laboratory SCT test result in the existing Military Health System HL-7 laboratory database from 2006 to 2012 provided by the Navy and Marine Corps Public Health Center. Unexposed subjects consisted of a random sample of active duty service members during the same time period with no documentation of SCT diagnosis. Four unexposed were matched to every one SCT-positive subject on gender, racial ethnic group (non-Hispanic White, non-Hispanic Black, Hispanic, and non-Hispanic Other/Unknown), service branch, as well as quarter and year of enlistment. Demographic data provided by Armed Forces Health Surveillance Center on SCT cases and controls included the following: quarter of enlistment, age at enlistment, gender, race/ethnicity, country of origin, home of record by region, location of enlistment (basic training site) by region, military occupation category, and date of discharge. Outcomes of military and individual relevance through 2013 were also provided to include the number of deployments, total number of days deployed, length of service from enlistment to separation, and causes of death by SCT status.
Statistical analysis
We first compared the distribution of selected demographic variables at enlistment by SCT-positive versus SCT-negative status using the Chi-square test. Quintiles of total days of deployment were examined and compared by SCT status using the Chi-square test. Additionally, median and interquartile (25–75%) range (IQR) of length of service by SCT status were reported and compared using the Wilcoxon rank sum test. Cause of death for study subjects was determined by the Armed Forces Medical Examiner’s office and categorized as follows: accident, cardiovascular disease, homicide, suicide/self-directed violence, motor vehicle accident, war operations, and other. The association of SCT status with length of service (>5 yr versus ≤5 yr) was calculated using multivariable logistic regression yielding adjusted odds ratios (OR) and 95% confidence intervals (CIs). The following potential confounders were considered for inclusion in our multivariable model: racial/ethnic group, gender, age, service branch, occupation, number of deployments, home region, quarter year of enlistment, and enlistment region. Stepwise variable selection was performed (elimination if p > 0.1) to provide the most parsimonious model. A p-value of < 0.05 was considered statistically significant. All analyses were conducted using SAS, (Version 9.3), Cary, NC.
The Uniformed Services University of the Health Sciences Institutional Review Board approved this protocol. The study was funded by an Interagency Agreement with the National Heart, Lung and Blood Institute.
Results
Table I describes the demographic characteristics for SCT-positive versus SCT-negative enlistees who were matched on gender, race, and branch of service. The following demographic attributes were slightly overrepresented among SCT-positive subjects: age at enlistment over 25 yr, communications/intelligence occupations, ever deployed, home region (northeast, mid-Atlantic, and southeast), enlistment region (southeast and midwest), non-Hispanic Whites, Hispanics, males, and Navy service members.
Table I.
Comparison of Demographics at Enlistment to Separation Among U.S. Military Members by SCT-Negative (−) Versus SCT-Positive (+) Status
| SCT− n (%) | SCT+ n (%) | p-value | |
|---|---|---|---|
| Gendera | |||
| Female | 20,016 (33.2) | 5,004 (33.2) | – |
| Male | 40,304 (66.8) | 10,077 (66.8) | |
| Racea | |||
| Non-Hispanic White | 2,711 (4.5) | 677 (4.5) | – |
| Non-Hispanic Black | 49,118 (81.4) | 12,281 (81.4) | |
| Non-Hispanic other | 3,444 (5.7) | 860 (5.7) | |
| Hispanic | 5,047 (8.4) | 1,263 (8.4) | |
