Effect of hydroxyurea in sickle cell anemia: a clinical trial in children and teenagers with severe sickle cell anemia and sickle cell beta-thalassemia

Hospitalizations among children with sickle cell disease enrolled in the Kumasi Sickle Cell Pan African Consortium (SPARCo) database: A cross sectional study

Background and Aims

Sickle cell disease (SCD) is the commonest monogenic haemolytic disorder in Africa. Despite strides made in its management, a significant proportion of patients are hospitalized from the various complications of the disease. This study set out to describe the main causes and outcomes of hospitalizations among pediatric patients with SCD.

Methods

A cross-sectional study was conducted at the Pediatric Emergency Unit of Komfo Anokye Teaching Hospital within a period of 12 months to recruit pediatric SCD patients. This study looked at causes of admission, length of hospital stay (LOS), and outcome of admission.

Results

Of the 201 SCD patients recruited, 57.2% were males and majority were of SCD-SS phenotype 83.1%. The median age was 6 years. The three leading causes of hospitalization were Vaso-occlusive pain events (VOPE) (39.8%), acute chest syndrome (ACS) (25.9%), and infections (12.4%). Ten (5.0%) of the patients presented with a stroke. High admissions were observed in June (12.4%) and November (16.9%). The median (interquartile range [IQR]) LOS was 6 days (IQR: 4-10). Six (3.0%) of the patients died from complications of the disease during hospitalization.

Conclusion

VOPE, ACS, infections, and acute anaemia from hyperhaemolysis were observed as the most common causes of admissions among SCD patients. A good outcome of discharge was seen in most of the patients that were hospitalized with a median length of stay of 6 days. This study also strengthens the importance of a good SCD database with patient follow-ups for better outcomes in SCD patients.

Computer Algorithm-Based Hydroxyurea Dosing Facilitates Titration to Maximum Tolerated Dose in Sickle Cell Anemia

Adults with sickle cell disease (SCD) experience acute and chronic complications and die prematurely. When taken at maximum tolerated dose (MTD), hydroxyurea prolongs survival; however, it has not consistently reversed organ dysfunction. Patients also frequently do not take hydroxyurea, at least in part because of physician discomfort with prescribing hydroxyurea. We sought to develop a computer program that could easily titrate hydroxyurea to MTD. This was a single-arm, open-label pilot study. Fifteen patients with homozygous SCD were enrolled in the protocol, and 10 patients were followed at baseline and then for 1 year after hydroxyurea initiation or dose titration. Fetal hemoglobin significantly increased in all 10 patients from 8.3% to 25.1% (P < .001). Nine patients were titrated to MTD in an average of 7.9 months, and the tenth patient's hydroxyurea dose was increased to 33 mg/kg/day. Computer program dosing recommendations were the same as manual dosing decisions made using the same algorithm for all patients and at all times. We also evaluated markers of cardiopulmonary, liver and renal damage. Although cardiopulmonary function did not significantly improve, direct bilirubin and alanine aminotransferase levels significantly decreased (P < .001 and P < .01, respectively). Last, although kidney function did not improve, degree of proteinuria was significantly reduced (P < .05). We have developed a computer program that reliably titrates hydroxyurea to MTD. A larger study is indicated to test the program either as a computer program or a downloadable application.

Blood rheology biomarkers in sickle cell disease

Sickle cell disease (SCD) is the most common inherited blood disorder, affecting approximately 100,000 patients in the U.S. and millions more worldwide. Patients with SCD experience a wide range of clinical complications, including frequent pain crises, stroke, and early mortality, all originating from a single-point mutation in the β-globin subunit. The RBC changes resulting from the sickle mutation lead to a host of rheological abnormalities that diminish microvascular blood flow, and produce severe anemia due to RBC hemolysis, and ischemia from vaso-occlusion initiated by sticky, rigid sickle RBCs. While the pathophysiology and mechanisms of SCD have been investigated for many years, therapies to treat the disease are limited. In addition to RBC transfusion, there are only two US Food and Drug Administration (FDA)-approved drugs to ameliorate SCD complications: hydroxyurea (HU) and L-glutamine (Endari™). The only curative therapy currently available is allogeneic hematopoietic stem cell transplantation (HSCT), which is generally reserved for individuals with a matched related donor, comprising only 10–15% of the total SCD population. Potentially curative advanced gene therapy approaches for SCD are under investigation in ongoing clinical trials. The ultimate goal of any curative treatment should be to repair the hemorheological abnormalities caused by SCD, and thus normalize blood flow and prevent clinical complications. Our mini-review highlights a set of key hemorheological biomarkers (and the current and emerging technologies used to measure them) that may be used to guide the development of novel curative and palliative therapies for SCD, and functionally assess outcomes.

