Sickle cell considerations in athletes

Sickle Cell Trait and Adverse Pregnancy Outcomes: Is There a Link?

Objective

The objective is to assess the overall prevalence of maternal and neonatal pregnancy-related complications, and to compare their frequency among women with sickle cell trait (SCT) and those with normal hemoglobin patterns to examine the association between SCT and maternal and neonatal outcomes.

Methods

A retrospective cross-sectional case-control study was conducted by reviewing medical data from the labor room registry book and electronic database. All pregnant ladies delivered in Salmaneya medical complex from January 1 to December 31, 2019 were included. Patients were divided into two groups based on the presence or absence of SCT. Adverse maternal and neonatal outcomes were compared between the two groups. 

Results

Out of the 5,067 pregnant women reviewed, 934 (18.4%) were included (460 (49.3%) with SCT and 474 (50.7%) with healthy controls). Overall, maternal, and neonatal complications were noted in 40.8% (n=381) and 16.3% (n=152), respectively. In univariate analysis, patients with SCT were significantly more likely to underwent cesarean sections compared to healthy women, 28.7% (n=132) vs. 21.7% (n=103), respectively (P=0.044) and to have more intrauterine fetal death (3% [n=14] vs. 0.2% [n=1], respectively (P<0.0001). No significant differences were found between the two groups in terms of the occurrence of the pregnancy-related hypertensive disorder, gestational diabetes, small for gestational age, and preterm delivery. 

Conclusion

The result of this large, retrospective cross-sectional, case-control study shows that pregnant women with SCT were associated with an increase in intrauterine fetal death in comparison with pregnant women with normal hemoglobin. There were no differences found in pregnancy-related hypertensive disorder, gestational diabetes, small for gestational age, and preterm delivery. This result will emphasize the requirement of additional studies to scrutinize these findings and to determine whether there may be a benefit of a unique antenatal surveillance guideline for such patients.

Sudden Death in High School Athletes: A Case Series Examining the Influence of Sickle Cell Trait

ABSTRACT

Athletes with sickle cell trait (SCT) have up to a 37-fold increased risk of exercise-related death. Exertional collapse associated with sickle cell trait (ECAST) is uncommon but can lead to exercise-related death due to exertional sickling. We present a case series of fatal ECAST in high school athletes aged 14 to 16 years. All 3 athletes experienced collapse during practice sessions with muscle pain or weakness. Upon evaluation at the hospital, the athletes had a significant metabolic acidosis that did not respond as expected to fluid resuscitation. Admitting diagnoses for the athletes included exertional heat stroke or dehydration. All 3 athletes had profound rhabdomyolysis leading to acute renal failure, worsening metabolic acidosis, and hyperkalemia. They rapidly progressed to disseminated intravascular coagulation, multiorgan system failure, and death. The autopsies of all 3 athletes showed extensive sickle cell vaso-occlusion involving the spleen liver, and muscles. Final clinical and pathologic diagnosis supported ECAST with fatal exertional rhabdomyolysis. Exertional collapse associated with sickle cell trait is an uncommon but potentially deadly condition that is often underrecognized or misdiagnosed as exertional heat stroke. The development of ECAST is thought to be multifactorial with exercise intensity, recent illness, and exercising conditions (ie, heat and altitude). Prevention should be the primary goal for athletes with SCT through exercise modification, education of precipitation factors, and cessation of exercise with recent illness. Athletes with suspected ECAST should undergo aggressive resuscitation with a low threshold for early transfer to a tertiary care facility for further management and potential hemodialysis.

Screening by Self-Report Underestimates Sickle Cell Trait in High-School Athletes

Background: Sickle cell trait (SCT) has received attention as a cause of death in college athletes, leading to mandatory lab SCT screening in National Collegiate Athletic Association (NCAA) athletes. High-school athletes are commonly screened by self-report. There are no known studies for evaluating whether this method is effective as a screening tool.

Hypothesis: The local prevalence rate of SCT as self-reported on the preparticipation evaluation (PPE) forms would be lower than the national accepted average.

Methods: PPE forms from the Department of Orthopedics and Rehabilitation of the University of Florida (UF) were reviewed between January 1, 2017, and April 30, 2018. The Florida High School PPE form includes a yes/no question to assess the diagnosis of SCT. The prevalence established by self-report was then compared with the national prevalence for SCT in the comparable race/ethnicity groups reported by the CDC. The response rate of SCT questions was also compared to other common cardiac screening questions.