| Age at enlistmenta | |||
| 18–19 yr | 33,190 (55.0) | 8,064 (53.5) | – |
| 20–24 yr | 21,979 (36.4) | 5,580 (37.0) | |
| 25–29 yr | 3,955 (6.6) | 1,077 (7.1) | |
| 30+ yr | 1,196 (2.0) | 360 (2.4) | |
| Service brancha | |||
| Army | 13,152 (21.8) | 3,277 (21.7) | – |
| Navy | 29,280 (48.5) | 7,327 (48.6) | |
| Air Force | 13,944 (23.1) | 3,488 (23.1) | |
| Marine | 3,944 (6.5) | 989 (6.6) | |
| Occupationb | |||
| Repair/engineer | 17,034 (28.2) | 4,241 (28.1) | <0.01 |
| Combat | 2,701 (4.5) | 549 (3.6) | |
| Armor/motor transport | 3,621 (6.0) | 906 (6.0) | |
| Communications/intelligence | 15,335 (25.4) | 4,246 (28.2) | |
| Health care | 5,121 (8.5) | 1,350 (9.0) | |
| Other | 16,508 (27.4) | 3,789 (25.1) | |
| Number of deployments | |||
| 0 | 34,651 (57.5) | 7,763 (51.5) | <0.01 |
| 1 | 15,320 (25.4) | 3,970 (26.3) | |
| 2+ | 10,349 (17.2) | 3,348 (22.2) | |
| Home region | |||
| Northeast | 5,780 (9.7) | 1,843 (12.3) | <0.01 |
| Mid-Atlantic | 6,146 (10.4) | 1,653 (11.1) | |
| Southeast | 18,736 (31.5) | 5,180 (34.6) | |
| North | 7,975 (13.4) | 1,695 (11.3) | |
| Southwest | 8,310 (14.0) | 1,935 (12.9) | |
| West | 5,411 (9.1) | 1,091 (7.3) | |
| Central | 7,038 (11.9) | 1,562 (10.4) | |
| Enlistment region | |||
| Southeast | 12,047 (20.3) | 3,201 (21.5) | <0.01 |
| Midwest | 28,504 (48.0) | 7,189 (48.3) | |
| Southwest | 15,072 (25.4) | 3,781 (25.4) | |
| West | 3,804 (6.4) | 706 (4.8) | |
| Quarter year of enlistment | |||
| January–March | 15,050 (25.0) | 3,775 (25.0) | 0.65 |
| April–June | 14,810 (24.6) | 3,741 (24.8) | |
| July–September | 18,450 (30.6) | 4,534 (30.1) | |
| October–December | 12,010 (20.0) | 3,031 (20.1) | |
aMatching variables.
bLast recorded occupation used 32,884.
Figure 1 plots the rate of the number of deployments for all services combined by SCT-positive versus SCT-negative status. The SCT-positive subjects experienced more deployments than SCT-negative subjects (p < 0.01). Similar findings were observed when subjects were restricted to the Army, Marine Corps, and Air Force, but not the Navy (results not shown).
Figure 1.
Distribution of the number of deployments among those deployed by SCT-positive versus SCT-negative status, p < 0.01. Note: 56.3% of study subjects did not deploy.
Table II shows the distribution of subjects by the total number of days deployed and SCT status.
Table II.
Distribution of Study Subjects by Total Days of Deployment (Quartiles) by SCT Status Negative (-) Versus Positive (+ )
| Deployment (d) | SCT– n (%) | SCT+ n (%) | p-value |
|---|---|---|---|
| All | |||
| 1–57 | 2,357 (9.2) | 670 (9.2) | <0.001 |
| 58–132 | 5,786 (22.6) | 1,547 (21.2) | |
| 133–187 | 6,322 (24.7) | 1,711 (23.4) | |
| >187 | 11,121 (43.5) | 3,370 (46.2) | |
| Army | |||
| 1–57 | 643 (11.4) | 173 (9.0) | <0.001 |
| 58–132 | 1,255 (22.2) | 374 (19.5) | |
| 133–187 | 1,069 (18.9) | 323 (19.8) | |
| >187 | 2,697 (47.6) | 1,051 (54.7) | |
| Navy | |||
| 1–57 | 1,225 (9.4) | 350 (10.1) | 0.609 |
| 58–132 | 2,500 (19.1) | 648 (18.7) | |
| 133–187 | 3,703 (28.3) | 978 (28.2) | |
| >187 | 5,664 (43.3) | 1,494 (43.1) | |
| Air Force | |||
| 1–57 | 372 (6.7) | 107 (7.2) | 0.587 |
| 58–132 | 1,840 (33.3) | 474 (31.7) | |
| 133–187 | 1,335 (24.1) | 356 (23.8) | |
| >187 | 1,984 (35.9) | 558 (37.3) | |
| Marine | |||
| 1–57 | 117 (9.0) | 40 (9.7) | 0.169 |
| 58–132 | 191 (14.7) | 51 (12.4) | |
| 133–187 | 215 (16.6) | 54 (13.1) | |
| >187 | 776 (59.7) | 267 (64.8) | |
Note: Deployment days presented in quartiles of days deployed for all deployed subjects. The lowest 1 percentile and the top 99th percentile were excluded so that each of the quartiles no longer represent 25% of the subjects.
