Army Begins Screening Recruits for Sickle Cell Trait, Joining Other Services

Military Has Long History of Grappling with Sickle Cell Conditions

The Army began testing recruits for sickle cell trait (SCT) late last year and is expected to implement universal screening this year. Similar programs already existed in other military services and generally were put into place after medical emergencies or even deaths of servicemembers with SCT. What is interesting about the new Army program is that the primary impetus isn’t to exclude or punish recruits who test positive but to educate them about that condition and risks of passing on more-serious sickle cell anemia to their children.

FORT EUSTIS, VA — Late last year, the Army first began testing recruits for sickle cell trait (SCT) to identify at-risk soldiers, with plans to implement universal screening by later this year, according to the U.S. Army Training and Doctrine Command medical officer.

Maj. Sean Donohue, command surgeon at TRADOC’s Center for Initial Military Training, said in an Army press release that the screening is part of a larger initiative to educate both Army leaders and soldiers on how to deal with the lifelong medical condition.

The Navy, including the Marines, and the Air Force already had been doing some level of SCT screening. In fact, military services have been grappling with the risks of sickle cell disease (SCD) for more than 50 years.

According to the national Centers for Disease Control and Prevention, SCD is a group of inherited red blood cell disorders. In SCD patients, red blood cells become hard and sticky and look like a C-shaped farm tool called a “sickle.” Because sickle cells die early, patients have a constant shortage of red blood cells. In addition, the cells travel through small blood vessels, get stuck and clog blood flow which can cause pain and other serious problems such infection, acute chest syndrome and stroke.

SCT occurs when one sickle cell gene (“S”) from one parent and one normal gene (“A”) from the other parent and is inherited. “People with SCT usually do not have any of the signs of the disease and live a normal life, but they can pass the trait on to their children,” according to the CDC. “Additionally, there are a few, uncommon health problems that may potentially be related to sickle cell trait.”

In 1968, four Marine recruits with SCT died during training exercises at elevation, leading Navy Medicine to begin testing all recruits and limiting the operational billets available to those who tested positive. In 1981, however, a class action lawsuit was filed against the Air Force Academy, citing racial discrimination by declining to admit students with SCT, which is predominantly found in African Americans. In response, DoD mandated that restrictions be removed.

Now, all Marine recruits have a battery of blood testing done on day three of training by staff at Branch Health Clinic MCRD Parris Island, SC. Results are sent to the Medical Dispositions Officer for review. The Navy pointed out that, if a recruit shows more than 45% hemoglobin S, a recruit can be separated from training for a condition that is disqualifying but is not a disability. All separated recruits receive specific counseling on the condition in addition to genetic counseling. While recruits at less than 45% are also counseled, they are allowed to return to training.

The screening remains controversial, however, with several studies questioning whether it even is necessary. A 2018 article published in Military Medicine pointed out that SCT affects an estimated 5.02% of non-Hispanic blacks, 1.08% of Hispanics, and 0.1% of whites in the U.S. military.¹

Researchers from the Uniformed Services of the Health Sciences and Walter Reed National Military Medical Center conducted a retrospective cohort study of 15,081 SCT-positive vs.60,320 SCT-negative U.S. active duty personnel enlisted from 1992 to 2012 and followed through 2013. They determined that SCT-positive servicemembers deployed more frequently, for greater lengths of time, and remained in service longer. Yet, according to the authors, “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.”

An earlier, 2016, study led by Stanford University looked at 47,944 Black soldiers who had undergone testing for SCT who were on active duty in the U.S. Army between January 2011 and December 2014. Results published in the New England Journal of Medicine found that SCT was not associated with a higher risk of death than absence of the trait, although it was associated with a significantly higher risk of exertional rhabdomyolysis.²

Senior author Lianne Kurina, PhD, of Stanford noted at the time that it had been assumed that SCT increased the risk of death, of exertional rhabdomyolysis and of heat stroke. Yet, she said the risk of exertional rhabdomyolysis was found to be only 54% higher among African American soldiers with SCT than among those without it. While that might sound like a lot, Kurina pointed out that some common prescription drugs confer a 300% increase and that smoking, obesity and increasing age also increase the risk around 50%.

The improved statistics might be related to better management by the military, with the requirement of better hydration, gradual movement up to strenuous exercise and allowances for extreme heat, she suggested.