Impact statement

Severe impairment of blood rheology is the hallmark of SCD pathophysiology, and one of the key factors predisposing SCD patients to pain crises, organ damage, and early mortality. As novel therapies emerge to treat or cure SCD, it is crucial that these treatments are functionally evaluated for their effect on blood rheology. This review describes a comprehensive panel of rheological biomarkers, their clinical uses, and the technologies used to obtain them. The described technologies can produce highly sensitive measurements of the ability of current treatments to improve blood rheology of SCD patients. The goal of curative therapies should be to achieve blood rheology biomarkers measurements in the range of sickle cell trait individuals (HbAS). The use of the panel of rheological biomarkers proposed in this review could significantly accelerate the development, optimization, and clinical translation of novel therapies for SCD.

Hydroxycarbamine: from an Old Drug Used in Malignant Hemopathies to a Current Standard in Sickle Cell Disease

While hydroxycarbamide (hydroxyurea, HU) has less and fewer indications in malignant hemopathies, it represents the only widely used drug which modifies sickle cell disease pathogenesis. Clinical experience with HU for patients with sickle cell disease has been accumulated over the past 25 years in Western countries. The review of the literature provides increasing support for safety and efficacy in both children and adults for reducing acute vaso-occlusive events including pain episodes and acute chest syndrome. No increased incidence of leukemia and teratogenicity was demonstrated. HU has become the standard-of-care for sickle cell anemia but remains underused. Barriers to its use should be identified and overcome.

Changes in coping, pain, and activity after cognitive-behavioral training: a randomized clinical trial for pediatric sickle cell disease using smartphones

OBJECTIVES

We examined the outcomes of a cognitive-behavioral therapy (CBT) intervention for pain in pediatric sickle cell disease (SCD) using smartphones as a novel delivery method.

MATERIALS AND METHODS

Forty-six children with SCD received CBT coping skills training using a randomized, waitlist control design. The intervention involved a single session of CBT training and home-based practice using smartphones for 8 weeks. Pre-post questionnaires between the randomized groups were used to evaluate changes in active psychological coping and negative thinking using the Coping Strategies Questionnaire. Daily diaries completed by the full sample during the treatment period were used to assess whether CBT skill use was related to reductions in next-day pain intensity and increases in same-day functional activity.

RESULTS

The pre-post group comparison suggested that the youth increased active psychological coping attempts with the intervention. Daily diary data indicated that when children used CBT skills on days with higher pain, there were reductions in next-day pain intensity. There was no such association between skill use and functional activity.

DISCUSSION

CBT coping skills training supported using smartphones can increase coping and reduce pain intensity for children with SCD; however, additions to the study protocols are recommended in future studies. Advantages and caveats of using smartphones are also discussed.

Increased risk of severe vaso-occlusive episodes after initial acute chest syndrome in children with sickle cell anemia less than 4 years old: Sleep and asthma cohort

Previous studies have shown that the highest incidence of acute chest syndrome (ACS) in sickle cell disease occurs in children <4 years old, and a history of ACS at this age is a risk factor for future ACS episodes. However, the interval associated with the highest risk of subsequent ACS or severe pain is not known. Through this mixed retrospective-prospective observational study, the Sleep and Asthma Cohort, we sought to determine the interval after an initial ACS episode during which the majority of children <4 years old are rehospitalized for ACS or severe pain. The cumulative prevalence of rehospitalization for ACS or severe pain within 6 months, 1 years, and 2 years was calculated for children with an initial ACS episode <4 years old and compared to children with an initial ACS episode ≥4 years old. A total of 44.8% and 55.2% of participants had an initial ACS episode <4 years and ≥4 years old (Range: 4-17.7 years), respectively. At 1 year following the initial ACS episode, children <4 years old had a significantly higher cumulative prevalence of rehospitalizations for ACS or pain as compared to children ≥4 years of age, 62.5 and 39.1%, respectively (P = 0.009). After initial ACS episodes, the majority of children <4 years old will be rehospitalized for ACS or severe pain within one year, suggesting the need for a therapeutic intervention for this high-risk group.