For all services, SCT-positive subjects showed a slightly greater number of days deployed per subject compared with SCT-negative subjects (46.2% compared with 43.5%, respectively, with more than 187 d deployed) after excluding the bottom and top 1% of days deployed and without consideration of the length of military service. This finding was driven by data from the Army. There was no statistically significant difference in total days deployed for the Navy, Air Force, or Marines (p > 0.1).
Table III compares the median time in years from enlistment to separation by SCT status. The median length of service was longer for SCT-positive compared with SCT-negative males (4.1 versus 3.6 yr) and females (4.3 versus 3.5 yr), non-Hispanic racial groups, each branch of service, each occupation (except for repair/engineer), all deployment categories (including never and ever deployed), each home district region, enlistment (basic training) district, and each quarter of enlistment (p < 0.05).
Table III.
Median Length of Service Time (years) from Enlistment to Separation Among U.S. Military Members by SCT-Negative (−) Versus SCT-Positive (+ )
| SCT− | SCT + | |||||
|---|---|---|---|---|---|---|
| n | Median | IQR | n | Median | IQR | |
| Sex | ||||||
| Female | 20,016 | 3.5 | 4.7 | 50,04 | 4.3 | 6.2 |
| Male | 40,304 | 3.6 | 4.5 | 10,077 | 4.1 | 5.5 |
| Race | ||||||
| Non-Hispanic White | 2,711 | 3.6 | 4.0 | 677 | 3.8 | 4.5 |
| Non-Hispanic Black | 49,118 | 3.5 | 4.6 | 12,281 | 4.1 | 5.9 |
| Non-Hispanic others | 3,444 | 3.2 | 4.1 | 860 | 3.7 | 5.3 |
| Hispanic | 5,047 | 4.1 | 4.0 | 1,263 | 4.1 | 4.5 |
| Age at enlistment (yr) | ||||||
| 18–19 | 33,190 | 3.7 | 4.7 | 8,064 | 4.1 | 6.1 |
| 20–24 | 21,979 | 3.4 | 4.3 | 5,580 | 4.0 | 5.2 |
| 25–29 | 3,955 | 3.2 | 4.3 | 1,077 | 4.0 | 5.4 |
| 30+ | 1,196 | 3.4 | 4.1 | 360 | 3.8 | 4.4 |
| Service | ||||||
| Army | 13,152 | 3.0 | 4.0 | 3,277 | 5.1 | 6.5 |
| Navy | 29,280 | 3.6 | 4.6 | 7,327 | 3.9 | 5.0 |
| Air Force | 13,944 | 3.9 | 5.5 | 3,488 | 4.1 | 6.9 |
| Marine | 3,944 | 3.2 | 3.0 | 989 | 4.1 | 4.7 |
| Occupation | ||||||
| Repair/engineer | 17,034 | 4.1 | 4.0 | 4,241 | 4.1 | 4.8 |
| Combat | 2,701 | 3.5 | 3.6 | 549 | 5.1 | 6.9 |
| Armor/motor transport | 3,621 | 2.3 | 3.4 | 906 | 2.6 | 3.6 |
| Communication/intelligence | 15,335 | 4.1 | 5.0 | 4,246 | 5.1 | 6.5 |
