Sickle Cell Trait, Rhabdomyolysis, and Mortality among U.S. Army Soldiers

Exertional rhabdomyolysis among active component members of the U.S. Armed Forces, 2019-2023

A largely preventable condition, exertional rhabdomyolysis persists as an occupational hazard of military training and operations, especially in high heat environments among individuals exerting themselves to their physical endurance limits. During the 5-year surveillance period of this study, unadjusted incidence rates of exertional rhabdomyolysis per 100,000 person-years among U.S. active component service members fluctuated, reaching a low of 38.0 cases in 2020 and peaking at 40.5 cases in 2023. The rate in 2020 constituted a decline of 3.8% from the rate in 2019 (39.5 cases). Beginning in 2020, incidence rates per 100,000 person-years gradually increased, by 1.8% in 2021 (38.7 cases), 5.3% in 2022 (40.0 cases), and 6.6% in 2023 (40.5 cases). Consistent with prior reports, subgroup-specific crude rates in 2023 were highest among men, those less than 20 years old, non-Hispanic Black service members, Marine Corps or Army members, and those in combat-specific and 'other' occupations. Recruits experienced the highest rates of exertional rhabdomyolysis during each year, with incidence rates 6 to 10 times greater than all other service members.

Genome-Wide Analysis of Exertional Rhabdomyolysis in Sickle Cell Trait Positive African Americans

Sickle cell trait (SCT), although generally a benign carrier state of hemoglobin S (HbAS), is a risk factor for exertional rhabdomyolysis (ERM), a rare but potentially fatal consequence of highly intense physical exercise, particularly among active-duty military personnel and high-performance athletes. The association between SCT and ERM is poorly understood. The objective of this study was to elucidate the genetic basis of ERM in an SCT-positive African American cohort. SCT-positive African Americans with a personal history of ERM (cases, n = 30) and without history of ERM (controls, n = 53) were enrolled in this study. Whole-genome sequencing was performed on DNA samples isolated from peripheral white blood cells. Participants' demographic, behavioral, and medical history information was obtained. An additional 131 controls were extracted from SCT-positive subjects of African descent from the 1000 Genomes Project. SCT carriers with ERM were characterized by myotoxicity features, significant muscle involvement dominated by muscle weakness, and severe pain and substantial increase in serum creatine kinase, with a mean value of 50,480 U/L. A distinctive feature of the SCT individuals with ERM was exertional collapse, which was reported in 53.3% of the cases in the study cohort. An important factor for the development of ERM was the duration and frequency of strenuous physical activity in the cases compared to the controls. Whole-genome sequencing identified 79,696 protein-coding variants. Genome-wide association analysis revealed that the p.C477R, rs115958260 variant in the SLC44A3 gene was significantly associated with ERM event in SCT-positive African Americans. The study results suggest that a combination of vigorous exercise and a genetic predisposing factor is involved in ERM.

Blood rheology and vascular function in sickle cell trait and sickle cell disease: From pathophysiological mechanisms to clinical usefulness

Sickle cell disease (SCD) is an autosomal recessive disorder. Although the molecular mechanisms at the origin of SCD have been well characterized, its clinical expression is highly variable. SCD is characterized by blood rheological abnormalities, increased inflammation and oxidative stress, and vascular dysfunction. Individuals with only one copy of the mutated β-globin gene have sickle cell trait (SCT) and are usually asymptomatic. The first part of this review focuses on the biological responses of SCT carriers during exercise and on the effects of combined SCT and diabetes on vascular function, several biomarkers and clinical complications. The second part of the review focuses on SCD and shows that the magnitude of red blood cell (RBC) rheological alterations is highly variable from one patient to another, and this variability reflects the clinical and hematological variability: patients with the less deformable RBCs have high hemolytic rate and severe anemia, and are prone to develop leg ulcers, priapism, cerebral vasculopathy, glomerulopathy or pulmonary hypertension. In contrast, SCD patients characterized by the presence of more deformable RBCs (but still rigid) are less anemic and may exhibit increased blood viscosity, which increases the risk for vaso-occlusive events. Several genetic and cellular factors may modulate RBC deformability in SCD: co-existence of α-thalassemia, fetal hemoglobin level, oxidative stress, the presence of residual mitochondria into mature RBCs, the activity of various non-selective cationic ion channels, etc. The last part of this review presents the effects of hydroxyurea and exercise training on RBC rheology and other biomarkers in SCD.

Differences in the Circulating Proteome in Individuals with versus without Sickle Cell Trait

BACKGROUND

Sickle cell trait affects approximately 8% of Black individuals in the United States, along with many other individuals with ancestry from malaria-endemic regions worldwide. While traditionally considered a benign condition, recent evidence suggests that sickle cell trait is associated with lower eGFR and higher risk of kidney diseases, including kidney failure. The mechanisms underlying these associations remain poorly understood. We used proteomic profiling to gain insight into the pathobiology of sickle cell trait.

METHODS

We measured proteomics ( N =1285 proteins assayed by Olink Explore) using baseline plasma samples from 592 Black participants with sickle cell trait and 1:1 age-matched Black participants without sickle cell trait from the prospective Women's Health Initiative cohort. Age-adjusted linear regression was used to assess the association between protein levels and sickle cell trait.

RESULTS

In age-adjusted models, 35 proteins were significantly associated with sickle cell trait after correction for multiple testing. Several of the sickle cell trait-protein associations were replicated in Black participants from two independent cohorts (Atherosclerosis Risk in Communities study and Jackson Heart Study) assayed using an orthogonal aptamer-based proteomic platform (SomaScan). Many of the validated sickle cell trait-associated proteins are known biomarkers of kidney function or injury ( e.g. , hepatitis A virus cellular receptor 1 [HAVCR1]/kidney injury molecule-1 [KIM-1], uromodulin [UMOD], ephrins), related to red cell physiology or hemolysis (erythropoietin [EPO], heme oxygenase 1 [HMOX1], and α -hemoglobin stabilizing protein) and/or inflammation (fractalkine, C-C motif chemokine ligand 2/monocyte chemoattractant protein-1 [MCP-1], and urokinase plasminogen activator surface receptor [PLAUR]). A protein risk score constructed from the top sickle cell trait-associated biomarkers was associated with incident kidney failure among those with sickle cell trait during Women's Health Initiative follow-up (odds ratio, 1.32; 95% confidence interval, 1.10 to 1.58).

CONCLUSIONS

We identified and replicated the association of sickle cell trait with a number of plasma proteins related to hemolysis, kidney injury, and inflammation.

