Outcome in hemoglobin SC disease: a four-decade observational study of clinical, hematologic, and genetic factors

Terminology for Retinal Findings in Sickle Cell Disease Research: A Scoping Review

OBJECTIVE

To review the current sickle cell disease (SCD) literature to assess how "retinopathy" has been defined and to identify ocular outcomes that have been measured and described.

DESIGN

A systematic scoping review of SCD literature was completed regarding ocular manifestations of SCD and vision outcomes across all medical specialties.

SUBJECTS

Participants with SCD and control patients were included in our data extraction.

METHODS

We reviewed English-language literature from 2000 to 2021 for eligible studies by searching PubMed, Google Scholar, Embase, and the Cochrane library using terms to encompass SCD and ocular findings.

MAIN OUTCOME MEASURES

Data collection included study information, patient characteristics, vision-related findings (inclusion criteria and/or study outcomes), and retinopathy characteristics (definition, when, how and by whom diagnosed).

RESULTS

We identified 4006 unique citations and 111 were included in the analysis. Ophthalmologists were senior authors of about half (59/111; 53.2%) of the articles; most articles were published between 2016 and 2021 (71/111; 70.0%). The studies had been conducted primarily in North America (54/111; 48.6%) or Europe (23/111; 20.7%); designs were cross-sectional (51/111; 45.9%), prospective cohort (28/111; 25.2%), retrospective cohort (27/111; 24.3%), and case-control (4/111; 3.6%). Among studies reporting any retinopathy, it was commonly defined as a combination of nonproliferative sickle cell retinopathy and proliferative sickle cell retinopathy (PSR; 52/87; 59.8%), infrequently as PSR only (6/87; 6.9%), or not defined at all (23/87; 26.4%). The Goldberg classification was used to grade retinopathy in almost half of the studies (41/87; 47.1%). Investigators reporting diagnostic methods used clinical fundus examination (56/111; 50.4%), OCT (24/111; 21.6%), fluorescein angiography (20/111; 18.0%), ultrawidefield fundus photographs (15/111; 13.5%), and OCT angiography (10/111; 9.0%), or did not report methods (28/111; 25.2%).

CONCLUSIONS

There are inconsistencies in documentation of methods and outcomes in studies of SCD ophthalmic findings. Particularly concerning is the lack of documentation of ophthalmic examination methods, qualifications of examiners, and clarity and specificity of sickle cell retinopathy definitions. With the increase in SCD treatment research and novel systemic therapies available, it is important to adopt clear and consistent descriptions and rigorous data collection and reporting of ophthalmic outcomes in SCD studies.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Prospective identification of variables as outcomes for treatment (PIVOT): study protocol for a randomised, placebo-controlled trial of hydroxyurea for Ghanaian children and adults with haemoglobin SC disease

BACKGROUND

Haemoglobin SC (HbSC) is a common form of sickle cell disease (SCD), especially among individuals of West African ancestry. Persons with HbSC disease suffer from the same clinical complications and reduced quality of life that affect those with sickle cell anaemia (HbSS/Sβ0). Retrospective anecdotal data suggest short-term safety and benefits of hydroxyurea for treating HbSC, yet rigorous prospective data are lacking regarding optimal dosing, clinical and laboratory effects, long-term safety and benefits, and appropriate endpoints to monitor. Prospective Investigation of Variables as Outcomes for Treatment (PIVOT) was designed with three aims: (1) to measure the toxicities of hydroxyurea treatment on laboratory parameters, (2) to assess the effects of hydroxyurea treatment on sickle-related clinical and laboratory parameters, and (3) to identify study endpoints suitable for a future definitive phase III trial of hydroxyurea treatment of HbSC disease.

METHODS

PIVOT is a randomised, placebo-controlled, double blind clinical trial of hydroxyurea. Approximately 120 children and 120 adults ages 5-50 years with HbSC disease will be enrolled, screened for 2 months, and then randomised 1:1 to once-daily oral hydroxyurea or placebo. Study treatment will be prescribed initially at 20 ± 5 mg/kg/day with an opportunity to escalate the dose twice over the first 6 months. After 12 months of blinded study treatment, all participants will be offered open-label hydroxyurea for up to 4 years. Safety outcomes include treatment-related cytopenias, whole blood viscosity, and adverse events. Efficacy outcomes include a variety of laboratory and clinical parameters over the first 12 months of randomised treatment, including changes in haemoglobin and fetal haemoglobin, intracranial arterial velocities measured by transcranial Doppler ultrasound, cerebral oxygenation using near infrared spectrometry, spleen volume and kidney size by ultrasound, proteinuria, and retinal imaging. Exploratory outcomes include functional erythrocyte analyses with ektacytometry for red blood cell deformability and point-of-sickling, patient-reported outcomes using the PROMIS questionnaire, and 6-min walk test.

DISCUSSION

For children and adults with HbSC disease, PIVOT will determine the safety of hydroxyurea and identify measurable changes in laboratory and clinical parameters, suitable for future prospective testing in a definitive multi-centre phase III clinical trial.

TRIAL REGISTRATION

PACTR, PACTR202108893981080. Registered 24 August 2021, https://pactr.samrc.ac.za.

The pleiotropic effects of α-thalassemia on HbSS and HbSC sickle cell disease: Reduced erythrocyte cation co-transport activity, serum erythropoietin, and transfusion burden, do not translate into increased survival

α-Thalassemia is one of the most important genetic modulators of sickle cell disease (SCD). Both beneficial and detrimental effects have been described previously. We use a 12-year data set on a large cohort of patients with HbSS (n = 411) and HbSC (n = 146) to examine a wide range of these clinical and laboratory associations. Our novel findings are that α-thalassemia strongly reduces erythrocyte potassium chloride co-transporter (KCC) activity in both HbSS and HbSC (p = .035 and p = .00045 respectively), suggesting a novel mechanism through which α-thalassemia induces a milder phenotype by reducing red cell cation loss. This may be particularly important in HbSC where reduction in mean cell hemoglobin concentration is not seen and where KCC activity has previously been found to correlate with disease severity. Additionally, we show that α-thalassemia not only increases hemoglobin in patients with HbSS (p = .0009) but also reduces erythropoietin values (p = .0005), demonstrating a measurable response to improved tissue oxygenation. We confirm the reno-protective effect of α-thalassemia in patients with HbSS, with reduced proteinuria (p = .003) and demonstrate a novel association with increased serum sodium (p = .0004) and reduced serum potassium values (p = 5.74 × 10^-10 ). We found patients with α-thalassemia had a reduced annualized transfusion burden in both HbSS and HbSC, but α-thalassemia had no impact on annualized admission rates in either group. Finally, in a larger cohort, we report a median survival of 62 years in patients with HbSS (n = 899) and 80 years in those with HbSC (n = 240). α-thalassemia did not influence survival in HbSS, but a nonsignificant trend was seen in those with HbSC.

Determinants of severity in sickle cell disease

Sickle cell disease is a very variable condition, with outcomes ranging from death in childhood to living relatively symptom free into the 8^th decade. Much of this variability is unexplained. The co-inheritance of α thalassaemia and factors determining HbF levels significantly modify the phenotype, but few other significant genetic variants have been identified, despite extensive studies. Environmental factors are undoubtedly important, with socio-economics and access to basic medical care explaining the huge differences in outcomes between many low- and high-income countries. Exposure to cold and windy weather seems to precipitate acute complications in many people, although these effects are unpredictable and vary with geography. Many studies have tried to identify prognostic factors which can be used to predict outcomes, particularly when applied in infancy. Overall, low haemoglobin, low haemoglobin F percentage and high reticulocytes in childhood are associated with worse outcomes, although again these effects are fairly weak and inconsistent.

Variations and characteristics of the various clinical phenotypes in a cohort of Nigerian sickle cell patients

BACKGROUND

Sickle cell anaemia affects about 4 million people across the globe, making it an inherited disorder of public health importance. Red cell lysis consequent upon haemoglobin crystallization and repeated sickling leads to anaemia and a baseline strain on haemopoiesis. Vaso-occlusion and haemolysis underlies majority of the chronic complications of sickle cell. We evaluated the clinical and laboratory features observed across the various clinical phenotypes in adult sickle cell disease patients.