| Health care | 5,121 | 4.5 | 5.0 | 1,350 | 5.4 | 6.2 |
| Others | 16,508 | 1.8 | 3.7 | 3,789 | 2.4 | 4.7 |
| Number of deployment | ||||||
| 0 | 34,651 | 1.9 | 3.1 | 7,763 | 2.4 | 3.1 |
| 1 | 15,320 | 4.9 | 4.3 | 3,970 | 5.2 | 4.9 |
| 2+ | 10,349 | 6.9 | 5.8 | 3,348 | 8.4 | 7.3 |
| Home region | ||||||
| Northeast | 5,780 | 4.0 | 4.7 | 1,843 | 4.5 | 6.3 |
| Mid-Atlantic | 6,146 | 3.7 | 4.5 | 1,653 | 4.2 | 5.8 |
| Southeast | 18,736 | 3.8 | 4.7 | 5,180 | 4.2 | 5.8 |
| North | 7,975 | 3.5 | 4.3 | 1,695 | 4.1 | 5.5 |
| Southwest | 8,310 | 3.8 | 4.6 | 1,935 | 4.1 | 5.6 |
| West | 5,411 | 4.0 | 4.3 | 1,091 | 4.1 | 5.2 |
| Central | 7,038 | 2.4 | 4.1 | 1,562 | 2.6 | 4.9 |
| Enlistment region | ||||||
| Southeast | 12,047 | 3.1 | 3.7 | 3,201 | 4.4 | 5.9 |
| Midwest | 28,504 | 3.6 | 4.6 | 7,189 | 3.9 | 4.8 |
| Southwest | 15,072 | 3.8 | 5.3 | 3,781 | 4.1 | 6.9 |
| West | 3,804 | 2.8 | 3.9 | 706 | 5.4 | 7.4 |
| Quarter of enlistment year | ||||||
| January–March | 15,050 | 3.8 | 4.5 | 3,775 | 4.1 | 6.0 |
| April–June | 14,810 | 3.0 | 4.3 | 3,741 | 3.7 | 5.7 |
| July–September | 18,450 | 3.9 | 5.0 | 4,534 | 4.3 | 5.7 |
| October–December | 12,010 | 3.2 | 4.7 | 3,031 | 4.1 | 5.2 |
IQR: 25–75 percentile.
Column variables do not sum to 100% due to missing information.
p-values <0.05 by Wilcoxon rank sum test for all variables comparing length of service by SCT status.
The adjusted OR for more than 5 yr compared with less than or equal to 5 yr of service for SCT-positive compared with SCT-negative was 1.37 (95% CI 1.31–1.43) (Table IV). SCT-positive females, non-Hispanic Blacks, ever (1 and 2+) deployed, Navy and Air Force compared with Army, and occupations (communications and intelligence, and health care) compared with repair/engineer occupations were more likely to stay in service longer than 5 yr compared with SCT-negative subjects. In contrast, SCT-positive subjects aged 20- to 29-yr olds compared with 18- to 19-yr olds at enlistment, quarter of enlistment other than from July to September, occupations (combat, armor/motor, and other) compared with repair/engineer occupations, and home regions (north, west, and central) as well as enlistment regions (midwest and southwest) compared with the southeast, were less likely to stay longer than 5 yr in service compared with SCT-negative subjects.
Table IV.