“The most important thing to come out of this study is the really reassuring news that, under conditions of universal precautions against dehydration and overheating, we don’t see an elevation in the risk of mortality in people with sickle cell trait,” Kurina said, stating that the results call into question the need to screen servicemembers with SCT, especially with better safety precautions during intense exertion.

Renal Disorders

A 2019 study from some of the same Stanford authors noted that SCT and certain renal disorders are “disproportionately prevalent among African American individuals, so a clear understanding of their association is important.”

The team conducted a longitudinal study using the Stanford Military Data Repository to examine SCT in relation to the incidence of acute kidney injury (AKI) and chronic kidney disease (CKD), focusing on African American U.S. Army soldiers on active duty between January 2011 and December 2014.

Reporting in the British Journal of Haematology, they found that the cumulative incidence was 0.51% for AKI (236 cases out of 45,901 soldiers) and 0.56% for CKD (255 cases out of 45,882 soldiers). Analysis determined that SCT was associated with significantly higher adjusted odds of both AKI [odds ratio (OR): 1.74; 95% confidence interval (CI): 1.17-2.59] and CKD (OR: 2.0; 95% CI: 1.39-2.88).³

The same year the study came out, an autopsy found that SCT was a contributing factor in the death of an Eglin Air Force Base captain after a fitness test in August 2019. An investigation released by the Air Force came to that conclusion after the death of Capt. Tranay Tanner, 29.

Tanner had a known diagnosis of SCT, according to the report, but never had any previous medical complications related to it.

In 2011, a summit on SCT introduced the term exercise collapse associated with SCT (ECAST). Then, according to a 2021 article in Current Sports Medicine Reports, a series of ECAST deaths in military personnel in 2019 spurred reevaluation of current efforts and led to a second summit in October 2019 hosted by the Consortium for Health and Military Performance of the Uniformed Services University in Bethesda, MD. After that, the Army added SCT to the blood panels.⁴

In the first month the Army began routine testing in 2020, about 2% of recruits were diagnosed with the blood disorder, similar to the national average.

“On the enlisted side, recruits [at basic combat training] are now tested as part of their initial screening exam,” Donohue said. The SCT tests are grouped in “with a variety of other blood samples as part of initial processing.”

He added that the goal isn’t to keep those testing positive from military service or any occupational specialty but to ensure soldiers have the care and support they need.

Recruits found to carry SCT meet with a healthcare provider and then receive additional counseling and education.

As for benefits to the Army, Donohue said knowing recruits’ SCT status helps better distinguish “the difference between someone who may look like they have a heat-related injury from someone who has [SCT].”

“We’ve been doing this at our Drill Sergeant Academy, in particular, and educating them on what exertional collapse related to sickle cell looks like,” he added.

1. Singer DE, Chen L, Shao S, Goldsmith J, Byrne C, Niebuhr DW. The Association Between Sickle Cell Trait in U.S. Service Members with Deployment, Length of Service, and Mortality, 1992-2012. Mil Med. 2018 Mar 1;183(3-4):e213-e218. doi: 10.1093/milmed/usx037. PMID: 29514337; PMCID: PMC6544874.
2. Nelson DA, Deuster PA, Carter R 3rd, Hill OT, Wolcott VL, Kurina LM. Sickle Cell Trait, Rhabdomyolysis, and Mortality among U.S. Army Soldiers. N Engl J Med. 2016 Aug 4;375(5):435-42. doi: 10.1056/NEJMoa1516257. PMID: 27518662; PMCID: PMC5026312.
3. Hu J, Nelson DA, Deuster PA, Marks ES, O’Connor FG, Kurina LM. Sickle cell trait and renal disease among African American U.S. Army soldiers. Br J Haematol. 2019 May;185(3):532-540. doi: 10.1111/bjh.15820. Epub 2019 Mar 11. PMID: 30859563; PMCID: PMC6470032.
4. O’Connor FG, Franzos MA, Nye NS, Nelson DA, Shell D, Voss JD, Anderson SA, Coleman NJ, Thompson AA, Harmon KG, Deuster PA. Summit on Exercise Collapse Associated with Sickle Cell Trait: Finding the “Way Ahead”. Curr Sports Med Rep. 2021 Jan 1;20(1):47-56. doi: 10.1249/JSR.0000000000000801. PMID: 33395130.