Meta-analysis on effectiveness of hydroxyurea to treat transfusion-dependent beta-thalassemia

Objective To determine the efficacy of hydroxyurea therapy on transfusion-dependent beta-thalassemia patients. Methods This study collected articles from databases, applied inclusion and exclusion criteria, and analyzed them for bias. The effects of hydroxyurea on transfusion requirements were categorized according to the following definitions. 'Good responders' were participants who became transfusion independent after treatment. 'Moderate responders' were participants who were still transfusion dependent, however, experienced a significant decline in their transfusion requirements. 'Poor responders' were defined as participants who did not respond to hydroxyurea. Results A total of 13 studies met all the inclusion and exclusion criteria providing a total of 1196 study participants. The weighted average of the odds ratio using the random effect model (P < 0.001) was determined to be 0.493 for good responders, 0.270 for moderate responders, and 0.229 for poor responders. Discussion Until now, there has not been any double-blinded placebo-controlled studies performed looking at the effectiveness of hydroxyurea with this regard, and this substantially limits this meta-analysis. More studies should be conducted to determine whether hydroxyurea preferentially treats particular type of mutations over others. Conclusion This study suggests that hydroxyurea provides some benefit to patients, and therefore, in certain clinical situations, it may be understandable to start a trial therapy of hydroxyurea to qualifying patients. However, a double-blinded placebo-controlled studies should be performed before its efficacy can be considered established.

Does hydroxyurea prevent pulmonary complications of sickle cell disease?

A 27-year-old man with sickle cell disease (HbSS) presents to the sickle cell clinic for follow-up after a screening echocardiogram revealed an increased tricuspid regurgitant velocity of 2.7 m/s. He has a history of 2 painful crises per year and has been hospitalized 3 times over the past 10 years for management of painful crises. He had one episode of acute chest syndrome at age 15 that was treated with an RBC exchange transfusion, supplemental oxygen, and intravenous antibiotics; he did not require mechanical ventilation. He has not had additional episodes of acute chest syndrome and does not have a history of stroke, retinopathy, or leg ulcers. The patient has never been treated with hydroxyurea. He wants to know whether hydroxyurea will prevent future pulmonary complications related to sickle cell disease.

Sickle cell disease: management options and challenges in developing countries

Sickle Cell Disease (SCD) is the most common genetic disorder of haemoglobin in sub-Saharan Africa. This commentary focuses on the management options available and the challenges that health care professionals in developing countries face in caring for patients with SCD. In a developing countries like Ghana, new-born screening is now about to be implemented on a national scale. Common and important morbidities associated with SCD are vaso-occlusive episodes, infections, Acute Chest Syndrome (ACS), Stroke and hip necrosis. Approaches to the management of these morbidities are far advanced in the developed countries. The differences in setting and resource limitations in developing countries bring challenges that have a major influence in management options in developing countries. Obviously clinicians in developing countries face challenges in managing SCD patients. However understanding the disease, its progression, and instituting the appropriate preventive methods are paramount in its management. Emphasis should be placed on early counselling, new-born screening, anti-microbial prophylaxis, vaccination against infections, and training of healthcare workers, patients and caregivers. These interventions are affordable in developing countries.

Clinical experience with fetal hemoglobin induction therapy in patients with β-thalassemia

Recent molecular studies of fetal hemoglobin (HbF) regulation have reinvigorated the field and shown promise for the development of clinical HbF inducers to be used in patients with β-thalassemia and sickle cell disease. However, while numerous promising inducers of HbF have been studied in the past in β-thalassemia patient populations, with limited success in some cases, no universally effective agents have been found. Here we examine the clinical studies of such inducers in an attempt to systematically review the field. We examine trials of agents, including 5-azacytidine, hydroxyurea, and short-chain fatty acids. This review highlights the heterogeneity of clinical studies done on these agents, including both the patient populations examined and the study end points. By examining the published studies of these agents, we hope to provide a resource that will be valuable for the design of future studies of HbF inducers in β-thalassemia patient populations.