Evaluating the impact of sickle cell disease on COVID-19 susceptibility and severity: a retrospective cohort study based on electronic health record

Background

Sickle cell trait/disease (SCT/SCD) are enriched among Black people and associated with various comorbidities. The overrepresentation of these characteristics prevents traditional regression approach obtaining convincing evidence for the independent effect of SCT/SCD on other health outcomes. This study aims to investigate the association between SCT/SCD and COVID-19-related outcomes using causal inference approaches that balance the covariate.

Methods

We leveraged electronic health record (EHR) data from the University of Chicago Medicine between March 2020 and December 2021. Demographic characteristics were retrieved. Medical conditions were identified using ICD-10 codes. Five approaches, including two traditional regression approaches (unadjusted and adjusted) and three causal inference approaches [covariate balancing propensity score (CBPS) matching, CBPS weighting, and CBPS adjustment], were employed.

Results

A total of 112,334 patients were included in the study, among which 504 had SCT and 388 SCD. Patients with SCT/SCD were more likely to be non-Hispanic Black people, younger, female, non-smokers, and had a diagnosis of diabetes, heart failure, asthma, and cerebral infarction. Causal inference approaches achieved a balanced distribution of these covariates while traditional approaches failed. Across these approaches, SCD was consistently associated with COVID-19-related pneumonia (odds ratios (OR) estimates, 3.23 (95% CI: 2.13-4.89) to 2.57 (95% CI: 1.10-6.00)) and pain (OR estimates, 6.51 (95% CI: 4.68-9.06) to 2.47 (95% CI: 1.35-4.49)). While CBPS matching suggested an association between SCD and COVID-19-related acute respiratory distress syndrome (OR = 2.01, 95% CI: 0.97-4.17), this association was significant in other approaches (OR estimates, 2.96 (95% CI: 1.69-5.18) to 2.50 (95% CI: 1.43-4.37)). No association was observed between SCT and COVID-19-related outcomes in causal inference approaches.

Conclusion

Using causal inference approaches, we provide comprehensive evidence for the link between SCT/SCD and COVID-19-related outcomes.

Development and Validation of a Renal Replacement after Trauma Scoring Tool

BACKGROUND

Stress on the healthcare system requires careful allocation of resources such as renal replacement therapy (RRT). The COVID-19 pandemic generated difficulty securing access to RRT for trauma patients. We sought to develop a renal replacement after trauma (RAT) scoring tool to help identify trauma patients who may require RRT during their hospitalization.

STUDY DESIGN

The 2017 to 2020 TQIP database was divided into a derivation (2017 to 2018 data) and validation (2019 to 2020 data) set. A 3-step methodology was used. Adult trauma patients admitted from the emergency department to the operating room or ICU were included. Patients with chronic kidney disease, transfers from another hospital, and emergency department death were excluded. Multiple logistic regression models were created to determine the risk for RRT in trauma patients. The weighted average and relative impact of each independent predictor was used to derive a RAT score, which was validated using area under receiver operating characteristic curve (AUROC).

RESULTS

From 398,873 patients in the derivation and 409,037 patients in the validation set, 11 independent predictors of RRT were included in the RAT score derived with scores ranging from 0 to 11. The AUROC for the derivation set was 0.85. The rate of RRT increased to 1.1%, 3.3%, and 20% at scores of 6, 8, and 10, respectively. The validation set AUROC was 0.83.

CONCLUSIONS

RAT is a novel and validated scoring tool to help predict the need for RRT in trauma patients. With future improvements including baseline renal function and other variables, the RAT tool may help prepare for the allocation of RRT machines/staff during times of limited resources.

Management of the Sickle Cell Trait: An Opinion by Expert Panel Members

The number of individuals with the sickle cell trait exceeds 300 million worldwide, making sickle cell disease one of the most common monogenetic diseases globally. Because of the high frequency of sickle cell disease, reproductive counseling is of crucial importance. In addition, unlike other carrier states, Sickle Cell Trait (SCT) seems to be a risk factor for several clinical complications, such as extreme exertional injury, chronic kidney disease, and complications during pregnancy and surgery. This expert panel believes that increasing knowledge about these clinical manifestations and their prevention and management can be a useful tool for all healthcare providers involved in this issue.

Rhabdomyolysis aggravates renal iron accumulation and acute kidney injury in a humanized mouse model of sickle cell disease

Individuals with sickle cell disease (SCD) are at greater risk of rhabdomyolysis, a potentially life-threatening condition resulting from the breakdown of skeletal muscle fibers. Acute kidney injury (AKI) is one of the most severe complications of rhabdomyolysis. Chronic kidney and cardiovascular disease, which account for SCD mortality, are long-term consequences of AKI. Although SCD elevates the risks of rhabdomyolysis-induced sudden death, the mechanisms that underlie rhabdomyolysis-induced AKI in SCD are unclear. In the present study, we show that, unlike their control non-sickling (AA) counterparts, transgenic homozygous SCD (SS; Townes model) mice exhibited 100% mortality 8-24 h after intramuscular glycerol injection. Five hours after glycerol injection, SS mice showed a more significant increase in myoglobinuria and plasma creatine kinase levels than AA mice. Basal plasma heme and kidney tissue iron levels were significantly higher in SS than in AA mice. In contrast to AA, glycerol-induced rhabdomyolysis aggravated these parameters in SS mice. Rhabdomyolysis also amplified oxidative stress in SS compared to AA mice. Glycerol-treated SS mice exhibited worse renal function, exemplified by a reduction in GFR with a corresponding increase in plasma and urinary biomarkers of early AKI and renal tubular damage. The free radical scavenger and Fenton chemistry inhibitor, TEMPOL, ameliorated rhabdomyolysis-induced AKI in the SS mice. These findings demonstrate that oxidative stress driven by renal iron accumulation amplifies rhabdomyolysis-induced AKI in SCD mice.