Results: A total of 401 forms were reviewed. Six (1.5%) students answered “yes,” 351 answered “no,” and 44 left the SCT question blank. All six athletes who self-reported “yes” were Black and made up 3.7% of the 162 known Black respondents. This self-report rate for Black/African Americans was well below the expected 7.3% described by the CDC. Response rates were also lower than the comparable cardiac screening questions.

Conclusions: Self-report SCT status rates are lower than the accepted prevalence in a similar population. Significant inconsistencies in reporting were also determined.

Clinical relevance: This is a rare study to evaluate the self-reported prevalence of SCT in high-school athletes. Below average reporting of SCT and inconsistency in completion of the forms increase the concern for accuracy and effectiveness of current high-school SCT screening methods relying on self-report.

Atypical Presentations of Exertional Collapse

ABSTRACT

Exertional collapse associated with sickle trait (ECAST) is an underrecognized cause of exertional collapse triggered by complex mechanisms involving acidosis, rhabdomyolysis, and arrhythmias, all of which create sickling, vaso-occlusive problems, and ultimately end organ failure. Three cases are described in young athletes, as well as 12 other examples of ECAST noted in case reports and news sources. Exertional collapse associated with sickle trait can be differentiated from other common causes of collapse (exertional heat syndrome, acute cardiac events, and asthma) because it is a conscious collapse without neurological changes, occurs early in workout with only mildly elevated body temperature, and involves muscle pain and weakness but not cramping. Aggressive early management and transport to care facilities can reverse ECAST in certain cases. This article discusses tips for early recognition, initial treatment in the emergency department, and precautions that can be taken to prevent sickling collapse in athletes with sickle cell trait (SCT).

Thrombosis associated with mycoplasma pneumoniae infection (Review)

Mycoplasma pneumoniae is a common pathogen causing respiratory infections in children and adults. In addition to respiratory diseases, Mycoplasma pneumoniae is also involved in numerous extrapulmonary diseases. Thrombosis is an extrapulmonary manifestation associated with Mycoplasma pneumoniae infection. In recent years, an increasing number of case reports have been published identifying thrombosis secondary to Mycoplasma pneumoniae infection. In the present study, the available relevant literature in English available on PubMed, Medline and Web of Science was consulted. The results of the present study demonstrated that in patients with thrombosis caused by Mycoplasma pneumoniae infection, some of the factors causing thrombosis are transient and some are due to hereditary thrombophilia. Following timely treatment, the majority of patients recovered completely but some patients had a poor prognosis. The present review focuses on the pathogenesis, clinical features, treatment and prognosis of this crucial issue, which contributes toward the understanding of the disease.

NCAA Division I American football players with sickle cell trait have altered hematological responses and hydration status

Sickle cell trait (SCT) is a risk factor of collapse and sudden death in athletes. We conducted a longitudinal study to determine the hematological responses and hydration status in NCAA Division I American football players with SCT. The study took place over 2 years with 6 SCT and 6 position-matched controls (CON) in year 1; and 4 SCT and 4 CON in year 2. In year 2, three of the four SCT players were recruited and re-enrolled with new position-matched controls (total sample data = 10 SCT and 10 CON). Blood samples were taken at three visits: pre-camp, post-camp, and post-season to examine hemoglobin variants, complete blood counts, and chemistry panel 26. Hydration status was assessed by measuring body weight change, urine specific gravity, and urine and sweat electrolyte concentrations during the pre-season training camp. All SCT players were confirmed to have SCT (HbS = 37.9 ± 2.4%) and had greater red cell distribution width (RDW) compared to CON across all visits. Serum uric acid was higher in SCT (7.3 ± 1.0 mg/dL) compared to CON (6.1 ± 0.6 mg/dL; p = 0.001). Furthermore, serum creatine kinase levels were greater in SCT (1617.0 ± 1034.8 IU/L) at pre-camp compared to CON (1037.4 ± 602.8 IU/L; p = 0.03). SCT players exhibited lower pre- and post-practice urine electrolytes and urine specific gravity (SCT pre: 1.019 ± 0.005 vs. CON pre: 1.026 ± 0.008 p < 0.001; SCT post: 1.020 ± 0.005 vs. CON post: 1.030 ± 0.008 p < 0.01), whereas sweat sodium concentrations were higher in SCT players (55.4 ± 13.6 mmol/L) compared to CON (45.5 ± 10.6 mmol/L; p < 0.001). Given the evidence, greater uric acid and CPK levels in SCT players compared to CON may be an early indicator of altered kidney function and muscle damage, which could be added into NCAA guidelines for surveillance among SCT players. Consistent education and reinforcement of the importance of adequate fluid balance during exercise are critical for both SCT and CON players.