METHODS

Steady state data collected prospectively in a cohort of adult sickle cell disease patients as out-patients between July 2010 and July 2020. The information included epidemiological, clinical and laboratory data.

RESULTS

About 270 patients were captured in this study (165 males and 105 females). Their ages ranged from 16 to 55 years, with a median age of 25 years. Sixty-eight had leg ulcers, 43 of the males had priapism (erectile dysfunction in 8), 42 had AVN, 31 had nephropathy, 23 had osteomyelitis, 15 had osteoarthritis, 12 had cholelithiasis, 10 had stroke or other neurological impairment, 5 had pulmonary hypertension, while 23 had other complications. Frequency of crisis ranged from 0 to >10/year median of 2. Of the 219 recorded, 148 of the patients had been transfused in the past, while 71 had not.

CONCLUSION

The prevalence of SLU, AVN, priapism, nephropathy and the other complications of SCD show some variations from other studies. This variation in the clinical parameters across different clinical phenotypes indicates an interplay between age, genetic and environmental factors.

Alpha thalassemia, but not βS-globin haplotypes, influence sickle cell anemia clinical outcome in a large, single-center Brazilian cohort

Alpha thalassemia and beta-globin haplotype are considered classical genetic disease modifiers in sickle cell anemia (SCA) causing clinical heterogeneity. Nevertheless, their functional impact on SCA disease emergence and progression remains elusive. To better understand the role of alpha thalassemia and beta-globin haplotype in SCA, we performed a retrospective study evaluating the clinical manifestations of 614 patients. The univariate analysis showed that the presence of alpha-thalassemia -3.7-kb mutation (αα/-α and -α/-α) decreased the risk of stroke development (p = 0.046), priapism (p = 0.033), and cholelithiasis (p = 0.021). Furthermore, the cumulative incidence of stroke (p = 0.023) and cholelithiasis (p = 0.006) was also significantly lower for patients carrying the alpha thalassemia -3.7-kb mutation. No clinical effects were associated with the beta-globin haplotype analysis, which could be explained by the relatively homogeneous haplotype composition in our cohort. Our results reinforce that alpha thalassemia can provide protective functions against hemolysis-related symptoms in SCA. Although, several genetic modifiers can impact the inflammatory state of SCA patients, the alpha thalassemia mutation remains one of the most recurrent genetic aberration and should therefore always be considered first.

Gene therapy for sickle cell disease

BACKGROUND

Sickle cell disease encompasses a group of genetic disorders characterized by the presence of at least one hemoglobin S (Hb S) allele, and a second abnormal allele that could allow abnormal haemoglobin polymerisation leading to a symptomatic disorder. Autosomal recessive disorders (such as sickle cell disease) are good candidates for gene therapy because a normal phenotype can be restored in diseased cells with only a single normal copy of the mutant gene. This is an update of a previously published Cochrane Review.

OBJECTIVES

The objectives of this review are: - to determine whether gene therapy can improve survival and prevent symptoms and complications associated with sickle cell disease; - to examine the risks of gene therapy against the potential long-term gain for people with sickle cell disease.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, which comprises of references identified from comprehensive electronic database searches and searching relevant journals and abstract books of conference proceedings. We also searched online trial registries, Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 21 September 2020.

SELECTION CRITERIA

All randomised or quasi-randomised clinical trials (including any relevant phase 1, 2 or 3 trials) of gene therapy for all individuals with sickle cell disease, regardless of age or setting.

DATA COLLECTION AND ANALYSIS

No trials of gene therapy for sickle cell disease were found.

MAIN RESULTS

No trials of gene therapy for sickle cell disease were reported.

AUTHORS' CONCLUSIONS

No randomised or quasi-randomised clinical trials of gene therapy for sickle cell disease were reported. Thus, no objective conclusions or recommendations in practice can be made on gene therapy for sickle cell disease. This systematic review has identified the need for well-designed, randomised controlled trials to assess the benefits and risks of gene therapy for sickle cell disease.

Hb S/-Thalassemia in the REDS-III Brazil Sickle Cell Disease Cohort: Clinical, Laboratory and Molecular Characteristics

We described the clinical, laboratory and molecular characteristics of individuals with Hb S (HBB: c.20A>T)/β-thalassemia (Hb S/β-thal) participating in the Recipient Epidemiology and Donor Evaluation Study (REDS-III) Brazil Sickle Cell Disease cohort. HBB gene sequencing was performed to genotype each β-thal mutation. Patients were classified as Hb S/β⁰-thal, Hb S/β⁺-thal-severe or Hb S/β⁺-thal based on prior literature and databases of hemoglobin (Hb) variants. Characteristics of patients with each β-thal mutation were described and the clinical profile of patients grouped into Hb S/β⁰-thal, Hb S/β⁺-thal and Hb S/β⁺-thal-severe were compared. Of the 2793 patients enrolled, 84 (3.0%) had Hb S/β⁰-thal and 83 (3.0%) had Hb S/β⁺-thal; 40/83 (48.2%) patients with Hb S/β⁺-thal had mutations defined as severe. We identified 19 different β-thal mutations, eight Hb S/β⁰-thal, three Hb S/β⁺-thal-severe and eight Hb S/β⁺-thal. The most frequent β⁰ and β⁺ mutations were codon 39 (HBB: c.118C>T) and IVS-I-6 (T>C) (HBB: c.92+6T>C), respectively. Individuals with Hb S/β⁰-thal had a similar clinical and laboratory phenotype when compared to those with Hb S/β⁺-thal-severe. Individuals with Hb S/β⁺-thal-severe had significantly lower total Hb and Hb A levels and higher Hb S, white blood cell (WBC) count, platelets and hemolysis markers when compared to those with Hb S/β⁺-thal. Likewise, individuals with Hb S/β⁺-thal-severe showed a significantly higher occurrence of hospitalizations, vaso-occlusive events (VOE), acute chest syndrome (ACS), splenic sequestration, blood utilization, and hydroxyurea (HU) therapy.

[Sickle cell retinopathy in children: Report of 42 cases]

We aimed to describe the epidemiological, etiological and clinical features, treatment and clinical course of sickle cell retinopathy in children and to determine the risk factors for serious involvement.

METHODS

This was a retrospective study including all children diagnosed with sickle cell retinopathy. Epidemiological, clinical and therapeutic characteristics, as well as clinical course, were analysed retrospectively by chart review. Two groups were defined: Group 1 (Goldberg stage 1 and 2); Group 2 (Goldberg stage 3, 4 and 5). In order to identify factors independently associated with severe sickle cell retinopathy, we conducted a logistic regression analysis in descending order.

RESULTS

The frequency of sickle cell retinopathy was 14.48%. Forty-two patients (84 eyes) were included; among them 23 boys and 19 girls, aged 10 to 17 with a mean age of 14±1.98 years. Twenty patients were of genotype SS, 11 patients of genotype SC, 8 Sβ and 3 SO Arab. The three patients in group 2 were all of SS genotype. The majority of patients (32) had an HbF level of less than 15%. All our patients had sickle cell retinopathy distributed as follows: 62% at stage 1; 31% at stage 2; 5% at stage 3 and 2% at stage 4. Multivariate analysis revealed a single risk factor independently linked to severe involvement - an HbF level<15%.

CONCLUSION

Retinopathy is a frequent complication of sickle cell disease which may lead to blindness. The HbF level is negatively correlated with severe involvement.

Treatment for avascular necrosis of bone in people with sickle cell disease

BACKGROUND

Avascular necrosis of bone is a frequent and severe complication of sickle cell disease and its treatment is not standardised. This is an update of a previously published Cochrane Review.