Hematological differences between patients with different subtypes of sickle cell disease on hydroxyurea treatment

OBJECTIVE

Sickle cell anemia and the interaction S/Beta thalassemia differ in hematological values due to microcytosis and hypochromia caused by the thalassemic mutation. The clinical benefit of long-term hydroxyurea treatment is undeniable in sickle cell disease with monitoring of the biological action of the drug being by the complete blood count. The objective of this work is to compare changes in some of the erythrocytic indexes between S/Beta thalassemia and sickle cell anemia patients on long-term hydroxyurea treatment.

METHODS

The values of erythrocyte indexes (mean corpuscular volume and mean corpuscular hemoglobin) were compared in a retrospective study of two groups of patients (Sickle cell anemia and S/Beta thalassemia) on hydroxyurea treatment over a mean of six years.

RESULTS

The quantitative values of the two parameters differed between the groups. Increases in mean corpuscular volume and reductions in mean corpuscular hemoglobin delay longer in S/Beta thalassemia patients (p-value = 0.018).

CONCLUSION

Hematological changes are some of the beneficial effects of hydroxyurea in sickle cell disease as cellular hydration increases and the hemoglobin S concentration is reduced. The complete blood count is the best test to monitor changes, but the interpretation of the results in S/Beta thalassemia should be different.

Decision analysis of treatment strategies in children with severe sickle cell disease

We designed a decision analysis model comparing 4 treatment strategies for severe sickle cell disease: no intervention, hydroxyurea (HU), chronic transfusion, or stem cell transplant (SCT). The treatment strategy associated with the highest average utility (quality of life) was SCT (0.85). Average utilities for no treatment, chronic transfusion, and HU were 0.68, 0.71, and 0.80, respectively. Our model was quite sensitive to quality-of-life estimates, indicating that a true comparison of HU and transplantation cannot occur until investigators directly measure the health-related quality of life in children with sickle cell disease during HU therapy and after SCT.

Clinical and Laboratory Effects of Hydroxyurea in Children and Adolescents with Sickle Cell Anemia: A Portuguese Hospital Study

Our aim was to assess the efficacy and safety of hydroxyurea (HU) in children with severe forms of sickle cell anemia followed in a Portuguese hospital. We carried out an open-label uncontrolled prospective study, which included children with severe forms of sickle cell anemia. Hydroxyurea was started at 15 mg/kg/day and increased to a maximum dose of 25 mg/kg/day. Patients were monitored to assess compliance, clinical and hematological response and toxicity. Nine children and adolescents, five girls and four boys, with a median age of 13 years (range 8 to 16) were enrolled in the study during a period of 24 months. All patients completed at least 15 months of therapy. Hb F was significantly increased, from a mean of 7.0 +/- 3.9% to 13.7 +/- 5.3% (p = 0.028). Clinically, all patients responded significantly with a reduction of 80% in the number of vaso-occlusive crises (VOC), 69% in hospital admissions, 76% in hospitalization days and 67% in transfusion requirements, without significant toxicity. We concluded that, in our population, HU proved to be effective in increasing Hb F levels, and in decreasing hospitalizations for VOC and transfusion requirements with no major side effects. Long-term clinical follow-up is important to certify benefit maintenance.

Length of treatment and dose as determinants of mutagenicity in sickle cell disease patients treated with hydroxyurea

Hydroxyurea (HU) is an antineoplastic drug widely used in the clinical management of patients with sickle cell disease (SCD), and many questions related with its use remain unresolved. Given the severity of SCD, HU benefits, although not thoroughly confirmed, seem to outweigh its potential carcinogenicity. This study aimed to assess the genotoxicity associated with HU dose and treatment length by evaluating mutagenicity in patients with SCD treated with HU (SCHU) using the cytokinesis-block micronucleus assay (CBMN) in white cells. The study was conducted with 35 individuals in the SCHU group and 34 controls matched according to age, sex and smoking habit. CBMN results showed an increase (p=0.032) in the number of micronuclei (MN), but not of nucleoplasmic bridges (NPB) or nuclear buds (NBUD) in the SCHU group. The increased frequency of MN in the SCHU group was significantly correlated with treatment length and final HU dose, which confirms that patients with SCD treated with HU should be carefully monitored to reduce the risk of carcinogenicity.

Use of handheld wireless technology for a home-based sickle cell pain management protocol

PURPOSE

To evaluate use of a handheld electronic wireless device to implement a pain management protocol for participants with sickle cell disease (SCD).