Summit on Exercise Collapse Associated with Sickle Cell Trait: Finding the "Way Ahead"

ABSTRACT

Although largely benign, sickle cell trait (SCT) has been associated with exertion-related events, to include sudden death. In 2011, a summit on SCT introduced the term exercise collapse associated with SCT (ECAST). A series of ECAST deaths in military personnel in 2019 prompted 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. The goals were to (1) review current service policies on SCT screening, (2) develop draft procedural instructions for executing current policy on SCT within the Department of Defense, (3) develop draft clinical practice guidelines for management of ECAST, (4) establish a framework for education on SCT and ECAST, and (5) prepare a research agenda to address identified gaps.

The prevalence of sickle cell trait in Division I university athletics programs

Objectives: To determine the prevalence of student-athletes with sickle cell trait (SCT) and describe their demographics, prior knowledge of status, and hemoglobin (Hb) profile. Methods: A retrospective chart review was conducted at two National Collegiate Athletic Association Division I universities. Participants were student-athletes during the 2010/11-2018/19 academic years. The independent variable was SCT status. Main outcome measures included actual prevalence of SCT positive student-athletes, sex, race, sport, prior knowledge of personal and family history SCT status, and Hb profile (HbA, HbA2, HbS, HbF, HbC) proportions. Results: Fifty-three SCT positive student-athletes (13.2 ± 2.0 per academic year) were identified, accounting for ~1% of the student-athlete population annually. The majority were Black/African-American (n = 49, 100.0%; 4 missing) and males (n = 44, 83.0%). Football had the majority (n = 28, 52.8%) of SCT student-athletes. Most student-athletes were unaware of their SCT status (n = 33, 62.3%). There was no difference between actual and expected prevalence of SCT student-athletes overall and by race in any academic year (p > 0.05). Results of Hb electrophoresis testing were available for 44 (83.0%) student-athletes. Average values for HbA, HbA2, HbS, HbF and HbC were 58.54 ± 4.26%, 3.42 ± 0.53%, 37.99 ± 4.60%, 0.17 ± 0.68% and 0.00 ± 0.00%, respectively. Conclusions: Student-athletes with SCT were a small proportion of the student-athlete population. The majority of SCT student-athletes had no prior knowledge of personal or family history; therefore, it is insufficient to rely on self-reported history. No difference was found between actual and expected prevalence of SCT student-athletes. Due to high proportion of student-athletes who are unaware of their SCT status, institutions should facilitate SCT screening with confirmatory testing for all student-athletes to prevent missed identification of those with SCT.

Sudden Death Associated With Sickle Cell Trait Before and After Mandatory Screening

BACKGROUND

Sickle cell trait (SCT) has been associated with an increased risk of sudden death in athletes during strenuous exercise. In August 2010, the National Collegiate Athletic Association (NCAA) began requiring athletes to be screened for SCT, provide proof of SCT status, or sign a waiver and launched an educational campaign for athletes, coaches, and medical staff. The impact of this program is unknown. The purpose of this study was to determine the incidence of death associated with sickle cell trait (daSCT) in NCAA athletes before and after legislation.

HYPOTHESIS

NCAA SCT legislation will decrease the incidence of daSCT.

STUDY DESIGN

Observational study.

LEVEL OF EVIDENCE

Level 2.

METHODS

A database of NCAA athlete deaths from 2000 to 2019 was reviewed for daSCT. A total of 8,309,050 athlete-years (AY) were included. Incidence of death was calculated before and after legislation.

RESULTS

The incidence of daSCT in Division I (DI) football athletes before legislation (n = 9) was 1:28,145 AY and after legislation (n = 1) was 1:250,468 AY (relative risk [RR], 0.112; 95% CI, 0.003-0.811; P = 0.022), an 89% reduction in risk after legislation was enacted. The incidence of daSCT in African American DI football athletes before legislation (n = 9) was 1:12,519 AY and after legislation (n = 1) was 1:118,464 AY (RR, 0.106; 95% CI, 0.002-0.763; P = 0.017), also an 89% risk reduction after legislation was enacted. For all NCAA athletes, the incidence of daSCT was 1:489,749 AY before legislation (n = 10) and 1:1,705,780 AY after legislation (n = 2) (RR, 0.288; 95% CI, 0.031-1.347; P = 0.146).