Sickle Cell Anemia Associated With Increased In-Hospital Mortality in Post-Cardiac Arrest Patients

Introduction Sickle cell anemia (SCA) is a hemoglobinopathy that arises from a point mutation in the beta-globin gene, which causes the polymerization of deoxygenated hemoglobin that leads to a wide variety of clinical complications. Deaths in patients with SCA most commonly arise from renal, cardiovascular disease, infections, and stroke. In-hospital cardiac arrest has been found to be more common in older patients and those on ventilatory life support, among others. This study aims to provide more insight into how SCA affects the risk of in-hospital mortality in post-cardiac arrest patients. Methods The National Inpatient Survey database years 2016 to 2019 was utilized. The International Classification of Diseases, Tenth Revision, Procedure Coding System (ICD-10 PCS) codes for cardiopulmonary resuscitation were used to identify in-hospital cardiac arrest (IHCA) patients. ICD-10 Clinical Modification (CM) codes were used to identify SCA and other medical comorbidities. Categorical data was compared using Person's chi-square test, and continuous variables were compared using the independent samples t-test. Multinomial logistic regression was used to study the effects of SCA on post-arrest in-hospital mortality controlling for age, Charlson comorbidity score, and demographic variables. Binomial logistic regression models for dichotomous variables were utilized in the subgroup and secondary outcomes analysis. Results In patients with IHCA, patients who had SCA were found to have a significantly increased risk of in-hospital mortality adjusted for baseline characteristics and Charlson comorbidity score (OR: 1.16, 95% CI: 1.02-1.32, p=0.0025). Patient characteristics most strongly associated with an increased risk of in-hospital mortality in this cohort were found to be Black race (OR: 1.92, 95% CI: 1.87-1.97, p<0.001) and self-payer status (OR: 2.14, 95% CI: 2.06-2.22, p<0.001). Subgroup analysis revealed only patients with sickle cell disease had a statistically significant increased risk of in-hospital mortality in this cohort (OR: 4.41, 95% CI: 3.5-5.55, p<0.001), and patients with sickle cell trait did not. Conclusion In patients with IHCA, SCA is associated with an increased risk of in-hospital mortality. This risk was confined to patients with sickle cell disease and not patients with sickle cell trait.

Universal Training Precautions: A Review of Evidence and Recommendations for Prevention of Exercise-Related Injury, Illness, and Death in Warfighters and Athletes

Facing pressure to train for victory, warfighters and athletes encounter numerous health risks that are directly related to their regular physical training. The concept of universal training precautions (UTPs) signifies universal processes designed to prevent unnecessary bodily harm, including injury, illness, and death, during physical training programs. Although no formal guidelines exist for collectively implementing a defined set of UTPs to address a broad scope of exercise-related health risks, recommendations and guidelines have been published relating to preventing sudden death during high school sports and collegiate conditioning sessions. A long list of critical topics must be considered as UTPs, including physical fitness factors, transition-period accommodation, hydration, environmental factors and acclimatization, appropriate recovery, use of medications and dietary supplements, and importantly, leadership. In this article, we outline in detail, with corresponding Strength of Recommendation Taxonomy ratings, what should be considered universal recommendations to minimize the risk of warfighters and athletes coming to harm when participating in group physical activities.

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

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.

Sickle Cell Trait, Clinical Manifestations and Outcomes: A Cross-Sectional Study in Colombia: Increasing Rate of Symptomatic Subjects Living in High Altitude

Background

Sickle cell trait (SCT) is an autosomal recessive blood disorder in which patients are heterozygous carriers for hemoglobin S (HbAS) and are usually asymptomatic. We performed a descriptive analysis of clinical manifestations and outcomes associated with SCT.

Methods

This was a descriptive, cross-sectional study that included patients with SCT from 2014 to 2020 at Hospital Militar Central, the reference center of the Military forces in Bogota, Colombia.

Results

Of 647 hemoglobin electrophoresis analyzed, we identified 51 patients with SCT, including 43 males (84.3%) and eight females (15.7%), with a median age of 22 years (IQR 15-36 years). Of these, 28 (54.8%) were Afro-Colombian, 23 (45.1%) were Colombian mestizos, and 31/51 (60.8%) of patients were active military members. Twenty-four patients (47.1%) were asymptomatic, and Twenty-seven patients (52.9%) were symptomatic (systemic complications); Most of the patients who presented symptoms were active military members of the Colombian military forces. Splenic complications were the most important (85.2%), p=0.0005, and there was a wide spectrum of splenic complications. In addition, we found significant elevations in leukocytes, bilirubin, LDH, and CRP. Eighteen patients (66.7%) received medical management, five (18.5%) required splenectomy, and only 5.9% of patients were sent for genetic counseling.

Conclusions

Military Personnel is a population with a high risk of developing symptoms, and splenic complications were the most relevant in symptomatic patients. Most patients received medical treatment, and 18.5% of patients required splenectomy. Our results reflect the absence of redirection of these patients to genetic counseling.

Sickle Cell Disease in Children and Adolescents: A Review of the Historical, Clinical, and Public Health Perspective of Sub-Saharan Africa and Beyond

Sickle cell disease (SCD) is an umbrella term for a group of life-long debilitating autosomal recessive disorders that are caused by a single-point mutation (Glu→Val) that results in polymerization of hemoglobin (Hb) and reversible sickle-shape deformation of erythrocytes. This leads to increased hemolysis of erythrocytes and microvascular occlusion, ischemia-reperfusion injury, and tissue infarction, ultimately causing multisystem end-organ complications. Sickle cell anemia (HbSS) is the most common and most severe genotype of SCD, followed by HbSC, HbSβ⁰thalassemia, HbSβ+thalassemia, and rare and benign genotypes. Clinical manifestations of SCD occur early in life, are variable, and are modified by several genetic and environmental factors. Nearly 500 children with SCD continue to die prematurely every day, due to delayed diagnosis and/or lack of access to comprehensive care in sub-Saharan Africa (SSA), a trend that needs to be urgently reversed. Despite proven efficacy in developed countries, newborn screening programs are not universal in SSA. This calls for a consolidated effort to make this possible, through the use of rapid, accurate, and cheap point-of-care test kits which require minimal training. For almost two decades, hydroxyurea (hydroxycarbamide), a century-old drug, was the only disease-modifying therapy approved by the U.S. Food and Drug Administration. Recently, the list expanded to L-glutamine, crizanlizumab, and voxelotor, with several promising novel therapies in the pipeline. Despite its several limitations, hematopoietic stem cell transplant (HSCT) remains the only curative intervention for SCD. Meanwhile, recent advances in gene therapy trials offer a glimpse of hope for the near future, although its use maybe limited to developed countries for several decades.

COVID-19 outcomes in sickle cell disease and sickle cell trait

Throughout the Coronavirus Disease 2019 (COVID-19) pandemic, understanding the effects of COVID-19 on persons with Sickle Cell Disease (SCD) and Sickle Cell Trait (SCT) has garnered interest. Patients with SCD diagnosed with COVID-19 utilize the emergency department and are hospitalized at significantly higher rates compared to the general population, with vaso-occlusive crisis and acute chest syndrome as the leading presentations. Whether SCD alone increases the likelihood of severe COVID-19 illness remains uncertain; however, potential risk factors for severe disease among patients with SCD include older age, frequent acute care visits for pain, haemoglobin SC disease, and pre-existing end-organ disease. SCT status may also influence COVID-19 outcomes, particularly among those with pre-existing co-morbidities. Corticosteroids in patients with SCD and COVID-19 should be used with extreme caution given strong associations between corticosteroid exposure and severe vaso-occlusive crisis, with prophylactic transfusion administered if corticosteroids are deemed necessary. Hydroxyurea may be protective in COVID-19.