METHODS

Participants were 19 patients with SCD aged 9-20 who experienced vaso-occlusive pain. A single-session training on the use of cognitive-behavioral coping skills was followed by instruction on how to practice these skills and monitor daily pain experience using the device. Daily pain experience and practice of coping skills were collected for the 8-week intervention period using wireless technology.

RESULTS

High rates of participation, daily diary completion and consumer satisfaction support the use of handheld wireless devices to implement this protocol. A comparison of the rates of self and device-recorded skills practice provides important information about the use of electronic monitoring for behavioral interventions.

CONCLUSION

Wireless data transfer technology has significant potential to become a practical method to improve symptom monitoring and communication between patients and providers.

Response to hydroxyurea therapy in beta-thalassemia

Although a relatively small number of previous studies suggest a modest response to hydroxyurea (HU) therapy in beta-thalassemia, more recent investigations have revealed that some transfusion-dependent patients can become transfusion-independent following HU therapy. Patients with Ggamma XmnI polymorphism, several beta-globin mutations, and alpha-thalassemia deletions were inconsistently reported to have significant responses to HU therapy. To better predict who may respond, we retrospectively evaluated the clinical response and the molecular background of 18 beta-thalassemia patients treated with HU for a mean of 46 months. The majority of transfusion-dependent patients responded to HU therapy with 9 out of 11 (82%) becoming transfusion-independent. Five thalassemia intermedia (TI) patients receiving occasional blood transfusion did not require any additional transfusions following therapy and two TI patients who had never received transfusions had a 2 g/dl increase in their hemoglobin level. The majority of beta-thalassemia major patients who became transfusion-independent (7/9) were either homozygous (5) or heterozygous (2) for the XmnI polymorphism. No correlation was identified between response to therapy and the presence of specific beta-thalassemia mutations or alpha-globin deletions. We conclude that further analysis of the degree of response of transfusion-dependent beta-thalassemia patients to HU therapy, as well as, the impact of their genetic background on this response is required to identify patients likely to have significant response.

DNA damage in blood leukocytes of individuals with sickle cell disease treated with hydroxyurea

Hydroxyurea (HU) plays an important role in the treatment of patients with sickle cell disease (SCD). Although HU has been associated with an increased risk of leukemia in some patients with myeloproliferative disorders, the mutagenic and carcinogenic potential of HU has not been established. This study investigated levels of DNA damage using the alkaline (pH>13) comet assay to analyze peripheral blood leukocytes sampled from 28 patients with SCD treated with HU (SCHU) and from 28 normal individuals. The damage index (DI) in the SCHU group was significantly higher than in controls (p<0.05). Gender, smoking or age were not associated with DNA damage in controls or SCHU individuals. In the group of SCHU individuals, mean HU dose and DI were positively correlated, and individuals who received a mean dose of >20 mg/kg HU (DI=24.9+/-5.5) showed significantly more DNA damage than those who received < or =20 mg/kg HU (DI=14.6+/-1.8) (p<0.05). Individuals treated for > or =42 months (DI=23.1+/-4.2) showed significantly greater DNA damage than those treated for <42 months (13.6+/-1.9) (p<0.05). DI was inversely correlated with body mass index in the SCHU group.

Sickle cell disease: role of reactive oxygen and nitrogen metabolites

1. Sickle cell disease (SCD) is an inherited disorder of haemoglobin synthesis that is associated with significant morbidity and mortality due to sequelae of episodic vaso-occlusive events: pain crises and multiorgan damage. The microvascular responses to the initiation, progression and resolution of vaso-occlusive events are consistent with an inflammatory phenotype as suggested by activation of multiple cell types, an oxidatively stressed environment and endothelial cell dysfunction. 2. Decreased anti-oxidant defences in SCD patients and mice are accompanied by activation of enzymatic (NADPH oxidase, xanthine oxidase) and non-enzymatic (sickle haemoglobin auto-oxidation) sources of reactive oxygen species. The resultant oxidative stress leads to dysfunction/activation of arteriolar and venular endothelial cells, resulting in impaired vasomotor function and blood cell-endothelial cell adhesion. 3. Changes in substrate and cofactor availability for endothelial cell nitric oxide synthase may underlie reactive oxygen- and nitrogen-induced events that contribute to SCD-induced vasculopathy. 4. The emerging role of reactive oxygen and nitrogen species in the pathogenesis of SCD provides a platform for the development of novel agents to treat this painful and lethal disease.