OBJECTIVES

To determine the impact of any surgical procedure compared with other surgical interventions or non-surgical procedures, on avascular necrosis of bone in people with sickle cell disease in terms of efficacy and safety.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Additional trials were sought from both ongoing trial registries and the reference lists of papers identified by the search strategy. Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 17 September 2019.

SELECTION CRITERIA

Randomized clinical trials comparing specific therapies for avascular necrosis of bone in people with sickle cell disease.

DATA COLLECTION AND ANALYSIS

Each author independently extracted data and assessed trial quality. The quality of the evidence was assessed using GRADE. Given only one trial was identified, meta-analyses were not possible.

MAIN RESULTS

One trial (46 participants) was eligible for inclusion. After randomization eight participants were withdrawn, mainly because they declined to participate in the trial. Data were analysed for 38 participants at the end of the trial. After a mean follow-up of three years, hip core decompression and physical therapy did not show clinical improvement when compared with physical therapy alone using the score from the original trial (an improvement of 18.1 points for those treated with intervention therapy versus an improvement of 15.7 points with control therapy). We are very uncertain whether there is any difference between groups regarding major complications (hip pain, risk ratio 0.95 (95% confidence interval 0.56 to 1.60; vaso-occlusive crises, risk ratio 1.14 (95% confidence interval 0.72 to 1.80; very low quality of evidence); and acute chest syndrome, risk ratio 1.06 (95% confidence interval 0.44 to 2.56; very low quality of evidence)). This trial did not report results on mortality or quality of life.

AUTHORS' CONCLUSIONS

We found no evidence that adding hip core decompression to physical therapy achieves clinical improvement in people with sickle cell disease with avascular necrosis of bone compared to physical therapy alone. However, we highlight that our conclusion is based on one trial with high attrition rates. Further randomized controlled trials are necessary to evaluate the role of hip-core depression for this clinical condition. Endpoints should focus on participants' subjective experience (e.g. quality of life and pain) as well as more objective 'time-to-event' measures (e.g. mortality, survival, hip longevity). The availability of participants to allow adequate trial power will be a key consideration for endpoint choice.

The Role of Patient-Physician Communication on the Use of Hydroxyurea in Adult Patients with Sickle Cell Disease

OBJECTIVE

This qualitative study analyzed the perspective of patients living with sickle cell disease (SCD) on their process of deciding whether to take hydroxyurea (HU), and the role of physician communication in patients' decision-making process.

METHODS

From October 2015 to July 2016, we conducted semi-structured interviews among patients with SCD (N = 20) that were audio-recorded and transcribed. Participants were ≥ 18 years old, a patient of an urban adult sickle cell center, able to provide informed consent, and English-speaking. We iteratively developed codes and used thematic analysis to organize the key themes.

RESULTS

Most participants were female (65%), middle aged (M = 44, SD = 12.2), and 55% were prescribed HU for an average of 10.4 (SD = 4.7) years. Participants described 3 key factors that influenced their decision regarding HU treatment: (1) lifestyle, (2) health status, and (3) HU characteristics. Four themes emerged about provider communication and HU treatment decisions: (1) provider's advisement, (2) shared decision-making, (3) "wrestled," and (4) not feeling heard.

CONCLUSION

Providers who engaged in shared decision-making empowered participants to decide whether to start HU treatment. Participants who felt their providers were not listening to their concerns expressed disengaging from HU treatment. During discussions about HU with patients living with SCD, providers must understand the multi-faceted aspects that impact patients' decision and empower patients to engage in such discussions. Further research is needed to understand the role of shared decision-making among patients with SCD to improve management of SCD.

Vaso-occlusive crisis as a predictor of symptomatic avascular necrosis in children with sickle cell disease

Avascular necrosis (AVN) is a chronic bone complication of sickle cell disease (SCD) resulting in significant morbidity. Understanding associated risk factors can facilitate risk-based screening, earlier identification, and prompt intervention. Between 1998 and 2014, 26 symptomatic cases with imaging evidence of AVN were compared 1:5 with age- and SCD genotype-matched controls (n = 128). Patients with 1-5 vaso-occlusive crisis (VOC) (OR 11.9, 95% CI, 1.4-99.9; P = 0.02) and more than 5 VOC (OR 53.6, 95% CI, 5.5-520.2; P = 0.0006) in a 5-year period were more likely to have AVN. Symptomatic patients with more than five VOC in 5 years may benefit from radiologic screening for AVN.

Measuring success: utility of biomarkers in sickle cell disease clinical trials and care

Progress in the care of sickle cell disease (SCD) has been hampered by the extreme complexity of the SCD phenotype despite its monogenic inheritance. While epidemiological studies have identified clinical biomarkers of disease severity, with a few exceptions, these have not been routinely incorporated in clinical care algorithms. Furthermore, existing biomarkers have been poorly apt at providing objective parameters to diagnose sickle cell crisis, the hallmark, acute complication of SCD. The repercussions of these diagnostic limitations are reflected in suboptimal care and scarcity of adequate outcome measures for clinical research. Recent progress in molecular and imaging diagnostics has heralded a new era of personalized medicine in SCD. Precision medicine strategies are particularly timely, since molecular therapeutics are finally on the horizon. This chapter will summarize the existing evidence and promising data on biomarkers for clinical care and research in SCD.

Gene therapy for sickle cell disease

BACKGROUND

Sickle cell disease encompasses a group of genetic disorders characterized by the presence of at least one hemoglobin S (Hb S) allele, and a second abnormal allele that could allow abnormal hemoglobin polymerisation leading to a symptomatic disorder.Autosomal recessive disorders (such as sickle cell disease) are good candidates for gene therapy because a normal phenotype can be restored in diseased cells with only a single normal copy of the mutant gene. This is an update of a previously published Cochrane Review.

OBJECTIVES

The objectives of this review are:- to determine whether gene therapy can improve survival and prevent symptoms and complications associated with sickle cell disease;- to examine the risks of gene therapy against the potential long-term gain for people with sickle cell disease.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, which comprises of references identified from comprehensive electronic database searches and searching relevant journals and abstract books of conference proceedings. We also searched online trial registries,Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 19 July 2018.

SELECTION CRITERIA

All randomised or quasi-randomised clinical trials (including any relevant phase 1, 2 or 3 trials) of gene therapy for all individuals with sickle cell disease, regardless of age or setting.

DATA COLLECTION AND ANALYSIS

No trials of gene therapy for sickle cell disease were found.

MAIN RESULTS

No trials of gene therapy for sickle cell disease were reported.

AUTHORS' CONCLUSIONS

No randomised or quasi-randomised clinical trials of gene therapy for sickle cell disease were reported. Thus, no objective conclusions or recommendations in practice can be made on gene therapy for sickle cell disease. This systematic review has identified the need for well-designed, randomised controlled trials to assess the benefits and risks of gene therapy for sickle cell disease.

Clinical and hematological profile in a newborn cohort with hemoglobin SC

OBJECTIVES

Hemoglobin SC is the second most common variant of sickle-cell disease worldwide, after hemoglobin SS. The objectives of the study were to describe the clinical and laboratory characteristics of hemoglobin SC disease in children from a newborn screening program and treated at a blood center.

METHODOLOGY

This study assessed a cohort of 461 infants born between 01/01/1999 and 12/31/2012 and followed-up until 12/31/2014. Clinical events were expressed as rates for 100 patient-years, with 95% confidence intervals. Kaplan-Meier survival curves were created.

RESULTS

The median age of patients was 9.2 years; 47.5% were female. Mean values of blood tests were: hemoglobin, 10.5g/dL; reticulocytes, 3.4%; white blood cells, 11.24×10⁹/L; platelets, 337.1×10⁹/L; and fetal hemoglobin, 6.3%. Clinical events: acute splenic sequestration in 14.8%, blood transfusion 23.4%, overt stroke in 0.2%. The incidence of painful vaso-occlusive episodes was 51 (48.9-53.4) per 100 patient-years and that of infections, 62.2 episodes (59.8-64.8) per 100 patient-years. Transcranial Doppler ultrasonography (n=71) was normal given the current reference values for SS patients. Hydroxyurea was given to ten children, all of whom improvement of painful crises. Retinopathy was observed in 20.3% of 59 children who underwent ophthalmoscopy. Avascular necrosis was detected in seven of 12 patients evaluated, predominantly in the left femur. Echocardiogram compatible with pulmonary hypertension was recorded in 4.6% of 130 children, with an estimated average systolic pulmonary artery pressure of 33.5mmHg. The mortality rate from all causes was 4.3%.