Silent Infarcts, White Matter Integrity, and Oxygen Metabolic Stress in Young Adults With and Without Sickle Cell Trait

BACKGROUND

Individuals with sickle cell anemia have heightened risk of stroke and cognitive dysfunction. Given its high prevalence globally, whether sickle cell trait (SCT) is a risk factor for neurological injury has been of interest; however, data have been limited. We hypothesized that young, healthy adults with SCT would show normal cerebrovascular structure and hemodynamic function.

METHODS

As a case-control study, young adults with (N=25, cases) and without SCT (N=24, controls) underwent brain magnetic resonance imaging to quantify brain volume, microstructural integrity (fractional anisotropy), silent cerebral infarcts (SCI), intracranial stenosis, and aneurysms. Pseudocontinuous arterial spin labeling and asymmetric spin echo sequences measured cerebral blood flow and oxygen extraction fraction, respectively, from which cerebral metabolic oxygen demand was calculated. Imaging metrics were compared between SCT cases and controls. SCI volume was correlated with baseline characteristics.

RESULTS

Compared with controls, adults with SCT demonstrated similar normalized brain volumes (SCT 0.80 versus control 0.81, P=0.41), white matter fractional anisotropy (SCT 0.41 versus control 0.43, P=0.37), cerebral blood flow (SCT 62.04 versus control, 61.16 mL/min/100 g, P=0.67), oxygen extraction fraction (SCT 0.27 versus control 0.27, P=0.31), and cerebral metabolic oxygen demand (SCT 2.71 versus control 2.70 mL/min/100 g, P=0.96). One per cohort had an intracranial aneurysm. None had intracranial stenosis. The SCT cases and controls showed similar prevalence and volume of SCIs; however, in the subset of participants with SCIs, the SCT cases had greater SCI volume versus controls (0.29 versus 0.07 mL, P=0.008). Of baseline characteristics, creatinine was mildly elevated in the SCT cohort (0.9 versus 0.8 mg/dL, P=0.053) and correlated with SCI volume (ρ=0.49, P=0.032). In the SCT cohort, SCI distribution was similar to that of young adults with sickle cell anemia.

CONCLUSIONS

Adults with SCT showed normal cerebrovascular structure and hemodynamic function. These findings suggest that healthy individuals with SCT are unlikely to be at increased risk for early or accelerated ischemic brain injury.

Trends in Pediatric Rhabdomyolysis and Associated Renal Failure: A 10-Year Population-Based Study

OBJECTIVES

Rhabdomyolysis in children is a highly variable condition with presentations ranging from myalgias to more severe complications like acute renal failure. We sought to explore demographics and incidence of pediatric rhabdomyolysis hospitalizations and rates of associated renal failure, as our current understanding is limited.

METHODS

This was a retrospective analysis using the Healthcare Cost and Utilization Project Kids' Inpatient Database to identify children hospitalized with a primary diagnosis of rhabdomyolysis. Data were analyzed for demographic characteristics, as well as geographic and temporal trends. Multivariable logistic regression was used to identify characteristics associated with rhabdomyolysis-associated acute renal failure.

RESULTS

From 2006 to 2016, there were 8599 hospitalized children with a primary diagnosis of rhabdomyolysis. Overall, hospitalizations for pediatric rhabdomyolysis are increasing over time, with geographic peaks in the South and Northeast regions, and seasonal peaks in March and August. Though renal morbidity was diagnosed in 8.5% of children requiring hospitalization for rhabdomyolysis, very few of these patients required renal replacement therapy (0.41%), and death was rare (0.03%). Characteristics associated with renal failure included male sex, age greater than 15 years, and non-Hispanic Black race.

CONCLUSIONS

Though renal failure occurs at a significant rate in children hospitalized with rhabdomyolysis, severe complications, including death, are rare. The number of children hospitalized with rhabdomyolysis varies by geographic region and month of the year. Future studies are needed to explore etiologies of rhabdomyolysis and laboratory values that predict higher risk of morbidity and mortality in children with rhabdomyolysis.

Association of Kidney Comorbidities and Acute Kidney Failure With Unfavorable Outcomes After COVID-19 in Individuals With the Sickle Cell Trait

Importance

Sickle cell trait (SCT), defined as the presence of 1 hemoglobin beta sickle allele (rs334-T) and 1 normal beta allele, is prevalent in millions of people in the US, particularly in individuals of African and Hispanic ancestry. However, the association of SCT with COVID-19 is unclear.

Objective

To assess the association of SCT with the prepandemic health conditions in participants of the Million Veteran Program (MVP) and to assess the severity and sequelae of COVID-19.

Design, Setting, and Participants

COVID-19 clinical data include 2729 persons with SCT, of whom 353 had COVID-19, and 129 848 SCT-negative individuals, of whom 13 488 had COVID-19. Associations between SCT and COVID-19 outcomes were examined using firth regression. Analyses were performed by ancestry and adjusted for sex, age, age squared, and ancestral principal components to account for population stratification. Data for the study were collected between March 2020 and February 2021.

Exposures

The hemoglobin beta S (HbS) allele (rs334-T).

Main Outcomes and Measures

This study evaluated 4 COVID-19 outcomes derived from the World Health Organization severity scale and phenotypes derived from International Classification of Diseases codes in the electronic health records.

Results

Of the 132 577 MVP participants with COVID-19 data, mean (SD) age at the index date was 64.8 (13.1) years. Sickle cell trait was present in 7.8% of individuals of African ancestry and associated with a history of chronic kidney disease, diabetic kidney disease, hypertensive kidney disease, pulmonary embolism, and cerebrovascular disease. Among the 4 clinical outcomes of COVID-19, SCT was associated with an increased COVID-19 mortality in individuals of African ancestry (n = 3749; odds ratio, 1.77; 95% CI, 1.13 to 2.77; P = .01). In the 60 days following COVID-19, SCT was associated with an increased incidence of acute kidney failure. A counterfactual mediation framework estimated that on average, 20.7% (95% CI, -3.8% to 56.0%) of the total effect of SCT on COVID-19 fatalities was due to acute kidney failure.

Conclusions and Relevance

In this genetic association study, SCT was associated with preexisting kidney comorbidities, increased COVID-19 mortality, and kidney morbidity.