Asthma is associated with acute chest syndrome and pain in children with sickle cell anemia

Pain and acute chest syndrome (ACS) episodes are 2 of the most common causes of hospitalization in children with sickle cell anemia (SCA). However, very few potentially modifiable risk factors for either condition have been identified. In this prospective infant cohort study, we tested the hypothesis that asthma is associated with an increased incidence rate of pain and ACS episodes. An infant cohort was composed of 291 African American children with hemoglobin SS enrolled in the Cooperative Study for Sickle Cell Disease before age 6 months and followed beyond age 5 years. Asthma was defined by a physician diagnosis, an acute asthma event, or use of prescription asthma medications. The incidence rates of ACS and painful episodes were compared for children with and without asthma. A clinical diagnosis of asthma was made in 17% of the cohort. Asthma was associated with more frequent ACS episodes (0.39 vs 0.20 events per patient year, P < .001) and painful episodes (1.39 vs 0.47 events per patient year, P < .001). In conclusion, in children with SCA, asthma is associated with an increased incidence of sickle cell disease-related morbidity, including ACS and painful episodes.

Parents' assessment of risk in sickle cell disease treatment with hydroxyurea

Hydroxyurea is the only medication shown to reduce the severity of sickle cell disease (SCD), but its long-term risks are unknown. Families of 58 children with SCD were interviewed on their perception of the potential risks of hydroxyurea treatment, and whether disease severity was a major factor in their treatment decision. Parents rated the severity of their child's SCD (86% as severe, 26% moderate, and 47% mild) and then the highest levels of risk that they would tolerate for both potential cancer (range 1/1,000 to 1/2) and potential birth defects (range 1/1,000 to 1/3) to benefit their child with hypothetical hydroxyurea treatment. Parents of 29 of the 58 children were unwilling to take any cancer risk whatsoever as a potential side effect of treatment, and 29 of 58 (not all the same parents) were unwilling to take any risk for birth defects, including half the children with severe SCD. For those families who did accept some risk, higher acceptable risk correlated with higher disease severity in the child (P = 0.04). The study's mixed findings highlight the complexities of risk perception and suggest that future studies of risks and benefits from the parental viewpoint are needed as candidate therapies are developed for SCD.

Long-term hydroxyurea therapy for infants with sickle cell anemia: the HUSOFT extension study

The long-term efficacy and toxicity of hydroxyurea for infants are undefined, and its role in preventing organ dysfunction is unknown. Short-term feasibility of hydroxyurea administration, toxicities, hematologic effects, and effect on spleen function in infants with sickle cell anemia (SCA) were reported (Hydroxyurea Safety and Organ Toxicity [HUSOFT] trial). These infants completing 2 years of hydroxyurea therapy (20 mg/kg/d) were offered study extension with dose escalation to 30 mg/kg/d. Patients were monitored with laboratory tests and biannual imaging studies. Hematologic indices were compared with predicted age-specific values and event rates compared with historic rates. All 21 subjects completing the original trial enrolled in the extension study: median age, 3.4 years old (range, 2.6 to 4.4 years); 12 females; 20 with Hb SS, 1 with Hb S/beta0-thalassemia. Seventeen patients completed 4 years of hydroxyurea, and 11 completed 6 years. After 4 years, hydroxyurea was associated with increased hemoglobin concentration, percentage of fetal hemoglobin (Hb F), and mean corpuscular volume (MCV) and decreased reticulocytes, white blood cells (WBCs), and platelets (P < .01). Patients experienced 7.5 acute chest syndrome (ACS) events per 100 person-years, compared with 24.5 events per 100 person-years among historic controls (P = .001). Treated patients had better spleen function than expected and improved growth rates. Infants with SCA tolerate prolonged hydroxyurea therapy with sustained hematologic benefits, fewer ACS events, improved growth, and possibly preserved organ function.

The role of hydroxyurea in the management of sickle cell disease

Sickle cell disease (SCD) is one of the most common genetic diseases with some 250,000 new births each year. Most patients suffer intermittent pain crises and life-threatening events while life expectancy is considerably reduced. Until the last decade management was purely preventative or supportive aimed at symptom control. Apart from stem cell transplant, there is no cure but the oral chemotherapeutic drug hydroxyurea (HU) has now established a role in ameliorating the disease and improving life expectancy for most patients. There are side effects and risks of HU treatment in SCD but for moderate and severely affected patients, the benefits can be significant.

