Advances in clinical research in sickle cell disease

Interventions for treating leg ulcers in people with sickle cell disease

BACKGROUND

The frequency of skin ulceration makes an important contributor to the morbidity burden in people with sickle cell disease. Many treatment options are available to the healthcare professional, although it is uncertain which treatments have been assessed for effectiveness in people with sickle cell disease. This is an update of a previously published Cochrane Review.

OBJECTIVES

To assess the clinical effectiveness and harms of interventions for treating leg ulcers in people with sickle cell disease.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register. We searched LILACS (1982 to January 2020), ISI Web of Knowledge (1985 to January 2020), and the Clinical Trials Search Portal of the World Health Organization (January 2020). We checked the reference lists of all the trials identified. We also contacted those groups or individuals who may have completed relevant randomised trials in this area. Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register: 13 January 2020; date of the last search of the Cochrane Wounds Group Trials Register: 17 February 2017.

SELECTION CRITERIA

Randomised controlled trials of interventions for treating leg ulcers in people with sickle cell disease compared to placebo or an alternative treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion. All three authors independently assessed the risk of bias of the included studies and extracted data. We used GRADE to assess the quality of the evidence.

MAIN RESULTS

Six studies met the inclusion criteria (198 participants with 250 ulcers). Each trial investigated a different intervention and within this review we have grouped these as systemic pharmaceutical interventions (L-cartinine, arginine butyrate, isoxsuprine) and topical pharmaceutical interventions (Solcoseryl® cream, arginine-glycine-aspartic acid (RGD) peptide dressing and topical antibiotics). No trials on non-pharmaceutical interventions were included in the review. All trials had an overall unclear or high risk of bias, and drug companies sponsored four of them. We were unable to pool findings due to the heterogeneity in outcome definitions, and inconsistency between the units of randomisation and analysis. Three interventions reported on the change in ulcer size (arginine butyrate, RGD peptide, L-cartinine). Of these, only arginine butyrate showed a reduction of ulcer size compared with a control group, mean reduction -5.10 cm² (95% CI -9.65 to -0.55), but we are uncertain whether this reduces ulcer size compared to standard care alone as the certainty of the evidence has been assessed as very low. Three trials reported on complete leg ulcer closure (isoxsuprine, arginine butyrate, RGD peptide matrix; very low quality of evidence). None reported a clinical benefit. No trial reported on: the time to complete ulcer healing; ulcer-free survival following treatment for sickle cell leg ulcers; quality of life measures; incidence of amputation or harms.

AUTHORS' CONCLUSIONS

Given the very low quality of the evidence identified in this updated Cochrane Review we are uncertain whether any of the assessed pharmaceutical interventions reduce ulcer size or result in leg ulcer closure in treated participants compared to controls. However, this intervention was assessed as having a high risk of bias due to inadequacies in the single trial report. Other included studies were also assessed as having an unclear or high risk of bias. The harm profile of the all interventions remains inconclusive.

Effect of N(Epsilon)-(carboxymethyl)lysine on Laboratory Parameters and Its Association with β S Haplotype in Children with Sickle Cell Anemia

The present study aimed to investigate the association of N^ε-carboxymethyllysine (CML) with laboratory parameters and β^S haplotypes in pediatric sickle cell anemia (SCA) patients with or without hydroxyurea (HU) therapy. We included 55 children with SCA (SCA_total), where 27 were on HU treatment (SCA-HU⁺) and 28 without HU treatment (SCA-HU⁻). Laboratory characteristics were determined using electronic methods while CML was measured using competitive ELISA. β^S haplotypes were determined by RFLP-PCR. Significant increases in MCV and MCH and significant decreases in leukocytes, eosinophils, basophils, atypical lymphocytes, lymphocytes, and monocytes were found in SCA-HU⁺ compared to SCA-HU⁻. SCA-HU⁺ presented significant reduction in aspartate transaminase and lactate dehydrogenase and increase in creatinine levels compared to SCA-HU⁻. CML levels were significantly higher in both SCA-HU⁺ and SCA-HU⁻ compared to the healthy control. In addition, a negative correlation was found between CML and alanine transaminase in SCA-HU⁺ and SCA_total (p < 0.01). A significant association was found between CML levels and β^S haplotypes. The results suggest that CML has a role to play in SCA complications, independent of HU therapy.

Antibiotics for treating osteomyelitis in people with sickle cell disease

BACKGROUND

Osteomyelitis (both acute and chronic) is one of the most common infectious complications in people with sickle cell disease. There is no standardized approach to antibiotic therapy and treatment is likely to vary from country to country. Thus, there is a need to identify the efficacy and safety of different antibiotic treatment approaches for people with sickle cell disease suffering from osteomyelitis. This is an update of a previously published Cochrane Review.

OBJECTIVES

To determine whether an empirical antibiotic treatment approach (monotherapy or combination therapy) is effective and safe as compared to pathogen-directed antibiotic treatment and whether this effectiveness and safety is dependent on different treatment regimens, age or setting.