CONCLUSIONS

Clinical severity is variable in SC hemoglobinopathy. Several children have severe manifestations similar to those with SS disease.

Low nitric oxide level is implicated in sickle cell disease and its complications in Ghana

BACKGROUND

Nitric oxide (NO) plays a fundamental role in maintaining normal vasomotor tone. Recent clinical and experimental data suggest that NO may play a role in the pathogenesis and therapy of sickle cell disease (SCD). The aim of this study was to determine NO metabolites (NOx) in SCD patients at steady state and in vaso-occlusive crisis (VOC), as well as those with hemolytic clinical sub-phenotype that includes leg ulcers and priapism.

METHODOLOGY

This was a case-control cross-sectional study conducted on a total of 694 subjects including 148 comparison group HbAA, 208 HbSS SCD patients in steady state, 82 HbSC SCD patients in steady state, 156 HbSS SCD patients in VOC, 34 HbSC SCD patients in VOC, 34 HbSS SCD patients in post VOC, 21 HbSS SCD patients with leg ulcer and 11 HbSS SCD patients with priapism, with age ranging from 15 to 65 years. Laboratory diagnosis of SCD was done at the Sickle Cell Clinic of the Korle-Bu Teaching Hospital. Plasma nitric oxide metabolites were measured using Griess reagent system by ELISA method.

RESULTS

Mean NOx of 59.66±0.75 µMol/L in the comparison group was significantly different from those in steady state (P=0.02). During VOC, there was a significant reduction in mean NOx levels to 6.08±0.81 µMol/L (P<0.001). Mean NOx levels were however, significantly higher (50.97±1.68 µMol/L) (P<0.001) in the immediate postcrisis period. The mean NOx levels in the leg ulcer (21.70±1.18 µMol/L) (P<0.001) and priapism (28.97±1.27 µMol/L) (P<0.001) patients were significantly low as compared to the SCD patients in the steady state and comparison group.

CONCLUSION

This study presents the first report on plasma NOx levels in SCD complication in Ghanaian SCD patients and confirms reduced plasma NOx levels in SCD patients in general.

Symptomatic Avascular Necrosis: An Understudied Risk Factor for Acute Care Utilization by Patients with SCD

OBJECTIVES

Sickle cell disease (SCD) is associated with high healthcare utilization rates and poor outcomes in a subset of patients, although the underlying factors that predict this phenotype are poorly understood. Prior studies suggest that comorbid avascular necrosis (AVN) contributes to high healthcare utilization. We sought to clarify whether AVN independently predicts acute care utilization in adults with SCD and to identify characteristics of those with AVN that predict higher utilization.

METHODS

We reviewed the medical records of 87 patients with SCD with symptomatic AVN and compared acute care utilization and clinical characteristics with 87 sex- and age-matched patients with SCD without symptomatic AVN. Patients with ≥2 years of follow-up were included. Outcomes were compared using bivariate analysis and multivariate regression.

RESULTS

Our study included 1381 follow-up years, with a median of 7 years per patient. The AVN cohort had greater median rates of urgent care visits (3.2/year vs 1.3/year; P = 0.0155), admissions (1.3/year vs 0.4/year; P = 0.0002), and admission days (5.1 days/year vs 1.8 days/year; P = 0.0007). History of high utilization (odds ratio [OR] 4.28; P = 0.001), acute chest syndrome (OR 3.12; P = 0.005), pneumonia (OR 3.20; P = 0.023), hydroxyurea therapy (OR 2.23; P = 0.0136), and long-term transfusion (OR 2.33; P = 0.014) were associated with AVN. In a median regression model, AVN, acute chest syndrome, and pneumonia were independently associated with greater urgent care visits and admissions.

CONCLUSIONS

Symptomatic AVN was found to be an independent risk factor for acute care utilization in patients with SCD. Because this is a potentially modifiable factor, further studies are urgently needed to determine whether AVN prevention/early treatment interventions will alter utilization and improve outcomes for patients with SCD.

Knowledge insufficient: the management of haemoglobin SC disease

Although haemoglobin SC (HbSC) accounts for 30% of sickle cell disease (SCD) in the United States and United Kingdom, evidence-based guidelines for genotype specific management are lacking. The unique pathology of HbSC disease is complex, characterized by erythrocyte dehydration, intracellular sickling and increased blood viscosity. The evaluation and treatment of patients with HbSC is largely inferred from studies of SCD consisting mostly of haemoglobin SS (HbSS) patients. These studies are underpowered to allow definitive conclusions about HbSC. We review the pathophysiology of HbSC disease, including known and potential differences between HbSS and HbSC, and highlight knowledge gaps in HbSC disease management. Clinical and translational research is needed to develop targeted treatments and to validate management recommendations for efficacy, safety and impact on quality of life for people with HbSC.

Gene therapy for sickle cell disease

BACKGROUND

Sickle cell disease encompasses a group of genetic disorders characterized by the presence of at least one hemoglobin S (Hb S) allele, and a second abnormal allele that could allow abnormal hemoglobin polymerisation leading to a symptomatic disorder.Autosomal recessive disorders (such as sickle cell disease) are good candidates for gene therapy because a normal phenotype can be restored in diseased cells with only a single normal copy of the mutant gene. This is an update of a previously published Cochrane Review.

OBJECTIVES

The objectives of this review are:to determine whether gene therapy can improve survival and prevent symptoms and complications associated with sickle cell disease;to examine the risks of gene therapy against the potential long-term gain for people with sickle cell disease.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, which comprises of references identified from comprehensive electronic database searches and searching relevant journals and abstract books of conference proceedings.Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 15 August 2016.

SELECTION CRITERIA

All randomised or quasi-randomised clinical trials (including any relevant phase 1, 2 or 3 trials) of gene therapy for all individuals with sickle cell disease, regardless of age or setting.

DATA COLLECTION AND ANALYSIS

No trials of gene therapy for sickle cell disease were found.

MAIN RESULTS

No trials of gene therapy for sickle cell disease were reported.

AUTHORS' CONCLUSIONS

No randomised or quasi-randomised clinical trials of gene therapy for sickle cell disease were reported. Thus, no objective conclusions or recommendations in practice can be made on gene therapy for sickle cell disease. This systematic review has identified the need for well-designed, randomised controlled trials to assess the benefits and risks of gene therapy for sickle cell disease.

Treatment for avascular necrosis of bone in people with sickle cell disease

BACKGROUND

Avascular necrosis of bone is a frequent and severe complication of sickle cell disease and its treatment is not standardised. This is an update of a previously published Cochrane Review.

OBJECTIVES

To determine the impact of any surgical procedure compared with other surgical interventions or non-surgical procedures, on avascular necrosis of bone in people with sickle cell disease in terms of efficacy and safety.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Additional trials were sought from the reference lists of papers identified by the search strategy.Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 27 May 2016.

SELECTION CRITERIA

Randomized clinical trials comparing specific therapies for avascular necrosis of bone in people with sickle cell disease.

DATA COLLECTION AND ANALYSIS

Each author independently extracted data and assessed trial quality. Since only one trial was identified, meta-analysis was not possible.