Lower Muscle and Blood Lactate Accumulation in Sickle Cell Trait Carriers in Response to Short High-Intensity Exercise

It remains unclear whether sickle cell trait (SCT) should be considered a risk factor during intense physical activity. By triggering the polymerization-sickling-vaso-occlusion cascade, lactate accumulation-associated acidosis in response to high-intensity exercise is believed to be one of the causes of complications. However, our understanding of lactate metabolism in response to high-intensity exercise in SCT carriers is incomplete. Thirty male SCT carriers (n = 15) and healthy subjects (n = 15) with and without α-thalassemia performed a 2-min high-intensity exercise. Blood and muscle lactate concentrations were measured at exercise completion. Time courses of blood lactate and glucose concentrations were followed during the subsequent recovery. Additional biochemical analyses were performed on biopsies of the vastus lateralis muscle. SCT was associated with lower blood and muscle lactate concentrations in response to the short high-intensity exercise. Compared to controls, the muscle content among SCT carriers of lactate transporter MCT4 and β2-adrenergic receptor were higher and lower, respectively. During recovery, the lactate removal ability was higher in SCT carriers. In the present study, no effect of α-thalassemia was observed. The lower blood and muscle lactate accumulations in SCT carriers may, to some extent, act as protective mechanisms: (i) against exercise-related acidosis and subsequent sickling, that may explain the relatively rare complications observed in exercising SCT carriers; and (ii) against the deleterious effects of intracellular lactate and associated acidosis on muscle function, that might explain the elevated presence of SCT carriers among the best sprinters.

Impact of sickle cell trait on morbidity and mortality from SARS-CoV-2 infection

There is no impact of SCT on respiratory, renal, or circulatory complications or mortality in patients with SARS-CoV-2 infection.

The prevalence of SCT in the hospitalized cohort was significantly higher than the prevalence in the community (12% vs 7.31%).

The COVID-19 pandemic has highlighted racial health disparities within the United States. Although social determinants of health are the most likely drivers of this disparity, it is possible that genetic traits enriched in the black population like sickle cell trait (SCT) could worsen the morbidity and mortality of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Patients admitted for SARS-CoV-2 infection who identified as black or African American were included in the study (n = 166). Blood remnants were tested for SCT, and clinical data were abstracted from the chart. There was no difference in mortality between those with SCT and those without. There was no difference in respiratory complications between groups, but those without SCT had a much higher burden of chronic lung disease (P = .004). Those with SCT had higher creatinine on admission (P = .004), but no difference in in-hospital renal complications (P = .532). Notably, 12% of the cohort had SCT, which is higher than the expected 7.31% (P = .025). Our study did not show any evidence of increased end organ damage, morbidity, or mortality from SARS-CoV-2 infection among patients with SCT but did show differences in admission creatinine and preexisting lung disease.

Challenging the dogma of the healthy heterozygote: Implications for newborn screening policies and practices

Heterozygous (carrier) status for an autosomal recessive condition is traditionally considered to lack significance for an individual's health, but this assumption has been challenged by a growing body of evidence. Carriers of several autosomal recessive disorders and some X-linked diseases are potentially at risk for the pathology manifest in homozygotes. This minireview provides an overview of the literature regarding health risks to carriers of two common autosomal recessive conditions on the Recommended Uniform Screening Panel: sickle cell disease [sickle cell trait (SCT)] and cystic fibrosis (CF). We also consider and comment on bioethical and policy implications for newborn blood screening (NBS). Health risks for heterozygotes, while relatively low for individuals, are often influenced by intrinsic (e.g., other genomic variants or co-morbidities) and extrinsic (environmental) factors, which present opportunities for personalized genomic medicine and risk counseling. They create a special challenge, however, for developing screening/follow-up policies and for genetic counseling, particularly after identification and reporting of heterozygote status through NBS. Although more research is needed, this minireview of the SCT and CF literature to date leads us to propose that blanket terms such as "healthy heterozygotes" or "unaffected carriers" should be superseded in communications about NBS results, in favor of a more nuanced paradigm of setting expectations for health outcomes with "genotype-to-risk." In the molecular era of NBS, it remains clear that public health needs to become better prepared for the full range of applied genetics.

An investigation of sickle cell trait, body mass index, and fitness in relation to venous thromboembolism among African American adults

BACKGROUND

The relationships of sickle cell trait (SCT), body mass index (BMI), and physical fitness to venous thromboembolism (VTE) in young adults have received little attention.

OBJECTIVES

To test for associations among SCT, BMI, fitness, and VTE.

PATIENTS/METHODS

We conducted a retrospective cohort study of 48,316 SCT-tested, African American individuals in the US Army during 2011-14. We used Cox proportional hazards models to compute adjusted hazards of deep vein thrombosis (DVT) and pulmonary embolism (PE) associated with selected factors.

RESULTS

Incidence rates of DVT and PE were 1.09 and 0.91 cases per 1000 person-years, respectively. Adjusted hazard ratios (aHRs) for DVT for men and women with SCT were 0.9 (95% confidence interval [CI]: 0.4-2.0; P = .711) and 1.51 (CI: 0.7-3.2; P = .274), respectively. aHRs for PE for SCT+ men and women were 1.1 (CI: 0.5-2.4; P = .773) and 1.2 (CI: 0.5-3.1; P = .650), respectively. Low physical fitness was associated with DVT and PE in women (DVT aHR =3.1; CI: 1.4-6.5; P = .004; PE aHR =4.6; CI: 2.1-9.9; P < .001) and DVT in men (aHR =2.2; CI: 1.0-4.6; P = .048). Recent weight gain of 1 or more BMI points was associated with DVT in men (aHR =1.8; CI: 1.1-2.8; P = .017).

CONCLUSIONS

We found no evidence of increased VTE risk associated with SCT in this population. However, lower fitness levels and BMI increases were so associated.

Fatal sickling-associated microvascular occlusive crisis in a young with sickle cell trait

Sickle cell trait (SCT), a heterozygous state characterized by hemoglobin AS, occurs commonly in sub-Saharan Africa, South America, Central America, India, and the Mediterranean countries. SCT is compatible with a normal lifespan and is not commonly regarded as a cause of morbid illness or death compared to its homozygous counterpart. We describe a case of fatal sickling-associated microvascular crisis, identified on post mortem evaluation in a previously undiagnosed 21-year-old military recruit with sickle cell trait. The individual presented with repeated syncope episodes during his training and was autopsied in the pursuit of cardiac anomalies and heat syncope. During the terminal episode, he collapsed and died of severe metabolic complications as he struggled to complete an organized run during routine training activities. To our knowledge, this is the first report of fatal sickling-associated crisis in a military recruit with sickle cell trait from India. This case serves to remind all armed forces and sports physicians of the importance of screening a recruit who is unable to complete exertional physical training for the presence of sickle cell trait.