Association Between Length of Service (>5 yr Versus ≤5 yr) and SCT-Negative (−) Versus Positive (+) Status
| Adjusted ORa (95% CI) | |
|---|---|
| SCT | |
| Negative | Reference |
| Positive | 1.37 (1.31–1.43) |
| Gender | |
| Male | Reference |
| Female | 1.28 (1.22–1.33) |
| Age (yr) | |
| 18–19 | Reference |
| 20–24 | 0.87 (0.84–0.91) |
| 25–29 | 0.87 (0.81–0.94) |
| 30+ | 0.91 (0.80–1.04) |
| Race | |
| Non-Hispanic White | Reference |
| Non-Hispanic Black | 1.13 (1.03–1.24) |
| Hispanic | 1.06 (0.95–1.18) |
| Non-Hispanic others | 1.03 (0.91–1.16) |
| Number of deployment | |
| 0 | Reference |
| 1 | 5.45 (5.22–5.69) |
| 2+ | 18.86 (17.87–19.91) |
| Quarter year of enlistment | |
| July–September | Reference |
| January–March | 0.87 (0.83–0.92) |
| April–June | 0.72 (0.68–0.75) |
| October–December | 0.88 (0.83–0.93) |
| Service | |
| Army | Reference |
| Navy | 3.65 (3.08–4.34) |
| Air Force | 3.43 (3.01–3.91) |
| Marine | 0.93 (0.85–1.02) |
| Occupationa | |
| Repair/engineer | Reference |
| Combat | 0.68 (0.62–0.75) |
| Armor/motor/transport | 0.44 (0.40–0.48) |
| Communications/intelligence | 1.27 (1.21–1.34) |
| Health care | 2.10 (1.96–2.25) |
| Others | 0.54 (0.51–0.56) |
| Home district | |
| Southeast | Reference |
| North | 0.88 (0.83–0.93) |
| Southwest | 0.97 (0.92–1.03) |
| Northeast | 1.05 (0.98–1.12) |
| Mid-Atlantic | 0.97 (0.91–1.04) |
| West | 0.71 (0.66–0.76) |
| Central | 0.90 (0.84–0.97) |
| Enlistment district | |
| Southeast | Reference |
| Midwest | 0.53 (0.45–0.63) |
| Southwest | 0.85 (0.75–0.97) |
| West | 1.15 (1.05–1.25) |
aAdjusted OR are adjusted for all of the above variables.
Moreover, the crude mortality ratio by SCT status was 1.27 (95% CI 0.94–1.71). Cause of death by diagnostic categories and SCT status is shown in Figure 2. The proportion of cause-of-death diagnostic category was similar in SCT-positive versus SCT-negative fatalities except for suicide and self-directed violence and other causes (which includes hemolytic anemias, cancer, asthma, and pneumonia), which were more frequent in SCT-positive fatalities.
Figure 2.
Distribution of causes of death by SCT-positive and SCT-negative status. Other includes hemolytic anemias, cancer, asthma, and pneumonia.
Conclusion
This is the first military population-based, longitudinal, retrospective cohort study of the association of SCT status with deployment, length of service, and mortality to our knowledge. We found that SCT-positive service members had more frequent and longer length of deployments, longer length of service, and no significant difference in crude mortality ratio.
Previous research has consistently found that medical disqualifications and waivers for enlistment are associated with, in general, increased risk of first tour of duty (i.e., 3–5 yr of service) attrition.18,19 Our findings are not consistent with this previous literature and may be explained by the fact that SCT is a congenital condition and chronic health effects may not manifest during the young adult ages common in military service. In addition, young adults with SCT may have a higher propensity to enlist and remain in military service to access health care and career progression. AMSARA also found that enlistment medical waivers were not positively associated with length of deployment.20 Unpublished data by our group on this same cohort found an association between exertional heat illnesses (approximately 95% were either mild or heat exhaustion and less than 5% were heat stroke) and SCT status where approximately 40% of these illnesses could be attributed to SCT.