MAIN RESULTS

One trial (46 participants) was eligible for inclusion. After randomization eight participants were withdrawn, mainly because they declined to participate in the trial. Data were analysed for 38 participants at the end of the trial. After a mean follow up of three years, hip core decompression and physical therapy did not show clinical improvement when compared with physical therapy alone using the score from the original trial (an improvement of 18.1 points for those treated with intervention therapy versus an improvement of 15.7 points with control therapy). There was no significant statistical difference between groups regarding major complications (hip pain, risk ratio 0.95 (95% confidence interval 0.56 to 1.60; vaso-occlusive crises, risk ratio 1.14 (95% confidence interval 0.72 to 1.80; very low quality of evidence); and acute chest syndrome, risk ratio 1.06 (95% confidence interval 0.44 to 2.56; very low quality of evidence)). This trial did not report results on mortality or quality of life.

AUTHORS' CONCLUSIONS

We found no evidence that adding hip core decompression to physical therapy achieves clinical improvement in people with sickle cell disease with avascular necrosis of bone compared to physical therapy alone. However, we highlight that our conclusion is based on one trial with high attrition rates. Further randomized controlled trials are necessary to evaluate the role of hip-core depression for this clinical condition. Endpoints should focus on participants' subjective experience (e.g. quality of life and pain) as well as more objective 'time-to-event' measures (e.g. mortality, survival, hip longevity). The availability of participants to allow adequate trial power will be a key consideration for endpoint choice.

Chronic Opioid Therapy and Central Sensitization in Sickle Cell Disease

Chronic opioid therapy (COT) for chronic non-cancer pain is frequently debated, and its effectiveness is unproven in sickle cell disease (SCD). The authors conducted a descriptive study among 83 adult SCD patients and compared the severity of disease and pain symptoms among those who were prescribed COT (n=29) with those who were not using COT. All patients completed baseline laboratory pain assessment and questionnaires between January 2010 and June 2014. Thereafter, participants recorded daily pain, crises, function, and healthcare utilization for 90 days using electronic diaries. Analyses were conducted shortly after the final diary data collection period. Patients on COT did not differ on age, sex, or measures of disease severity. However, patients on COT exhibited greater levels of clinical pain (particularly non-crisis); central sensitization; and depression and increased diary measures of pain severity, function, and healthcare utilization on crisis and non-crisis diary days, as well as a greater proportion of days in crisis. Including depressive symptoms in multivariate models did not change the associations between COT and pain, interference, central sensitization, or utilization. Additionally, participants not on COT displayed the expected positive relationship between central sensitization and clinical pain, whereas those on COT demonstrated no such relationship, despite having both higher central sensitization and higher clinical pain. Overall, the results point out a high symptom burden in SCD patients on COT, including those on high-dose COT, and suggest that nociceptive processing in SCD patients on COT differs from those who are not.

Original Research: Use of hydroxyurea and phlebotomy in pediatric patients with hemoglobin SC disease

Hydroxyurea is an excellent therapeutic agent for the pharmacological induction of HbF in patients with sickle cell disease (SCD). However, all completed clinical trials of hydroxyurea have excluded patients with hemoglobin SC (HbSC) disease. HbSC differs significantly in pathophysiology from HbSS, as HbC does not sickle, but instead causes cellular dehydration which potentiates sickling of HbS. Many severely affected HbSC patients have been placed on hydroxyurea on a case by case basis, but there are no large scale prospective data on safety or efficacy of hydroxyurea in this subset of patients with SCD. Here, we report a case series of 14 pediatric patients with HbSC treated to maximum tolerated dose (MTD) with hydroxyurea. Those who failed to show clinical improvement after at least six months at MTD were offered phlebotomy in addition to hydroxyurea. Five out of 11 patients with HbSC who achieved MTD failed to demonstrate clinical improvement on hydroxyurea. Of the four placed on dual hydroxyurea and phlebotomy therapy, all showed at least partial clinical improvement. Percent dense red blood cells (%DRBC) were measured via an ADVIA hematology analyzer. A marked rise in percent dense cells preceded clinical complications in three patients. Dual therapy with hydroxyurea and phlebotomy may be an effective approach to patients with HbSC that do not experience improvement with hydroxyurea alone. Monitoring of %DRBC may predict adverse events and aid in assessing hydroxyurea compliance. Large scale clinical trials are needed to evaluate the safety and efficacy of hydroxyurea and hydroxyurea with phlebotomy in patients with HbSC disease.

Effects of hydroxyurea treatment for patients with hemoglobin SC disease

Although hemoglobin SC (HbSC) disease is usually considered less severe than sickle cell anemia (SCA), which includes HbSS and HbS/β(0) -thalassemia genotypes, many patients with HbSC experience severe disease complications, including vaso-occlusive pain, acute chest syndrome, avascular necrosis, retinopathy, and poor quality of life. Fully 20 years after the clinical and laboratory efficacy of hydroxyurea was proven in adult SCA patients, the safety and utility of hydroxyurea treatment for HbSC patients remain unclear. Recent NHLBI evidence-based guidelines highlight this as a critical knowledge gap, noting HbSC accounts for ∼30% of sickle cell patients within the United States. To date, only 5 publications have reported short-term, incomplete, or conflicting laboratory and clinical outcomes of hydroxyurea treatment in a total of 71 adults and children with HbSC. We now report on a cohort of 133 adult and pediatric HbSC patients who received hydroxyurea, typically for recurrent vaso-occlusive pain. Hydroxyurea treatment was associated with a stable hemoglobin concentration; increased fetal hemoglobin (HbF) and mean corpuscular volume (MCV); and reduced white blood cell count (WBC), absolute neutrophil count (ANC), and absolute reticulocyte count (ARC). Reversible cytopenias occurred in 22% of patients, primarily neutropenia and thrombocytopenia. Painful events were reduced with hydroxyurea, more in patients >15 years old. These multicenter data support the safety and potentially salutary effects of hydroxyurea treatment for HbSC disease; however, a multicenter, placebo-controlled, Phase 3 clinical trial is needed to determine if hydroxyurea therapy has efficacy for patients with HbSC disease.

Kidney Disease among Patients with Sickle Cell Disease, Hemoglobin SS and SC

BACKGROUND AND OBJECTIVES

Sickle cell disease (SCD) is an inherited anemia that afflicts millions worldwide. Kidney disease is a major contributor to its morbidity and mortality. We examined contemporary and historical SCD populations to understand how renal disease behaved in hemoglobin SS (HbSS) compared with HbSC.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Kidney function was examined in the multicentered Treatment of Pulmonary Hypertension and Sickle Cell Disease with Sildenafil Therapy (Walk-PHaSST) Trial (HbSS=463; HbSC=127; years 2007-2009) and historical comparator populations from the Cooperative Study of Sickle Cell Disease (CSSCD; HbSS=708) and the Multicenter Study of Hydroxyurea in Sickle Cell Disease (MSH; HbSS=299).

RESULTS

In adults with SCD, eGFR was lower among older individuals: -1.78 ml/min per 1.73 m(2) per year of age (95% confidence interval [95% CI], -2.06 to -1.50; Walk-PHaSST Trial), -1.75 ml/min per 1.73 m(2) per year of age (95% CI, -2.05 to -1.44; MSH), and -1.69 ml/min per 1.73 m(2) per year of age (95% CI, -2.00 to -1.38; CSSCD) in HbSS compared with -1.09 ml/min per 1.73 m(2) per year of age (95% CI, -1.39 to -0.75) in HbSC (Walk-PHaSST Trial). Macroalbuminuria was seen in 20% of participants with SCD (HbSS or HbSC; P=0.45; Walk-PHaSST Trial), but microalbuminuria was more prevalent in HbSS (44% versus 23% in HbSC; P<0.002). In the Walk-PHaSST Trial, albuminuria was associated with hemolysis (higher lactate dehydrogenase, P<0.001; higher absolute reticulocyte count, P<0.02; and lower Hb, P=0.07) and elevated systolic BP (P<0.001) in HbSS. One half of all participants with HbSS (20 of 39) versus one fifth without (41 of 228) elevated tricuspid regurgitant jet velocity (≥3 m/s; adverse prognostic indicator in SCD) had macroalbuminuria (P<0.001). In the CSSCD, overt proteinuria, detected (less sensitively) by urine dipstick, associated with higher 3-year mortality (odds ratio, 2.48; 95% CI, 1.07 to 5.77). Serum bicarbonate was lower in HbSS (23.8 versus 24.8 mEq/dl in HbSC; P<0.05) and associated with reticulocytopenic anemia and decreased renal function.