Increased Rates of Rhabdomyolysis in Male Hematopoietic Cell Transplantation Recipients Taking Sirolimus and Trimethoprim/Sulfamethoxazole

Hematopoietic cell transplantation (HCT) offers long-term cure against early morbidity and mortality of hemoglobinopathies, such as sickle cell disease (SCD) and beta-thalassemia. Following HCT, sirolimus is an immunosuppressant used to prevent graft-versus-host disease (GVHD) while receiving trimethoprim-sulfamethoxazole (TMP-SMX) for Pneumocystis jirovecii prophylaxis and other antimicrobial agents (including acyclovir). One rare adverse event associated with both drugs is rhabdomyolysis, defined as creatine kinase (CK) elevation at least 5 to 10 times the upper limit of normal. This study was conducted to evaluate the rate of and risk factors for developing rhabdomyolysis in the post-HCT setting. Across 4 haploidentical and matched related donor (MRD) nonmyeloablative protocols, CK levels were prospectively monitored and patients were retrospectively identified for rhabdomyolysis. The rhabdomyolysis was graded based on the severity of CK elevation and other organ injury. At diagnosis, patients were queried for concurrent medication use (ie, sirolimus, TMP-SMX, acyclovir, or statins), sex, age, donor genotype, and time from transplantation. Among 127 patients with mostly SCD, rhabdomyolysis occurred in 22 (17%), including 2 recipients of haploidentical donor HCT and 20 recipients of MRD HCT. The time to the development of rhabdomyolysis was 61 and 73 days for the 2 recipients of haploidentical HCT and a median of 73 days for the MRD HCT recipients. Among the 22 patients who developed rhabdomyolysis, 20 (91%) were receiving sirolimus (2 haploidentical HCT recipients and 18 MRD HCT recipients), and 14 (64%) were also receiving TMP-SMX (all in the MRD HCT group). Seventy-five percent of the haploidentical donors and 69% of the MRDs had sickle cell trait. All but 2 patients with rhabdomyolysis were male. No patients who developed rhabdomyolysis were receiving statins at any point. Higher-than-expected rates of rhabdomyolysis were found post-transplantation for patients with SCD and beta-thalassemia. Contributing risk factors included immunosuppression with sirolimus, TMP-SMX, male sex, and sickle trait donor. These factors differ from the excessive muscle strain or injury, seizures, infections, or HMG-CoA inhibitors typically identified in non-HCT recipients.

A rare case of compartment syndrome and myonecrosis in a patient with hemoglobin SC disease

Myonecrosis and compartment syndrome are rarely seen in sickle cell disease (SCD), and they have not been previously reported in HbSC disease. This case can potentially be recognized as the first case of a patient with HbSC presenting with spontaneous myonecrosis and compartment syndrome.

Risk factors and future directions for preventing and diagnosing exertional rhabdomyolysis

Exertional rhabdomyolysis may occur when an individual is subjected to strenuous physical exercise. It is occasionally associated with myoglobinuria (i.e. "cola-colored" urine) alongside muscle pain and weakness. The pathophysiology of exertional rhabdomyolysis involves striated muscle damage and the release of cellular components into extracellular fluid and bloodstream. This can cause acute renal failure, electrolyte abnormalities, arrhythmias and potentially death. Exertional rhabdomyolysis is observed in high-performance athletes who are subjected to intense, repetitive and/or prolonged exercise but is also observed in untrained individuals and highly trained or elite groups of military personnel. Several risk factors have been reported to increase the likelihood of the condition in athletes, including: viral infection, drug and alcohol abuse, exercise in intensely hot and humid environments, genetic polymorphisms (e.g. sickle cell trait and McArdle disease) and epigenetic modifications. This article reviews several of these risk factors and proposes screening protocols to identify individual susceptibility to exertional rhabdomyolysis as well as the relevance of proteomics for the evaluation of potential biomarkers of muscle damage.

Anemia at Altitude: Thalassemia, Sickle Cell Disease, and Other Inherited Anemias

DeLoughery, Thomas G. Anemia at altitude-thalassemia, sickle cell disease, and other inherited anemias. High Alt Med Biol. 22: 113-118, 2021.-Anemia due to any etiology is a common medical condition throughout the world. This article discusses the most common inherited anemia types-sickle cell disease and trait, thalassemia, hereditary spherocytosis, and glucose-6-phosphate dehydrogenase deficiency. The implications of anemia for travel at altitude are discussed, and suggestions for counsel and preparations for such travel are presented.

Clinical Practice Guidelines for Exertional Rhabdomyolysis: A Military Medicine Perspective

ABSTRACT

Exertional rhabdomyolysis (ER) is an uncommon condition with a paucity of evidence-based guidance for diagnosis, management, and return to duty or play. Recently, a clinical practice guideline for diagnosis and management of ER in warfighters was updated by a team of military and civilian physicians and researchers using current scientific literature and decades of experience within the military population. The revision concentrated on challenging and controversial clinical questions with applicability to providers in the military and those in the greater sports medicine community. Specific topics addressed: 1) diagnostic criteria for ER; 2) clinical decision making for outpatient versus inpatient treatment; 3) optimal strategies for inpatient management; 4) discharge criteria; 5) identification and assessment of warfighters/athletes at risk for recurrent ER; 6) an appropriate rehabilitative plan; and finally, 7) key clinical questions warranting future research.

Preventive measures for the critical postexercise period in sickle cell trait and disease

The immediate postexercise/physical activity period is critical for sickle cell trait (SCT) carriers and disease (SCD) patients. Exercise-related blood acidosis is known to trigger the cascade of HbS deoxygenation and polymerization, leading to red blood cell sickling and subsequent complications. Unfortunately, two facts worsen exercise-related blood acidosis during the initial postexercise period: First, blood lactate and H⁺ concentrations continue to increase for several minutes after exercise completion, exacerbating blood acidosis. Second, blood lactate concentration remains elevated and pH altered for 20-45 min during inactivity after intense exercise, keeping acid/base balance disturbed for a long period after exercise. Therefore, the risk of complications (including vasoocclusive crises and even sudden death) persists and even worsens several minutes after intense exercise completion in SCT carriers or SCD patients. Light physical activity following intense exercise (namely, active recovery) may, by accelerating lactate removal and acid/base balance restoration, reduce the risk of complications. Scientific evidence suggests that light exercise at or below the first lactate threshold is an appropriate strategy.

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.