CONCLUSION

The incidence of daSCT in DI football athletes has decreased significantly since legislation was enacted. Cases of daSCT outside of football are rare. It is unclear whether the decrease is related to screening for SCT, education, or both.

CLINICAL RELEVANCE

This is the first evidence that NCAA SCT legislation may save lives.

Adverse Pregnancy Outcomes in Women with Sickle Cell Trait

Objective  To compare adverse pregnancy outcomes between women with sickle cell trait (SCT) and women with normal hemoglobin. Study Design  A retrospective cohort study of women who delivered within Kaiser Permanente Northern California between 2006 and 2013. Using hemoglobin electrophoretic profiles, we defined women with hemoglobin AS (HbAS) as having SCT and those with hemoglobin AA (HbAA) as having normal hemoglobin. Outcomes were pregnancy-induced hypertension (PIH), small for gestational age (SGA), gestational diabetes (GDM), and preterm delivery (PTD). Demographic and pregnancy outcome variations were assessed in bivariate analyses. Multivariable logistic regression modeling was used to estimate odds ratios for the association between primary outcomes and selected characteristics. Results  Of 31,840 eligible women, 868 (2.7%) had SCT. Women with SCT were more likely to have PIH (15.6% vs. 12.2%, p value = 0.003) and SGA (8.3% vs. 6.1%, p value = 0.008), less likely to have GDM (6.8% vs. 9.8%, p value = 0.003) and had similar PTD prevalence (8.1% vs. 7.6%, p value = 0.600). In multivariable analyses, SCT was not an independent predictor of these outcomes. Racial/ethnic minorities had higher adjusted odds of PIH, SGA, and GDM. Conclusion  SCT alone does not appear to be associated with adverse pregnancy outcomes. Race/ethnicity is a risk factor for adverse pregnancy outcomes.

Marathons and myasthenia gravis: a case report

Background

The cardinal symptoms of auto-immune myasthenia gravis are fatigue and weakness. Endurance events such as marathon running would seem incompatible with this chronic disease. Many patients stop sport altogether. There is limited literature of patients with auto-immune myasthenia gravis undergoing regular endurance exercise.

Case presentation

We report the case of a 36-year-old female who began long-distance running whilst experiencing initial symptoms of myasthenia gravis. She was diagnosed with auto-immune myasthenia gravis and whilst advised to stop all sport, her way of fighting and living with this chronic and unpredictable disease was to continue running to maintain a healthy body and mind. Despite suffering from ocular, bulbar and localized limb fatigability, she managed to complete multiple marathons and achieve disease stability with cholinesterase inhibitors.

Conclusions

Marathon and half-marathon running lead to distinct changes in mediators of inflammation in an exercise-dose-dependent manner. Despite symptoms of weakness and fatigue in certain muscles in myasthenia gravis, physical exertion remains possible and may not worsen symptoms as demonstrated in this case and recent studies. The immunomodulatory role of exercise could be considered in this case however this hypothesis remains to be confirmed in future studies with quantitative data.

Twelve cases of exertional rhabdomyolysis in college football players from the same institution over a 23-year span: a descriptive study

BACKGROUND

Rhabdomyolysis is a syndrome characterized by muscle necrosis that leads to release of the intracellular contents of muscle cells into the systemic circulation. Rhabdomyolysis due to overexertion is an uncommon but well-known severe complication of strenuous activity. Exertional rhabdomyolysis (ER) is typically described in weight lifters and military recruits undergoing basic training. Few cases have been reported in football players without known predisposing risk factors. We report our experience with this condition in college football players in a single institution.

MATERIALS AND METHODS

College football players hospitalized for heat illness complicated by rhabdomyolysis were identified over a 23-year period. Clinical and laboratory findings were collected. Clinical course was recorded.

RESULTS

Twelve patients were identified. All were Black males. One had sickle cell trait. BMI averaged 33 kg/m² (range 23-45 kg/m²). Peak creatine phosphokinase (CPK) averaged 14,850 IU/L (range 1,021-109,616 IU/L). Serum creatinine averaged 1.9 mg/dl (range 1.2-3.1 mg/dl). Ten of twelve cases occurred in August. All responded to intravenous hydration with normalization of CPK and renal function. All returned to football.