CONCLUSIONS

In SCD, albuminuria or proteinuria was highly prevalent, in HbSS more than in HbSC. Proteinuria associated with mortality in HbSS. Older individuals had a lower than expected eGFR, and this was more prominent in HbSS. Current management does not routinely address renal complications in SCD, which could plausibly reduce morbidity and mortality.

Cohort study of adult patients with haemoglobin SC disease: clinical characteristics and predictors of mortality

Haemoglobin (Hb) SC disease is the second most common subtype of sickle cell disease and is potentially fatal. This study aimed to determine the clinical characteristics, outcome and predictors of mortality in HbSC disease patients, and to compare these findings with patients followed-up in different centres. Clinical, laboratory and outcome data were collected from a cohort of adult patients with HbSC disease followed between 1991 and 2103. Cox regression multivariate analysis was used to determine predictors of mortality. One hundred and fifty-five patients were followed-up over 20 years: 9% died and 70·8% had at least one complication. The most common complications were: painful crises (38·3%), retinopathy (33·8%), cholelithiasis (30·3%), osteonecrosis (24·8%) and sensorineural hearing disorders (9·7%). Frequency of chronic complications was similar in most studies. In multivariate analysis, hearing disorders remained an independent predictor of mortality (Odds Ratio 9·26, 95% confidence interval 1·1-74·8; P = 0·03). It was concluded that patients with HbSC disease receive a late diagnosis and there is remarkable similarity between the studies conducted in different centres around the world. Sensorineural hearing disorders were an independent predictor of mortality, suggesting that it may be useful to implement routine diagnostic screening.

Severity of Brazilian sickle cell disease patients: severity scores and feasibility of the Bayesian network model use

The integration of the several clinical and laboratory dimensions and the influence of each parameter on the sickle cell disease (SCD)-related mortality is useful for predicting the phenotype of an individual. This study evaluated the feasibility of the SCD severity calculator use to measure disease severity in Brazilian patients. The study group was composed of 500 SCD patients (440 HbSS and 60 HbSC) diagnosed by molecular biology. We observed a decrease in severity scores in 72 SCD patients assessed before and after the hydroxyurea (HU) use. Furthermore, the HU influenced the increase of mean corpuscular volume (MCV) and HbF concentration, and the decrease of leukocytes and total bilirubin. We found 180 (36.0%) patients with intermediate phenotype, 170 (34.0%) mild phenotype and 150 (30.0%) with severe phenotype. Patients with ages >40 years had higher mean score (0.778±0.177) than patients between 18 and 40 years (0.562±0.152) and patients between 5 and 17 years (0.322±0.145). We observe that there is a tendency of individuals with leg ulcers, avascular necrosis and cardiac complications with increasing age. Correlation analysis showed relations between severity scores with leukocytes, reticulocytes, bilirubin, lactate dehydrogenase, HbS, hemoglobin and hematocrit (p<0.05). Several comparisons involving age groups, SCD genotype and phenotypic classification had satisfactory results and this classification will be used for future studies involving genetic polymorphisms, response to treatment with HU and oxidative stress markers in SCD.

Gene therapy for sickle cell disease

BACKGROUND

Sickle cell disease encompasses a group of genetic disorders characterized by the presence of at least one hemoglobin S (Hb S) allele, and a second abnormal allele that could allow abnormal hemoglobin polymerisation leading to a symptomatic disorder.Autosomal recessive disorders (such as sickle cell disease) are good candidates for gene therapy because a normal phenotype can be restored in diseased cells with only a single normal copy of the mutant gene.

OBJECTIVES

The objectives of this review are:- to determine whether gene therapy can improve survival and prevent symptoms and complications associated with sickle cell disease;- to examine the risks of gene therapy against the potential long-term gain for people with sickle cell disease.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, which comprises of references identified from comprehensive electronic database searches and searching relevant journals and abstract books of conference proceedings.Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 21 July 2014.

SELECTION CRITERIA

All randomised or quasi-randomised clinical trials (including any relevant phase 1, 2 or 3 trials) of gene therapy for all individuals with sickle cell disease, regardless of age or setting.

DATA COLLECTION AND ANALYSIS

No trials of gene therapy for sickle cell disease were found.

MAIN RESULTS

No trials of gene therapy for sickle cell disease were reported.

AUTHORS' CONCLUSIONS

No randomised or quasi-randomised clinical trials of gene therapy for sickle cell disease were reported. Thus, no objective conclusions or recommendations in practice can be made on gene therapy for sickle cell disease. This systematic review has identified the need for well-designed, randomised controlled trials to assess the benefits and risks of gene therapy for sickle cell disease.

The ethics of a proposed study of hematopoietic stem cell transplant for children with “less severe” sickle cell disease

Hematopoietic stem cell transplant (HSCT) is the only cure for sickle cell disease (SCD). HSCT using an HLA-identical sibling donor is currently an acceptable treatment option for children with severe SCD, with expected HSCT survival >95% and event-free survival >85%. HSCT for children with less severe SCD (children who have not yet suffered overt disease complications or only had mild problems) is controversial. It is important to consider the ethical issues of a proposed study comparing HLA-identical sibling HSCT to best supportive care for children with less severe SCD. In evaluating the principles of nonmaleficence, respect for individual autonomy, and justice, we conclude that a study of HLA-identical sibling HSCT for all children with SCD, particularly hemoglobin SS and Sβ0-thalassemia disease, is ethically sound. Future work should explore the implementation of a large trial to help determine whether HSCT is a beneficial treatment of children with less severe SCD.

Treatment for avascular necrosis of bone in people with sickle cell disease

BACKGROUND

Avascular necrosis of bone is a frequent and severe complication of sickle cell disease and its treatment is not standardised.

OBJECTIVES

To determine the impact of any surgical procedure compared with other surgical interventions or non-surgical procedures, on avascular necrosis of bone in people with sickle cell disease in terms of efficacy and safety.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Additional trials were sought from the reference lists of papers identified by the search strategy.Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 17 March 2014.

SELECTION CRITERIA

Randomised clinical trials comparing specific therapies for avascular necrosis of bone in people with sickle cell disease.

DATA COLLECTION AND ANALYSIS

Each author independently extracted data and assessed trial quality. Since only one trial was identified, meta-analysis was not possible.

MAIN RESULTS

One trial (46 participants) was eligible for inclusion. After randomisation eight participants were withdrawn, mainly because they declined to participate in the trial. Data were analysed for 38 participants at the end of the trial. After a mean follow up of three years, hip core decompression and physical therapy did not show clinical improvement when compared with physical therapy alone using the score from the original trial (an improvement of 18.1 points for those treated with intervention therapy versus an improvement of 15.7 points with control therapy). There was no significant statistical difference between groups regarding major complications (hip pain, relative risk (RR) 0.95 (95% confidence interval (CI) 0.56 to 1.60; vaso-occlusive crises, RR 1.14 (95% CI 0.72 to 1.80; very low quality of evidence); and acute chest syndrome, RR 1.06 (95% CI 0.44 to 2.56; very low quality of evidence)). This trial did not report results on mortality or quality of life.

AUTHORS' CONCLUSIONS

We found no evidence that adding hip core decompression to physical therapy achieves clinical improvement in people with sickle cell disease with avascular necrosis of bone compared to physical therapy alone. However, we highlight that our conclusion is based on one trial with high attrition rates. Further randomised controlled trials are necessary to evaluate the role of hip-core depression for this clinical condition. Endpoints should focus on participants' subjective experience (e.g. quality of life and pain) as well as more objective 'time-to-event' measures (e.g. mortality, survival, hip longevity). The availability of participants to allow adequate trial power will be a key consideration for endpoint choice.