SEARCH METHODS

We searched The Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to 20 October 2016), African Index Medicus (20 October 2016), ISI Web of Knowledge (20 October 2016) and clinical trials registries (19 September 2019).Date of most recent search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register: 18 September 2019.

SELECTION CRITERIA

We searched for published or unpublished randomised and quasi-randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data and assess trial quality by standard Cochrane methodologies, but no eligible randomised controlled trials were identified.

MAIN RESULTS

This update was unable to find any randomised or quasi-randomised controlled trials on antibiotic treatment approaches for osteomyelitis in people with sickle cell disease.

AUTHORS' CONCLUSIONS

We were unable to identify any relevant trials on the efficacy and safety of the antibiotic treatment approaches for people with sickle cell disease suffering from osteomyelitis. Randomised controlled trials are needed to establish the optimum antibiotic treatment for this condition, however, we do not envisage further trials of this intervention will be conducted, and hence the review will no longer be regularly updated.

Antibiotics for treating osteomyelitis in people with sickle cell disease

BACKGROUND

Osteomyelitis (both acute and chronic) is one of the most common infectious complications in people with sickle cell disease. There is no standardized approach to antibiotic therapy and treatment is likely to vary from country to country. Thus, there is a need to identify the efficacy and safety of different antibiotic treatment approaches for people with sickle cell disease suffering from osteomyelitis. This is an update of a previously published Cochrane Review.

OBJECTIVES

To determine whether an empirical antibiotic treatment approach (monotherapy or combination therapy) is effective and safe as compared to pathogen-directed antibiotic treatment and whether this effectiveness and safety is dependent on different treatment regimens, age or setting.

SEARCH METHODS

We searched The Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to 20 October 2016), African Index Medicus (20 October 2016), ISI Web of Knowledge (20 October 2016) and World Health Organization International Clinical Trials Registry Platform (20 October 2016).Date of most recent search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register: 18 August 2016.

SELECTION CRITERIA

We searched for published or unpublished randomised and quasi-randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data and assess trial quality by standard Cochrane methodologies, but no eligible randomised controlled trials were identified.

MAIN RESULTS

This update was unable to find any randomised or quasi-randomised controlled trials on antibiotic treatment approaches for osteomyelitis in people with sickle cell disease.

AUTHORS' CONCLUSIONS

We were unable to identify any relevant trials on the efficacy and safety of the antibiotic treatment approaches for people with sickle cell disease suffering from osteomyelitis. Randomised controlled trials are needed to establish the optimum antibiotic treatment for this condition.

Antibiotics for treating acute chest syndrome in people with sickle cell disease

BACKGROUND

The clinical presentation of acute chest syndrome is similar whether due to infectious or non-infectious causes, thus antibiotics are usually prescribed to treat all episodes. Many different pathogens, including bacteria, have been implicated as causative agents of acute chest syndrome. There is no standardized approach to antibiotic therapy and treatment is likely to vary from country to country. Thus, there is a need to identify the efficacy and safety of different antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome. This is an update of a Cochrane review first published in 2007, and previously updated in 2013.

OBJECTIVES

To determine whether an empirical antibiotic treatment approach (used alone or in combination):1. is effective for acute chest syndrome compared to placebo or standard treatment;2. is safe for acute chest syndrome compared to placebo or standard treatment;Further objectives are to determine whether there are important variations in efficacy and safety:3. for different treatment regimens,4. by participant age, or geographical location of the clinical trials.

SEARCH METHODS

We searched The Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to 23 February 2015), African Index Medicus (1982 to 23 February 2015). and the World Health Organization International Clinical Trials Registry Platform Search Portal (23 February 2015).Date of most recent search of the Haemoglobinopathies Trials Register: 20 January 2015.

SELECTION CRITERIA

We searched for published or unpublished randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data and assess trial quality by standard Cochrane Collaboration methodologies, but no eligible randomised controlled trials were identified.

MAIN RESULTS

For this update, we were unable to find any randomised controlled trials on antibiotic treatment approaches for acute chest syndrome in people with sickle cell disease.

AUTHORS' CONCLUSIONS

This update was unable to identify randomised controlled trials on efficacy and safety of the antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome. Randomised controlled trials are needed to establish the optimum antibiotic treatment for this condition.

Interventions for treating leg ulcers in people with sickle cell disease

BACKGROUND

The frequency of skin ulceration makes it an important contributor to the morbidity burden in people with sickle cell disease. Many treatment options are available to the healthcare professional, although it is uncertain which treatments have been assessed for effectiveness in people with sickle cell disease.

OBJECTIVES

To assess the clinical effectiveness and safety of interventions for treating leg ulcers in people with sickle cell disease.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register.We searched LILACS (1982 to August 2012), the African Index Medicus (up to August 2012), ISI Web of Knowledge (1985 to August 2012), and the Clinical Trials Search Portal of the World Health Organization (August 2012). We checked the reference lists of all the trials identified. We also contacted those groups or individuals who may have completed relevant randomised trials in this area.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register: 21 July 2014; date of the last search of the Cochrane Wounds Group Trials Register: 18 September 2014.