COVID-19 in Patients With Hematologic-Oncologic Risk Factors: Complications in Three Patients

The novel COVID-19 infection has demonstrated a spectrum of complications involving vascular, inflammatory, infectious, and metabolic conditions. These complications range from mild loss of smell to more severe acute respiratory distress syndrome (ARDS). Patients with more severe complications often require sedation and mechanical ventilation. Growing research has revealed the role of active malignancy and disease-in-remission status as possible risk factors contributing to the morbidity and mortality in COVID-19 patients. In our descriptive case series, we present three unique cases of complicated COVID-19 infection in patients with hematologic-oncologic risk factors and review the imaging features of their complications. The first patient was a 33-year-old male with sickle cell trait who developed rhabdomyolysis and myonecrosis of the paraspinal muscle in the setting of a physical fitness test; he subsequently developed an abscess at this site, presumably exacerbated by the hypoxemic state of his COVID-19 pneumonia. Our second patient was a 37-year-old male with COVID-19 pneumonia and a history of stage IV Non-Hodgkin's lymphoma in remission who developed spontaneous pneumomediastinum in the absence of positive pressure ventilation. The third COVID-positive patient was a 54-year-old male with a past medical history significant for grade 1 follicular non-Hodgkin's lymphoma in remission with sputum culture positive for mycobacterium avium complex and bronchoscopy positive for candida growth. 18-FDG/PET imaging was performed and demonstrated diffuse intense uptake throughout the lungs reflecting both the COVID-19 pneumonia and the multimicrobial superinfection.

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.

Epidemiology of Exertional Heat Illness in the Military: A Systematic Review of Observational Studies

Exertional heat illness (EHI) is an occupational hazard among military personnel. This systematic review describes the incidence, risk factors, clinical manifestations, and biomarkers of EHI in the military. Six databases from inception to 28 May 2020 were systematically reviewed using the PRISMA guidelines. Forty-one articles met the inclusion criteria and the incidence of EHI ranged from 0.2 to 10.5 per 1000 person years, while the prevalence rates ranged from 0.3% to 9.3%. Intrinsic risk factors influencing EHI were gender, physical fitness, obesity, previous history of heat illness, and motivation, while the extrinsic factors included hot environmental conditions and service unit. Evidence suggests that loss of consciousness, absence of sweating and confusion were the common clinical features of exertional heat stroke (EHS). The mean core temperature ranged from 40 to 41.6 °C, while elevated levels of creatine phosphokinase, liver enzymes, and creatinine were common biochemical markers of EHS. The findings of the review suggest a variation in the incidence of EHI among military populations possibly due to the varying definitions used. Although some risk factors of EHI were identified, more analytical studies are needed to investigate the association between EHI and other important factors such as acclimatisation and occlusive clothing.

Experience with Parent Follow-Up for Communication Outcomes after Newborn Screening Identifies Carrier Status

OBJECTIVE

To conduct interviews with a multiyear sample of parents of infants found to have heterozygous status for sickle cell hemoglobinopathy or cystic fibrosis during newborn blood screening (NBS).

STUDY DESIGN

Interviewers with clinical backgrounds telephoned parents, and followed a structured script that blended follow-up and research purposes. Recruiting followed several steps to minimize recruiting bias as much as possible for a NBS study.

RESULTS

Follow-up calls were conducted with parents of 426 infant carriers of sickle cell hemoglobinopathy, and 288 parents of cystic fibrosis carriers (34.8% and 49.6% of those eligible). Among these, 27.5% and 7.8% had no recollection of being informed of NBS results. Of those who recalled a provider explanation, 8.6% and 13.0% appraised the explanation negatively. Overall, 7.4% and 13.2% were dissatisfied with the experience of learning about the NSB result. Mean anxiety levels were low but higher in the sickle cell hemoglobinopathy group (P < .001). Misconceptions that the infant might get the disease were present in 27.5% and 7.8% of parents (despite zero actual risk for disease). Several of these data were significantly predicted by NBS result, health literacy, parental age, and race/ethnicity factors.

CONCLUSIONS

Patient-centered public health follow-up can be effective after NBS identifies carrier status. Psychosocial complications were uncommon, but harms were substantial enough to justify mitigation.

Exercise-Induced Rhabdomyolysis: A Case Report and Literature Review

A 19-year-old man presented to the ED with bilateral leg pain and dark discoloration of the urine after he started an intense aerobic exercise. Blood workup showed significantly elevated creatine kinase (CK), acute kidney injury (AKI), and disseminated intravascular coagulation (DIC). The patient had a double-incision, bilateral fasciotomy with debridement to relieve the bilateral, lower-limb, compartment syndrome following admission. Also, his kidney function deteriorated, requiring several sessions of hemodialysis. His hospital stay was complicated by multidrug-resistant (MDR) Acinetobacter baumannii bacteremia. After three weeks of hospital admission, the patient was discharged home with a follow-up outpatient physiotherapy for bilateral foot drop, which showed a remarkable recovery eventually. This case highlights the potentially life-threatening risks associated with unaccustomed physical exercise and emphasizing the essential preventive measures to reduce the risk of developing exercise-induced rhabdomyolysis. We present the pathophysiology of exercise-induced rhabdomyolysis, clinical presentation, diagnosis, treatment, and prognosis.

[Sickle cell trait complications: A case series of 6 patients]

INTRODUCTION

Patients with sickle cell trait (SCT) are commonly considered as asymptomatic carriers. However, some clinical manifestations may occur.

METHODS

Here we present a retrospective descriptive study about SCT subjects with at least one complication diagnosed in a sickle cell disease referral center, in Paris, between 2008 and 2019. We also performed a literature review on the complications of SCT subjects.

RESULTS

Six patients (between 19 and 65 years old) were included. SCT was already known only for 4 of them at the time of the complication. Four patients presented with a splenic infarct after a stay in high altitude or a plane trip, one of them was associated with papillary necrosis; one patient had isolated papillary necrosis, and the last one had splenic sequestration. These complications happened for most of them after exposure to an unusual situation of hypoxia or deshydratation. Five out of 6 patients had a marked elevated C reactive protein.

CONCLUSION

SCT may cause acute ischemic complications in a context of prolonged hypoxia or dehydration. The most commonly reported are the splenic infarct and the renal papillary necrosis. A study of hemoglobin should be considered in these clinical situations in patients with compatible ethnic origin.

Exertional Rhabdomyolysis: A Retrospective Population-based Study

PURPOSE

This study aimed to evaluate the incidence and characteristics of exertional rhabdomyolysis (ER) in a population-based cohort.

METHODS

A retrospective cohort study was performed in Olmsted County, Minnesota, from 2003 to 2015. Incident ER cases were ascertained through the Rochester Epidemiology Project medical record linkage system through electronic searches of the International Classification of Diseases, Ninth Revision, codes and clinical note text. Population incidence rate was calculated using the corresponding Rochester Epidemiology Project census populations specific to calendar year and sex. Descriptive statistics were used.