Strengths of the current study design include a large sample size, an open cohort with longitudinal follow-up for military and medical outcomes, and minimal loss to follow-up during military service. Our findings may be generalizable to other nation’s military forces that are similar in demographic characteristics, accession standards, and military service requirements. Limitations to the study include the potential for misclassification of SCT status due to false negatives, which would likely bias our results toward the null (no association). The small number of fatalities limited our ability to detect a crude association with SCT status or to perform multivariate analyses. Finally, the uniquely military enlistment and service requirements limit the generalizability of our length of service and mortality findings to other physically demanding populations such as law enforcement, fire fighters, and competitive athletes (e.g., National Collegiate Athletic Association and professional).
Future or ongoing research with this cohort includes the study of a variety of chronic medical conditions: thromboembolic disease, pregnancy-related hypertensive diseases, diabetes, and renal and pulmonary diseases. A cost-effectiveness analysis comparing universal with selective SCT screening on enlistment is needed to consider and balance the multiple positive and negative outcome associations with SCT status. Overall, this study found no evidence to support a more restrictive SCT enlistment standard or universal screening to reduce military and individual relevant outcomes.
SCT-positive compared with SCT-negative service members experienced more frequent and longer deployments, longer length of military service, and no significant difference in crude mortality. Future research on relatively rare SCT-associated chronic medical conditions in young adults such as thromboembolic and chronic kidney diseases and a cost-effectiveness analysis of SCT screening practices are needed to inform evidence-based SCT enlistment policies.
Acknowledgments
The authors thank Lee Hurt DrPH, MPH, of the Armed Forces Health Surveillance Branch and Gosia Nowak MSc, MPH, of the Navy and Marine Corps Public Health Center for creation of the study analytic dataset. The study was funded by an Interagency Agreement with the National Heart, Lung, and Blood Institute/NIH. Data from the Defense Medical Surveillance System, The Armed Forces Health Surveillance Branch, U.S. Department of Defense, Silver Spring, Maryland; data period 1992–2012; data released October 27, 2014.
Funding
Sponsoring Organization: Blood Epidemiology and Clinical Therapeutics Branch, Division of Blood Diseases and Resources, National Heart, Lung and Blood Institute, NIH
Agreement #: NHLBI, Interagency Agreement (A-HL-14-001-001-00000) USUHS Grant #: HU0001-14-0019
Date(s): FY14–17
Conflicts of Interest
The authors declare that they have no conflicts of interest.
References
- 1. Yusuf HR, Lloyd-Puryear MA, Grant AM, Parker CS, Creary MS, Atrash HK: Sickle cell disease: the need for a public health agenda. Am J Prev Med 2011; 41(6 Suppl 4): S376–83. [DOI] [PubMed] [Google Scholar]
- 2. Centers for Disease Control and Prevention : Sickle Cell Disease. Available at http://www.cdc.gov/ncbddd/sicklecell/treatments.html; accessed May 18, 2017.
- 3. Dupervil B, Grosse S, Burnett A, Parker C: Emergency department visits and inpatient admissions associated with priapism among males with sickle cell disease in the United States, 2006–2010. PLoS One 2016; 11(4): e0153257 Available at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153257; accessed May 18, 2017. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4. Sobota AE, Umeh E, Mack JW: Young adult perspectives on a successful transition from pediatric to adult care in sickle cell disease. J Hematol Res 2015; 2(1): 17–24. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5. Grant AM, Parker CS, Jordan LB, et al. : Public health implications of sickle cell trait: a report of the CDC meeting. Am J Prev Med 2011; 41(6 Suppl 4): S435–9. [DOI] [PubMed] [Google Scholar]
- 6. Heller P, Best WR, Nelson RB, Becktel J: Clinical implications of sickle-cell trait and glucose-6-phosphate dehydrogenase deficiency in hospitalized black male patients. N Engl J Med 1979; 300(18): 1001–5. [DOI] [PubMed] [Google Scholar]
- 7. Niebuhr DW, Chen L, Shao S, Goldsmith J, Byrne C, Singer DE: Sickle cell trait prevalence among U.S. Military service members: 1992–2012. Mil Med 2017; 182(3): e1819–24. [DOI] [PubMed] [Google Scholar]
- 8. Hosek J, Kavanagh J, Miller L: How Deployments Affect Service Members. RAND Corporation 2006. Available at http://www.rand.org/content/dam/rand/pubs/monographs/2005/RAND_MG432.pdf; accessed May 18, 2017.