CONCLUSIONS

ER is a serious complication of strenuous physical activity that can threaten renal function. ER tends to occur in August, which coincides with the start of football practice when athletes are more likely to be detrained. The condition can occur in Black athletes in the absence of sickle cell trait. ER carries a good prognosis when recognized early and treated adequately.

Implementation of the NCAA Sickle Cell Trait Screening Policy: A Survey of Athletic Staff and Student-athletes

OBJECTIVE

To describe the perspectives and experiences of athletic trainers, coaches, and student-athletes approximately three years post-implementation of the NCAA sickle cell trait (SCT) screening policy.

PARTICIPANTS

Two-hundred and eight student-athletes, 32 athletic trainers, and 43 coaches from 10 NCAA Division I (DI) institutions in North Carolina from January to June 2014.

METHODS

Two online surveys were used to assess knowledge, perspectives, and experiences.

RESULTS

Athletic staff were more supportive than student-athletes of the need for the policy. Noted challenges included variation in implementation and follow-up for SCT-positive athletes, financial costs to institutions and athletes, and timing of the screening.

CONCLUSIONS

More education about SCT is needed for student-athletes and athletic staff in order to help make the implementation more successful. All parties need to be in agreement regarding the importance of knowing which student-athletes have SCT and how that information will be utilized.

Perspectives on Exertional Rhabdomyolysis

Exertional (exercise-induced) rhabdomyolysis is a potentially life threatening condition that has been the subject of research, intense discussion, and media attention. The causes of rhabdomyolysis are numerous and can include direct muscle injury, unaccustomed exercise, ischemia, extreme temperatures, electrolyte abnormalities, endocrinologic conditions, genetic disorders, autoimmune disorders, infections, drugs, toxins, and venoms. The objective of this article is to review the literature on exertional rhabdomyolysis, identify precipitating factors, and examine the role of the dietary supplement creatine monohydrate. PubMed and SPORTDiscus databases were searched using the terms rhabdomyolysis, muscle damage, creatine, creatine supplementation, creatine monohydrate, and phosphocreatine. Additionally, the references of papers identified through this search were examined for relevant studies. A meta-analysis was not performed. Although the prevalence of rhabdomyolysis is low, instances still occur where exercise is improperly prescribed or used as punishment, or incomplete medical history is taken, and exertional rhabdomyolysis occurs. Creatine monohydrate does not appear to be a precipitating factor for exertional rhabdomyolysis. Healthcare professionals should be able to recognize the basic signs of exertional rhabdomyolysis so prompt treatment can be administered. For the risk of rhabdomyolysis to remain low, exercise testing and prescription must be properly conducted based on professional standards.

Perspectives and Practices of Athletic Trainers and Team Physicians Implementing the 2010 NCAA Sickle Cell Trait Screening Policy

Sickle cell trait (SCT) is usually benign. However, there are some conditions that may lead to SCT-related problems and put athletes with the trait at particular risk. In 2010 the National Collegiate Athletic Association (NCAA) issued a policy that required all Division I (DI) student-athletes to confirm their SCT status or sign a liability waiver to opt out of testing. Athletic trainers and team physicians play key roles in the policy implementation and we examined their perceptions and practices. Between December 2013 and March 2014 we interviewed 13 head athletic trainers and team physicians at NCAA Division I colleges and universities in North Carolina. We used an interview guide with open-ended questions covering knowledge of SCT, historical screening and education practices, current implementation, and policy benefits and challenges. Participants were knowledgeable about SCT and thought the policy was beneficial in providing SCT health information to and for student-athletes. Schools varied in provision of genetic counseling, offering the waiver, SCT tests administered, and other aspects. Challenges included: insufficient guidance from the NCAA; financial considerations; and misunderstanding of the relationships of race and ancestry to SCT risk. Athletic staff found the policy valuable, but felt it needs clarity and standardization.

NCAA Football Off-Season Training: Unanswered Prayers… A Prayer Answered

Off-season training in year-round collegiate football is purported to be performance enhancing. Absent principles of exercise physiology, excesses in sport-training regimens pose risk to the participant athletes. Since 2000, 33 National Collegiate Athletic Association (NCAA) football players have died in sport: 27 nontraumatic deaths and 6 traumatic deaths, a ratio of 4.5 nontraumatic deaths for every traumatic death. On average, 2 NCAA football players die per season. Best practices, consensus guidelines, and precautions are ignored, elevating the risk. However, standards exist that will, if heeded, prevent nontraumatic death in athletes training for sport. Sickle cell trait status knowledge and tailored precautions are preventing deaths from exertional collapse associated with sickle cell trait. Adherence to established principles of exercise physiology and best-practice training standards, which is long overdue, will help to prevent not only deaths from exertional collapse associated with sickle cell trait but also sudden cardiac, exertional heat stroke, and asthma deaths.