Nucleosomes and neutrophil activation in sickle cell disease painful crisis

Activated polymorphonuclear neutrophils play an important role in the pathogenesis of vaso-occlusive painful sickle cell crisis. Upon activation, polymorphonuclear neutrophils can form neutrophil extracellular traps. Neutrophil extracellular traps consist of a meshwork of extracellular DNA, nucleosomes, histones and neutrophil proteases. Neutrophil extracellular traps have been demonstrated to be toxic to endothelial and parenchymal cells. This prospective cohort study was conducted to determine neutrophil extracellular trap formation in sickle cell patients during steady state and painful crisis. As a measure of neutrophil extracellular traps, plasma nucleosomes levels were determined and polymorphonuclear neutrophil activation was assessed measuring plasma levels of elastase-α1-antitrypsin complexes in 74 patients in steady state, 70 patients during painful crisis, and 24 race-matched controls using Enzyme Linked Immunosorbent Assay. Nucleosome levels in steady state sickle cell patients were significantly higher than levels in controls. During painful crisis levels of both nucleosomes and elastase-α1-antitrypsin complexes increased significantly. Levels of nucleosomes correlated significantly to elastase-α1-antitrypsin complex levels during painful crisis, (Sr = 0.654, P<0.001). This was seen in both HbSS/HbSβ(0)-thalassemia (Sr=0.55, P<0.001) and HbSC/HbSβ(+-)thalassemia patients (Sr=0.90, P<0.001) during painful crisis. Levels of nucleosomes showed a correlation with length of hospital stay and were highest in patients with acute chest syndrome. These data support the concept that neutrophil extracellular trap formation and neutrophil activation may play a role in the pathogenesis of painful sickle cell crisis and acute chest syndrome.

Online biomedical resources for malaria-related red cell disorders

Warnings about the expected increase of the global public health burden of malaria-related red cell disorders are accruing. Past and present epidemiological data are necessary to track spatial and temporal changes in the frequencies of these genetic disorders. A number of open access biomedical databases including data on malaria-related red cell disorders have been launched over the last two decades. Here, we review the content of these databases, most of which focus on genetic diversity, and we describe a new epidemiological resource developed by the Malaria Atlas Project. To tackle upcoming public health challenges, the integration of epidemiological and genetic data is important. As many countries are considering implementing national screening programs, strategies to make such data more accessible are also needed.

Age-related treatment patterns in sickle cell disease patients and the associated sickle cell complications and healthcare costs

BACKGROUND

This study explored the blood transfusion patterns, SCD complications, utilization of iron chelation therapies (ICT), healthcare resource use, and costs in pediatric, transitioning (18 years old) and adult patients with SCD.

PROCEDURE

Data from Florida (1998-2009), New Jersey (1996-2009), Missouri (1997-2010), Kansas (2001-2009), and Iowa (1998-2010) state Medicaid were used. Patients with ≥2 SCD diagnoses and ≥1 transfusion event were included. Rates of transfusion events, SCD complications, and proportion of eligible patients receiving ICT were calculated. ICT eligibility was defined as receiving ≥10 transfusions over lifetime. SCD complications included pain, pulmonary event, infection event, renal, cardiovascular, stroke, leg ulcers, and avascular necrosis. Regressions were used to assess risk factors for transfusion and identify the main drivers of costs.

RESULTS

The sample included 3,208 patients. The transfusion rate increased from 1-year-old to a peak at 16 years old, then dropped until age 26 and remained stable thereafter. In contrast the frequency of diagnoses for SCD complications increased markedly after age 16. Post-transition patients (≥18 years old) were significantly associated with fewer transfusions (odds ratio: 0.80, P = 0.002). Among eligible patients for ICT, there was no statistically significant difference in total cost between the ICT and no ICT groups (adjusted cost difference, $136, P = 0.114).

CONCLUSIONS

Patients transitioning to adult care received less transfusions and hydroxyurea, less ICT when eligible for chelation therapy, had higher healthcare costs and suffered from more frequent SCD related complications than pediatric patients. These findings highlight the changes in treatment patterns corresponding to transition to adult care.

Gene therapy for sickle cell disease

BACKGROUND

Sickle cell disease encompasses a group of genetic disorders characterized by the presence of at least one hemoglobin S (Hb S) allele, and a second abnormal allele that could allow abnormal hemoglobin polymerisation leading to a symptomatic disorder.Autosomal recessive disorders (such as sickle cell disease) are good candidates for gene therapy because a normal phenotype can be restored in diseased cells with only a single normal copy of the mutant gene.

OBJECTIVES

The objectives of this review are:- to determine whether gene therapy can improve survival and prevent symptoms and complications associated with sickle cell disease;- to examine the risks of gene therapy against the potential long-term gain for people with sickle cell disease.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, which comprises of references identified from comprehensive electronic database searches and searching relevant journals and abstract books of conference proceedings.Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 21 June 2012.

SELECTION CRITERIA

All randomised or quasi-randomised clinical trials (including any relevant phase 1, 2 or 3 trials) of gene therapy for all individuals with sickle cell disease, regardless of age or setting.

DATA COLLECTION AND ANALYSIS

No trials of gene therapy for sickle cell disease were found.

MAIN RESULTS

No trials of gene therapy for sickle cell disease were reported.

AUTHORS' CONCLUSIONS

No randomised or quasi-randomised clinical trials of gene therapy for sickle cell disease were reported. Thus, no objective conclusions or recommendations in practice can be made on gene therapy for sickle cell disease. This systematic review has identified the need for well-designed, randomised controlled trials to assess the benefits and risks of gene therapy for sickle cell disease.

Shorter hospitalization trends among children with sickle cell disease

BACKGROUND

Vaso-occlusive crises (VOC) contribute to frequent hospitalizations among children with sickle cell disease (SCD). The objective of this study was to determine whether length of stay (LOS) has decreased for VOC hospitalizations between 1997 and 2009.

PROCEDURE

We analyzed pediatric discharges (aged 0-18) with a primary or secondary diagnosis of SCD with crisis from the Kid's Inpatient Database (years 1997, 2003, and 2009), a nationally representative sample of pediatric hospital discharges. We conducted bivariate and multivariate, sample-weighted linear regression analyses to determine associations between independent variables (patient demographics, hospital characteristics, co-diagnoses, and procedures) and LOS.

RESULTS

Both the number (22,661-21,741) and proportion of VOC hospitalizations (0.34-0.29%) among all pediatric hospitalizations marginally decreased between 1997 and 2009 (P < 0.01). Mean LOS decreased from 4.59 to 4.21 days (P < 0.01). For all study years, older age was the only socio-demographic variable associated with longer LOS, controlling for other factors. Between 1997 and 2009, LOS decreased for all age categories, with the largest statistically significant reduction occurring among adolescents (5.69-4.76 days).

CONCLUSIONS

Nationally representative hospital data indicate modest but meaningful reductions in LOS for children with VOC over a 12-year period. Adolescents who typically have the greatest disease severity showed the largest reduction in LOS. However, adolescents continue to account for a large proportion of inpatient stays for VOC. These findings illustrate that the adolescent period is a critical time in the lifespan for targeted intervention.

Pregnancy outcomes among patients with sickle cell disease at Korle-Bu Teaching Hospital, Accra, Ghana: retrospective cohort study

Pregnancy in sickle cell disease (SCD) patients is associated with increased risk of maternal and fetal mortality. This study determines pregnancy outcomes among women with SCD delivering at Korle-Bu Teaching Hospital, Accra, Ghana. Nine hundred sixty (960) medical records of pregnant women (131 HbSS, 112 HbSC, and 717 comparison group) from 2007 to 2008 were reviewed. The HbSS women were at increased risk of eclampsia (adjusted odds ratio [AOR] = 10.56, 95% confidence interval [CI] = 3.60-30.96, P < 0.001), intrauterine growth restriction (AOR = 4.00, 95% CI = 1.38-11.64, P = 0.011), and placenta previa (AOR = 22.03, 95% CI = 9.87-49.14, P < 0.001) compared with the comparison group. The HbSC women had increased risk for intrauterine fetal death (AOR = 3.38, 95% CI = 1.15-9.96, P = 0.027) and decreased risk of delivering low birth weight babies (AOR = 0.21, 95% CI = 0.06-0.73, P = 0.014). Women with SCD in Ghana are at a greater risk of morbidity and mortality in pregnancy compared with women without hemoglobinopathies. Improved maternal and fetal outcomes in Ghanaian women with SCD can be achieved through effective intervention by health care providers with thorough knowledge about predisposing factors toward adverse outcomes.