- 9. Department of Defense : DoD Announces Recruiting, Retention Numbers Through June 2015. Available at https://www.defense.gov/News/Article/Article/612742/dod-announces-recruiting-retention-numbers-through-june-2015; accessed May 18, 2017.
- 10. Department of Defense : Instruction Number 6130.03 (updated Sep 13, 2011). Available at http://www.dtic.mil/whs/directives/corres/pdf/613003p.pdf; Accessed May 18, 2017.
- 11. United States Army : Army Regulation 601-280, Army Retention Program (updated Apr 1, 2016). Available at http://www.apd.army.mil/epubs/DR_pubs/DR_a/pdf/web/r601_280.pdf; accessed May 18, 2017.
- 12. United States Army : Army Regulation 40–501, Standards of Medical Fitness (Revised Apr 11, 2011). Available at http://www.apd.army.mil/pdffiles/r40_501.pdf; accessed Mar 30, 2017.
- 13. United States Army : Army Regulation 635–40, Disability Evaluation for Retention, Retirement or Separation (updated Jan 19, 2017). Available at http://www.apd.army.mil/epubs/DR_pubs/DR_a/pdf/web/AR635-40_Web_FINAL.pdf; accessed May 18, 2017.
- 14. United States Air Force : AFI 48-123, Medical Examinations and Standards (updated Sep 19, 2016). Available at http://static.e-publishing.af.mil/production/1/af_sg/publication/afi48-123/afi48-123.pdf; accessed May 18, 2017.
- 15. United States Navy : Manual of the Medical Department (MANMED), NAVMED P-117, Chapter 15, Medical Examinations (updated Feb 3, 2017). Available at http://www.med.navy.mil/directives/Documents/NAVMED P-117 %28MANMED%29/Chapter 15 Medical Examinations %28incorporates Changes 126 128 135–140 144 145 147 150–152 154–156,159 and 160 below%29.pdf; accessed May 18, 2017.
- 16. Tsaras G, Owusu-Ansah A, Boateng FO, Amoateng-Adjepong Y: Complications associated with sickle cell trait: a brief narrative review. Am J Med 2009; 122(6): 507–12. [DOI] [PubMed] [Google Scholar]
- 17. Webber BJ, Witkop CT: Screening for sickle-cell trait at accession to the United States military. Mil Med 2014; 179(11): 1184–9. [DOI] [PubMed] [Google Scholar]
- 18. Gubata ME, Boivin MR, Cowan DN, et al. Accession Medical Standards Analysis & Research Activity (AMSARA) 2013 Annual Report. Walter Reed Army Institute of Research, Silver Spring, MD. Available at http://www.dtic.mil/dtic/tr/fulltext/u2/a580689.pdf; accessed May 18, 2017.
- 19. Niebuhr DW, Powers TE, Li Y, Millikan AM: Chapter 4: Morbidity and attrition related to medical conditions in recruit In: Textbooks of Military Medicine, Recruit Medicine. Edited by DeKoning BL.Washington, D.C., Borden Institute, 2006. Available at https://ke.army.mil/bordeninstitute/published_volumes/recruit_medicine/RM-ch04.pdf. accessed May 18, 2017. [Google Scholar]
- 20. Gubata ME, Oetting AA, Niebuhr DW, Cowan DN: Accession medical waivers and deployment duration in the U.S. Army. Mil Med 2013; 178(6): 625–30. [DOI] [PubMed] [Google Scholar]