Athletes at High Altitude

CONTEXT

Athletes at different skill levels perform strenuous physical activity at high altitude for a variety of reasons. Multiple team and endurance events are held at high altitude and may place athletes at increased risk for developing acute high altitude illness (AHAI). Training at high altitude has been a routine part of preparation for some of the high level athletes for a long time. There is a general belief that altitude training improves athletic performance for competitive and recreational athletes.

EVIDENCE ACQUISITION

A review of relevant publications between 1980 and 2015 was completed using PubMed and Google Scholar.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 3.

RESULTS

AHAI is a relatively uncommon and potentially serious condition among travelers to altitudes above 2500 m. The broad term AHAI includes several syndromes such as acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), and high altitude cerebral edema (HACE). Athletes may be at higher risk for developing AHAI due to faster ascent and more vigorous exertion compared with nonathletes. Evidence regarding the effects of altitude training on athletic performance is weak. The natural live high, train low altitude training strategy may provide the best protocol for enhancing endurance performance in elite and subelite athletes. High altitude sports are generally safe for recreational athletes, but they should be aware of their individual risks.

CONCLUSION

Individualized and appropriate acclimatization is an essential component of injury and illness prevention.

Acute Lumbar Paraspinal Myonecrosis in Football Players with Sickle Cell Trait: A Case Series

We report six cases of a novel syndrome of acute, exertional low back pain in football players, five in college and one in the National Football League. All six are African Americans with sickle cell trait (SCT). The acute low back pain is severe and can be disabling, and the condition can be confused with muscle strain, discogenic pain, stress fracture, or other problems in athletes. Our evidence shows that this syndrome is caused by lumbar paraspinal myonecrosis (LPSMN), which likely often contributes to the lumbar paraspinal compartment syndrome. We explain why we believe SCT is a risk factor for LPSMN in football conditioning/training, although SCT is not requisite for this syndrome, which has been reported rarely in other sports (e.g., snow or water skiing) and especially in weight lifting that targets lumbar muscles. The clinical course of LPSMN in football can be mild and allow return to play in a week or two, or it can be severe and lead to long-term sequelae. Knowledge of this syndrome will enable athletic trainers and team physicians to diagnose it early, treat it properly, and lessen its effect. Further research will help us learn how better to prevent it.

Challenging Return to Play Decisions: Heat Stroke, Exertional Rhabdomyolysis, and Exertional Collapse Associated With Sickle Cell Trait

Context:

Sports medicine providers frequently return athletes to play after sports-related injuries and conditions. Many of these conditions have guidelines or medical evidence to guide the decision-making process. Occasionally, however, sports medicine providers are challenged with complex medical conditions for which there is little evidence-based guidance and physicians are instructed to individualize treatment; included in this group of conditions are exertional heat stroke (EHS), exertional rhabdomyolysis (ER), and exertional collapse associated with sickle cell trait (ECAST).

Evidence Acquisition:

The MEDLINE (2000-2015) database was searched using the following search terms: exertional heat stroke, exertional rhabdomyolysis, and exertional collapse associated with sickle cell trait. References from consensus statements, review articles, and book chapters were also utilized.

Study Design:

Clinical review.

Level of Evidence:

Level 4.

Results:

These entities are unique in that they may cause organ system damage capable of leading to short- or long-term detriments to physical activity and may not lend to complete recovery, potentially putting the athlete at risk with premature return to play.

Conclusion:

With a better understanding of the pathophysiology of EHS, ER, and ECAST and the factors associated with recovery, better decisions regarding return to play may be made.

Exertional sickling: questions and controversy

Sickle cell trait (SCT) occurs in about 8% of African-Americans and is often described to be of little clinical consequence. Over time, a number of risks have emerged, and among these are rare but catastrophic episodes of sudden death in athletes and other individuals associated with physical activities which is often described as exercise collapse associated with sickle trait (ECAST). Despite an epidemiologic link between SCT and sudden death as well as numerous case reports in both medical literature and lay press, no clear understanding of the key pathophysiologic events has been identified. Strategies for identification of individuals at risk and prevention of ECAST have been both elusive and controversial. Stakeholders have advocated for different approaches to this issue particularly with regard to screening for hemoglobin S. Furthermore, the recommendations and guidelines that are in place for the early recognition of ECAST and the prevention and treatment of the illness are not well defined and remain fragmented. Among the cases identified, those in collegiate football players in the United States are often highlighted. This manuscript examines these case studies and the current recommendations to identify areas of consensus and controversy regarding recommendations for prevention, recognition and treatment of ECAST.