RESULTS

Of the 430 patients, 431 cases met the inclusion criteria for rhabdomyolysis; 4.9% of cases (n = 20; males n = 18; Caucasian n = 17) were ER, with one recurrence. There were no deaths secondary to ER. The age- and sex-adjusted incidence rate of ER was 1.06 ± 0.24 (95% confidence interval = 0.59-1.52) per 100,000 person-years. Endurance activity (n = 7), manual labor (n = 5), and weight lifting (n = 4) were common causes. Complications included kidney injury (n = 5), mild electrolyte abnormalities (n = 10), elevated transaminases (n = 12), and minor electrocardiographic abnormalities (n = 4). A majority of patients were hospitalized (n = 16) for a median of 2 d, had mild abnormalities in renal and liver function and electrolytes, and were discharged without sequelae.

CONCLUSION

ER in the civilian population occurs at a much lower incidence than the military population. The most common causes were endurance exercise, manual labor, and weight lifting. The majority of cases were treated conservatively with intravenous fluid resuscitation during a brief hospital stay, and all were discharged without sequela. Only one case of recurrence occurred in this cohort, indicating the recurrence rate was low.

5-(Hydroxymethyl)furfural restores low-oxygen rheology of sickle trait blood in vitro

Sickle cell trait (SCT) is the benign heterozygous carrier state for the sickle variant of the HBB gene. Most of the ~300 million people with SCT worldwide will not experience any significant complications. However, accumulating evidence finds SCT associated with increased risk for the common conditions of chronic kidney disease and venous thromboembolism, and severe but rare renal medullary carcinoma and exercise-induced rhabdomyolysis. The mechanism is uncertain, but probably involves pathological rheology of SCT blood in regions of low oxygen tension, resulting from sickle haemoglobin polymerization in SCT red cells and leading to reduced blood flow and further tissue hypoxia and damage. Here, we used an in vitro microfluidic flow system to study the oxygen-dependent rheology of SCT blood and show that 5-(hydroxymethyl)furfural, a natural breakdown product of glucose and fructose-containing foods, such as fruit juices, can reduce the effects of hypoxia on SCT blood rheology in vitro, restoring near-normal flow velocities at very low oxygen. While opinions regarding the clinical significance of the risks associated with SCT are still evolving, these results suggest that a compound present in some food may provide a potential approach for managing risks that may be associated with SCT.

Fetal Hemoglobin Modulators May Be Associated With Symptomology of Football Players with Sickle Cell Trait

OBJECTIVES

This study investigates whether genetic modifiers previously shown to influence adult fetal hemoglobin (HbF) levels and glucose-6-phosphate dehydrogenase deficiency were associated with variable symptomology in a small sample of collegiate football players with sickle cell trait.

METHODS

Survey data on self-assessed symptoms and genotype data from five single nucleotide polymorphisms (SNPs) related to HbF production and two SNPs that cause glucose-6-phosphate dehydrogenase deficiency were collected from current and former college football players.

RESULTS

In this sample, SNPs found within the β-globin gene cluster were found to be associated with a previous diagnosis of exertional sickling and experience of extreme heat during and after training. rs10189857 in the BCL11A gene was associated with body mass index and weight and with experiencing extreme thirst during and after training. No significant correlations were found between the other SNPs and symptoms within this sample.

CONCLUSIONS

These findings show that genetic variation known to affect sickle cell disease symptomology may partly explain why some football players with sickle cell trait experience adverse clinical outcomes during periods of extreme physical exertion and others do not.

The current state of sickle cell trait: implications for reproductive and genetic counseling

Sickle cell trait (SCT) is unique among the carrier states that are identified during newborn screening. Unlike other heterozygous states for rare recessive diseases, SCT is exceedingly prevalent throughout regions of the world, making sickle cell disease one of the most common monogenetic diseases worldwide. Because of this high frequency, reproductive counseling is of paramount importance. In addition, unlike other carrier states, SCT seems to be a risk factor for several clinical complications, such as extreme exertional injury, chronic kidney disease, and venous thromboembolism. Increasing knowledge about these clinical outcomes can help inform genetic counseling recommendations. Expanding research and clinical efforts are needed to ensure that the promises of modern and precision medicine can be delivered to the millions of SCT carriers and their children.

Mapping eGFR loci to the renal transcriptome and phenome in the VA Million Veteran Program

Chronic kidney disease (CKD), defined by low estimated glomerular filtration rate (eGFR), contributes to global morbidity and mortality. Here we conduct a transethnic Genome-Wide Association Study of eGFR in 280,722 participants of the Million Veteran Program (MVP), with replication in 765,289 participants from the Chronic Kidney Disease Genetics (CKDGen) Consortium. We identify 82 previously unreported variants, confirm 54 loci, and report interesting findings including association of the sickle cell allele of betaglobin among non-Hispanic blacks. Our transcriptome-wide association study of kidney function in healthy kidney tissue identifies 36 previously unreported and nine known genes, and maps gene expression to renal cell types. In a Phenome-Wide Association Study in 192,868 MVP participants using a weighted genetic score we detect associations with CKD stages and complications and kidney stones. This investigation reinterprets the genetic architecture of kidney function to identify the gene, tissue, and anatomical context of renal homeostasis and the clinical consequences of dysregulation.

Case Report: Exertional rhabdomyolysis in a spin class participant with sickle cell trait

Exertional rhabdomyolysis is more common in sickle trait due to a predisposition to dehydration and inability to concentrate the urine. Spinning, an indoor cycling workout, has been associated with exertional rhabdomyolysis in recent reports. A consequence of rhabdomyolysis is acute kidney injury, which may be expected to be more common in patients with sickle trait. We report a case of spinning induced rhabdomyolysis in a woman with sickle trait that did not result in renal injury. "Spin rhabdo" is thought to be more severe than other causes of exertional rhabdomyolysis and is associated with higher creatine kinase levels than other causes of exertional rhabdomyolysis. Therefore, individuals with known sickle trait should consider visiting their physician prior to participation in spin classes for the first time. We might also consider voluntary screening for sickle trait in at risk populations prior to enrolling in spin classes given that many patients are unaware of their sickle trait status.

An elevated creatine kinase in the context of influenza A infection and sickle cell trait

We describe the case of a 37-year-old normally fit and well man who presented to hospital with fever, lethargy and myalgia. He was found to have a creatine kinase level of over 1 million IU.l^-1. He initially underwent fluid resuscitation, but despite this his renal function declined and he required continuous veno-venous haemodiafiltration. Subsequent testing revealed a positive viral swab for influenza A and that he was a carrier of sickle cell trait. We review the literature for previous reports describing this association and demonstrate the rarity of such a presentation.