Sickle cell anemia in the pediatric intensive care unit: novel approaches for managing life-threatening complications

Although the manifestations of sickle cell disease (SCD) do not typically necessitate critical care management, several life-threatening complications may require admission to the pediatric intensive care unit. Children with SCD are at risk for serious complications such as vaso-occlusive pain crises, cerebral vascular accidents, acute chest syndrome, severe anemia related to aplastic and splenic sequestration crises, infection, and multiorgan failure. Despite years of study, little progress has been made in understanding the pathophysiology of SCD. For this reason, management has been primarily focused on treating the negative sequelae of the disease. However, exciting ongoing research has led to great improvements not only in the understanding of the disease, but also in what was once considered routine therapy for SCD. Research on the use of modalities such as inhaled nitric oxide, L-arginine therapy, and transcranial Doppler ultrasound, and the development of blood transfusion programs are making strides in reducing morbidity and mortality, and in improving the quality of life for children with SCD. Perhaps most exciting are the advances in bone marrow and stem cell transplantation, which offer hope of an eventual cure for this debilitating and deadly disease. Advanced practice nurses play a pivotal role in coordinating care for these critically ill children. Knowledge of both current and investigational therapies allows the advanced practice nurse to provide comprehensive, state-of-the-art care to children with life-threatening complications of SCD.

Treatment of sickle cell pain

Sickle cell disease affects 70,000 Americans who experience an average of 0.8 painful episodes each year. The pathophysiology of sickle cell pain is not completely understood. The disease is characterized by both acute and chronic pain syndromes. Patients with sickle cell pain often encounter barriers to receiving appropriate care, including lack of continuity of care and perceived opiate addiction. Studies describing pharmacotherapy for sickle cell pain have been primarily retrospective and uncontrolled. In analyzing the available literature regarding pathophysiology, assessment, and treatment of sickle cell pain, we found a need for increased practitioner education and intervention to improve the level of care provided to patients with this disease.

Pharmacological induction of fetal hemoglobin in sickle cell disease and beta-thalassemia

A number of pharmacological agents are currently available for the induction of fetal hemoglobin (HbF) in patients with sickle cell disease and beta-thalassemia. Here we review the development of this new class of therapeutics and summarize the clinical trials that investigate their efficacy in patients with hemoglobin disorders. Hydroxyurea is the first of these drugs to be approved by the Food and Drug Administration for the treatment of sickle cell disease. Currently, the major focus is the development of safer agents and combinations of drugs that can increase HbF to levels high enough to prevent all complications of the disease. Progress in adapting the same strategy to the treatment of thalassemic disorders has been much slower. Although all the agents that are effective in sickle cell disease have similar HbF-inducing activity in beta-thalassemia, their use has rarely resulted in significant amelioration of the anemia. More research and more effective agents will be needed to make a significant impact on thalassemia. Nonetheless, success in this relatively young field has been very gratifying; before the end of this decade, clinically meaningful induction of HbF may become an achievable goal in most patients with hemoglobin disorders.

Sickle cell anemia

Sickle cell anemia (SCA) is a disease caused by production of abnormal hemoglobin, which binds with other abnormal hemoglobin molecules within the red blood cell to cause rigid deformation of the cell. This deformation impairs the ability of the cell to pass through small vascular channels; sludging and congestion of vascular beds may result, followed by tissue ischemia and infarction. Infarction is common throughout the body in the patient with SCA, and it is responsible for the earliest clinical manifestation, the acute pain crisis, which is thought to result from marrow infarction. Over time, such insults result in medullary bone infarcts and epiphyseal osteonecrosis. In the brain, white matter and gray matter infarcts are seen, causing cognitive impairment and functional neurologic deficits. The lungs are also commonly affected, with infarcts, emboli (from marrow infarcts and fat necrosis), and a markedly increased propensity for pneumonia. The liver, spleen, and kidney may experience infarction as well. An unusual but life-threatening complication of SCA is sequestration syndrome, wherein a considerable amount of the intravascular volume is sequestered in an organ (usually the spleen), causing vascular collapse; its pathogenesis is unknown. Finally, because the red blood cells are abnormal, they are removed from the circulation, resulting in a hemolytic anemia. For the patient with SCA, however, the ischemic complications of the disease far outweigh the anemia in clinical importance.