Investigation of Sudden Death in Athletes: The Fittest Bodies in the Morgue

Sporting events are generally viewed as regulated activities with fit and healthy participants; therefore, when deaths occur, they draw considerable public interest. Athletic participants can be considered a vulnerable population based on inherent risks within certain sports and the associated physiologic stresses, which may complicate underlying medical conditions. Sudden deaths in young athletes participating in high school and collegiate organized sports occur at an average of four to six deaths per year; however, sudden deaths related to exercise outside of an organized sport setting remain unaccounted for in the overall prevalence of these deaths. A typical forensic pathology practice will see not only these higher-profile deaths occurring during an organized sporting event, but also lower-profile occurrences of individuals dying during more recreational or unstructured exercise. Sport-related deaths can essentially be categorized as those that occur due to dangers inherent in the sport itself, such as forms of heat-related illnesses, blunt force trauma, and water-related deaths, and those that occur due to susceptibilities of a given predisposed participant, including sickle cell trait, hypertrophic cardiomyopathy, and other cardiovascular diseases. This article will address both types of vulnerabilities and provide guidance for appropriate and specific medicolegal death investigation and autopsy procedures in these deaths.

Intraday blood rheological changes induced by Ramadan fasting in sickle cell trait carriers

The goal of the present study was to test whether fasting during the holy period of Ramadan may disturb blood rheology in sickle cell trait (SCT) carriers more than in a group of subjects with normal hemoglobin. Twenty African male students participated in the study: 10 SCT carriers and 10 subjects with normal hemoglobin (CONT). Biochemical parameters (plasma glucose and lipids levels), hematocrit, blood viscosity, and urine specific gravity were measured in the two groups on the 14th day of the Ramadan period (Ramadan condition) and 6 wks after the end of Ramadan (baseline condition). All the measurements were performed twice for each experimental day to measure intraday variation: 8:00 and 18:00 h. Plasma glucose level and lipid profile were not significantly different between the two groups. Although Ramadan did not affect the lipid profile, the plasma glucose concentration was lower during the Ramadan period compared with the baseline condition in the two groups. Hematocrit and urine specific gravity did not differ between the two groups and was greater in the evening than in the morning, independently of the condition. SCT carriers had higher blood viscosity than the CONT group. However, whereas blood viscosity remained unchanged through the day in the CONT group, whatever the condition, SCT carriers were characterized by a large increase of blood viscosity in the evening during the Ramadan period, indicating higher risk for microcirculatory blood flow impairments. Specific medical recommendations are needed for SCT carriers engaged in religious fasting.

Sudden cardiac death in athletes: where do we stand

We aimed to review the literature to explore the magnitude of sudden cardiac death (SCD) in young athletes. Although SCD in athletes is not a common event, it represents a tragedy of the apparently fit young population. SCD varies according to countries, age groups, and sex. In addition, it varies in the underlying causes and the screening tool. Therefore, we are in need for further research efforts. Guidelines, public and physician awareness, and education regarding the warning signs are integral part in the strategy to reduce SCD tragedy. However, all these requirements raise concern for cost-effectiveness in some countries for proper implementation.

ACSM and CHAMP summit on sickle cell trait: mitigating risks for warfighters and athletes

INTRODUCTION

An estimated 300 million people worldwide have sickle cell trait (SCT). Although largely benign, SCT has been associated with exertional rhabdomyolysis and exercise-related sudden death in warfighters/athletes (WA). The National Collegiate Athletic Association's policy to confirm a student athlete's SCT status during their preparticipation medical examination prompted reaction from some organizations regarding the rationale and ethical justification of the policy.

METHODS

On September 26 and 27, 2011, a summit, composed of military and civilian experts in sports medicine and SCT, was convened at the Uniformed Services University in Bethesda, MD. The expert panel was charged with two objectives: 1) to provide specific recommendations to further mitigate the apparent risk with strenuous exercise in WA with SCT and 2) to develop clinical guidelines to identify, treat, and return to duty/play WA suspected to have incurred nonfatal sickle cell collapse.