Beyond the definitions of the phenotypic complications of sickle cell disease: an update on management

The sickle hemoglobin is an abnormal hemoglobin due to point mutation (GAG → GTG) in exon 1 of the β globin gene resulting in the substitution of glutamic acid by valine at position 6 of the β globin polypeptide chain. Although the molecular lesion is a single-point mutation, the sickle gene is pleiotropic in nature causing multiple phenotypic expressions that constitute the various complications of sickle cell disease in general and sickle cell anemia in particular. The disease itself is chronic in nature but many of its complications are acute such as the recurrent acute painful crises (its hallmark), acute chest syndrome, and priapism. These complications vary considerably among patients, in the same patient with time, among countries and with age and sex. To date, there is no well-established consensus among providers on the management of the complications of sickle cell disease due in part to lack of evidence and in part to differences in the experience of providers. It is the aim of this paper to review available current approaches to manage the major complications of sickle cell disease. We hope that this will establish another preliminary forum among providers that may eventually lead the way to better outcomes.

Treatment for avascular necrosis of bone in people with sickle cell disease

BACKGROUND

Avascular necrosis of bone is a frequent and severe complication of sickle cell disease and its treatment is not standardised.

OBJECTIVES

To determine the impact of any surgical procedure compared with other surgical interventions or non-surgical procedures, on avascular necrosis of bone in people with sickle cell disease in terms of efficacy and safety.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Additional trials were sought from the reference lists of papers identified by the search strategy.Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 21 February 2012.

SELECTION CRITERIA

Randomised clinical trials comparing specific therapies for avascular necrosis of bone in people with sickle cell disease.

DATA COLLECTION AND ANALYSIS

Each author independently extracted data and assessed trial quality. Since only one trial was identified, meta-analysis was not possible.

MAIN RESULTS

One trial (46 participants) was eligible for inclusion. After randomisation eight participants were withdrawn, mainly because they declined to participate in the trial. Data were analysed for 38 participants at the end of the trial. After a mean follow up of three years, hip core decompression and physical therapy did not show clinical improvement when compared with physical therapy alone using the score from the original trial (an improvement of 18.1 points for those treated with intervention therapy versus an improvement of 15.7 points with control therapy). There was no significant statistical difference between groups regarding major complications (hip pain, relative risk (RR) 0.95 (95% confidence interval (CI) 0.56 to 1.60; vaso-occlusive crises, RR 1.14 (95% CI 0.72 to 1.80); and acute chest syndrome, RR 1.06 (95% CI 0.44 to 2.56)). This trial did not report results on mortality or quality of life.

AUTHORS' CONCLUSIONS

We found no evidence that adding hip core decompression to physical therapy achieves clinical improvement in people with sickle cell disease with avascular necrosis of bone compared to physical therapy alone. However, we highlight that our conclusion is based on one trial with high attrition rates. Further randomised controlled trials are necessary to evaluate the role of hip-core depression for this clinical condition. Endpoints should focus on participants' subjective experience (e.g. quality of life and pain) as well as more objective 'time-to-event' measures (e.g. mortality, survival, hip longevity). The availability of participants to allow adequate trial power will be a key consideration for endpoint choice.

N-acetylcysteine reduces oxidative stress in sickle cell patients

Oxidative stress is of importance in the pathophysiology of sickle cell disease (SCD). In this open label randomized pilot study the effects of oral N-acetylcysteine (NAC) on phosphatidylserine (PS) expression as marker of cellular oxidative damage (primary end point), and markers of hemolysis, coagulation and endothelial activation and NAC tolerability (secondary end points) were studied. Eleven consecutive patients (ten homozygous [HbSS] sickle cell patients, one HbSβ(0)-thalassemia patient) were randomly assigned to treatment with either 1,200 or 2,400 mg NAC daily during 6 weeks. The data indicate an increment in whole blood glutathione levels and a decrease in erythrocyte outer membrane phosphatidylserine exposure, plasma levels of advanced glycation end-products (AGEs) and cell-free hemoglobin after 6 weeks of NAC treatment in both dose groups. One patient did not tolerate the 2,400 mg dose and continued with the 1,200 mg dose. During the study period, none of the patients experienced painful crises or other significant SCD or NAC related complications. These data indicate that N-acetylcysteine treatment of sickle cell patients may reduce SCD related oxidative stress.

Hemoglobin sickle cell disease complications: a clinical study of 179 cases

BACKGROUND

Hemoglobin sickle cell disease is one of the most frequent hemoglobinopathies. Surprisingly, few studies have been dedicated to this disease, currently considered to be a mild variant of homozygous sickle cell disease. The aim of this study was to update our knowledge about hemoglobin sickle cell disease.

DESIGN AND METHODS

The study involved a single center series of 179 patients. Clinical and biological data were collected with special attention to the assessment of pulmonary arterial hypertension and nephropathy.

RESULTS

Hemoglobin sickle cell diagnosis was delayed and performed in adulthood in 29% of cases. Prevalence of hospitalized painful vasoocclusive crisis, acute chest syndrome and priapism was 36%, 20% and 20%, respectively. The most common chronic organ complications were retinopathy and sensorineural otological disorders in 70% and 29% of cases. Indeed, prevalence of complications reported in homozygous sickle cell disease, such as nephropathy, suspicion of pulmonary hypertension, strokes and leg ulcers was rather low (13%, 4% and 1%, respectively). Phlebotomy performed in 36% of this population (baseline hemoglobin 11.5 g/dL) prevented recurrence of acute events in 71% of cases.

CONCLUSIONS

Our data suggest that hemoglobin sickle cell disease should not be considered as a mild form of sickle cell anemia but as a separate disease with a special emphasis on viscosity-associated otological and ophthalmological disorders, and with a low prevalence of vasculopathy (strokes, pulmonary hypertension, ulcers and nephropathy). Phlebotomy was useful in reducing acute events and a wider use of this procedure should be further investigated.

Acute chest syndrome is associated with history of asthma in hemoglobin SC disease

BACKGROUND

Acute chest syndrome (ACS) is a frequent cause of morbidity and leading cause of death among individuals with sickle cell disease. Yet, ACS in hemoglobin SC disease is not well characterized. The objective of this study was to compare the presentation and clinical course of ACS in individuals with hemoglobin SC disease to that observed in individuals with hemoglobin SS disease.

PROCEDURE

We retrospectively reviewed 71 inpatient episodes of ACS in patients with hemoglobin SC disease over a 20-year period. Continuous and categorical data from index cases were compared with that from 71 control cases of ACS in patients with hemoglobin SS disease.

RESULTS

Median length of hospitalization was shorter for hemoglobin SC episodes when compared to hemoglobin SS episodes (3.0 vs. 5.0 days, P < 0.001). In comparison to hemoglobin SS patients, a greater proportion of hemoglobin SC patients had a previous history of asthma or wheezing (50.7 vs. 33.8%, OR = 2.01 [1.02-3.96], P = 0.041) and a respiratory complaint of wheeze (11.3 vs. 2.8%, OR = 4.38 [0.90-21.4], P = 0.049). In our multivariate regression model, time to ACS diagnosis and total number of days of oxygen supplementation were independent predictors of length of hospitalization in both hemoglobin SC and SS episodes of ACS.

CONCLUSIONS

ACS appears to be less severe in children with hemoglobin SC disease compared to that in children with SS disease. Asthma and wheezing may represent more significant risk factors for the development of ACS in children with hemoglobin SC disease.