RESULTS

New terminology is introduced, areas of current controversy are explored, consensus recommendations for mitigating risk and managing the WA with SCT are reviewed, and important areas for future research are identified.

CONCLUSION

Further research is needed before conclusions can be drawn regarding the etiology of the increased death rate observed in WA with SCT, and the possibility exists that SCT is a surrogate for as yet another contributing factor for the unexplained deaths.

Effects of hydration and water deprivation on blood viscosity during a soccer game in sickle cell trait carriers

The present study compared the changes in blood viscosity, hydration status, body temperature and heart rate between a group of sickle cell trait (SCT) carriers and a control (Cont) group before and after a soccer game performed in two conditions: one with water offered ad libitum (hydration condition; Hyd) and the other one without water (dehydration condition; Dehyd). Blood viscosity and haematocrit per blood viscosity ratio (HVR; an index of red blood cell oxygen transport effectiveness) were measured before and at the end of each game. Resting blood viscosity was greater in the SCT carriers than in the Cont group. The increase of blood viscosity over baseline at the end of the game in the Cont group was similar in the two conditions. In contrast, the change in blood viscosity occurring in SCT carriers during soccer games was dependant on the experimental condition: (1) in Dehyd condition, blood viscosity rose over baseline; (2) in Hyd condition, blood viscosity decreased below resting level reaching Cont values. The Cont group had higher HVR than SCT carriers at rest. HVR remained unchanged in the Cont group at the end of the games, whatever the experimental condition. Although HVR of SCT carriers decreased below baseline at the end of the game performed in Dehyd condition, it increased over resting level in Hyd condition reaching the values of the Cont group. Our study demonstrated that ad libitum hydration in exercising SCT carriers normalises the blood hyperviscosity.

Nucleation of sickle hemoglobin mixed with hemoglobin A: experimental and theoretical studies of hybrid-forming mixtures

Sickle hemoglobin (HbS) is a point mutation of the two β subunits in normal Hb (HbA) that leads to nucleated polymerization and accompanying pathology. We measured the rates of homogeneous and heterogeneous nucleation of HbS in the presence of up to 50% HbA under conditions in which hybrid HbAS molecules will also form. The replacement of 50% of HbS by HbA slows polymerization by factors of ∼100 in the physiological range, which is substantially less than previously thought. To provide a theoretical description of these data, we extended the double nucleation model for HbS polymerization to conditions in which hybridized mixtures are present. Measurements of homogeneous nucleation and the theory agree only when at least one of the molecules in the nucleus is not a hybrid. We attribute this to the necessary presence in the nucleus of a molecule that utilizes both β-subunit mutation sites in intermolecular contacts, whereas the remaining molecules engage only one of the mutation sites. Heterogeneous nucleation appears to require an even greater number of nonhybrid molecules, presumably because of the need for the nucleus to attach to the polymer as well as to form internal bonds. These results also provide insights into the pathophysiology of sickle cell disease, including the occasional severe events that strike persons in whom both HbS and HbA are expressed, a condition known as sickle trait. The studies reported here are necessary for understanding physiologically relevant polymerization in the presence of ligands as well as therapeutically relevant copolymerizing inhibitors.

A policy impact analysis of the mandatory NCAA sickle cell trait screening program

OBJECTIVE

To estimate the impact of the mandatory National Collegiate Athletic Association (NCAA) sickle cell trait (SCT) screening policy on the identification of sickle cell carriers and prevention of sudden death.

DATA SOURCE

We used NCAA reports, population-based SCT prevalence estimates, and published risks for exercise-related sudden death attributable to SCT.

STUDY DESIGN

We estimated the number of sickle cell carriers identified and the number of potentially preventable sudden deaths with mandatory SCT screening of NCAA Division I athletes. We calculated the number of student-athletes with SCT using a conditional probability based upon SCT prevalence data and self-identified race/ethnicity status. We estimated sudden deaths over 10 years based on published attributable risk of exercise-related sudden death due to SCT.

PRINCIPAL FINDINGS

We estimate that over 2,000 NCAA Division I student-athletes with SCT will be identified under this screening policy and that, without intervention, about seven NCAA Division I student-athletes would die suddenly as a complication of SCT over a 10-year period.

CONCLUSION

Universal sickle cell screening of NCAA Division I student-athletes will identify a substantial number of sickle cell carriers. A successful intervention could prevent about seven deaths over a decade.