SELECTION CRITERIA

Randomised controlled trials of interventions for treating leg ulcers in people with sickle cell disease compared to placebo or an alternative treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion. All three authors independently assessed the risk of bias of the included studies and extracted data.

MAIN RESULTS

Six studies met the inclusion criteria (198 participants with 250 ulcers). Each trial investigated a different intervention and within this review we have grouped these as systemic pharmaceutical interventions (L-cartinine, arginine butyrate, isoxsuprine) and topical pharmaceutical interventions (Solcoseryl(®) cream, RGD peptide dressing, topical antibiotics). Three interventions reported on the change in ulcer size (arginine butyrate, RGD peptide, L-cartinine). Of these, RGD peptide matrix significantly reduced ulcer size compared with a control group, mean reduction 6.60cm(2) (95% CI 5.51 to 7.69; very low quality of evidence). Three trials reported on the incidence of complete closure (isoxsuprine, arginine butyrate, RGD peptide matrix; ranging between low and very low quality of evidence). None reported a significant effect. No trial reported on: the time to complete ulcer healing; ulcer-free survival following treatment for sickle cell leg ulcers; quality of life measures; or incidence of amputation. There was no reported information on the safety of these interventions.

AUTHORS' CONCLUSIONS

There is evidence that a topical intervention (RGD peptide matrix) reduced ulcer size in treated participants compared to controls. This evidence of efficacy is limited by the generally high risk of bias associated with these reports.We planned to analyse results according to general groups: pharmaceutical interventions (systemic and topical); and non-pharmaceutical interventions (surgical and non-surgical). However, we were unable to pool findings due to the heterogeneity in outcome definitions, and inconsistency between the unit of randomisation and the unit of analysis. This heterogeneity, along with a paucity of identified trials, prevented us performing any meta-analyses.This Cochrane review provides some evidence for the effectiveness of one topical intervention - RGD peptide matrix. However, this intervention was assessed as having a high risk of bias due to inadequacies in the single trial report. Other included studies were also assessed as having a high risk of bias. We recommend that readers interpret the trial results with caution. The safety profile of the all interventions was inconclusive.

Intravenous magnesium for pediatric sickle cell vaso-occlusive crisis: methodological issues of a randomized controlled trial

Multiple recent Sickle Cell Disease studies have been terminated due to poor enrollment. We developed methods to overcome past barriers and utilized these to study the efficacy and safety of intravenous magnesium for vaso-occlusive crisis (VOC). We describe the methods of the Intravenous Magnesium in Sickle Vaso-occlusive Crisis (MAGiC) trial and discuss methods used to overcome past barriers. MAGiC was a multi-center randomized double-blind placebo-controlled trial of intravenous magnesium versus normal saline for treatment of VOC. The study was a collaboration between Pediatric Hematologists and Emergency Physicians in the Pediatric Emergency Care Applied Research Network (PECARN). Eligible patients were randomized within 12 hours of receiving intravenous opioids in the Emergency Department (ED) and administered study medication every 8 hours. The primary outcome was hospital length of stay. Associated plasma studies elucidated magnesium's mechanism of action and the pathophysiology of VOC. Health-related quality of life was measured. Site-, protocol-, and patient-related barriers from prior studies were identified and addressed. Limited study staff availability, lack of collaboration with the ED, and difficulty obtaining consent were previously identified barriers. Leveraging PECARN resources, forging close collaborations between Sickle Cell Centers and EDs of participating sites, and approaching eligible patients for prior consent helped overcome these barriers. Participation in the PECARN network and establishment of collaborative arrangements between Sickle Cell Centers and their affiliated EDs are major innovative features of the MAGiC study that allowed improved subject capture. These methods could serve as a model for future studies of VOCs.

Sickle cell disease: acute clinical manifestations in early childhood and molecular characteristics in a group of children in Rio de Janeiro

Objectives

To describe clinical events of sickle cell disease and the correlation with β-globin haplotypes and α-thalassemia in under 6-year-old children.

Methods

A retrospective study was conducted of under 6-year-old children from the neonatal screening program in Rio de Janeiro. Forty-eight male and 48 female children were enrolled in this study, 79 with sickle cell anemia and 17 with hemoglobin SC. The mean age was 29.9 (standard deviation = 20.9) months, 62 (16.2 ± 8.6) were aged between 0-3 years old and 34 (54.9 ± 11.3) were from 3-6 years old. Painful events, acute splenic sequestration, hemolytic crises, hand-foot and acute chest syndromes and infections were evaluated.

Results

The events were more frequent in under 3-year-old children, 94% of children had at least one episode. Infection was the most common event affecting 88.5% of children. Acute splenic sequestration took place earlier, while painful crises and acute chest syndromes in under 6-year-old children. Thal-α 3.7 was observed in 20.9% of cases. Bantu was the most frequent haplotype found, followed by Benin. No correlation was observed between clinical events and β-globin haplotypes. Children with sickle cell anemia and α-thalassemia have less infectious events. No correlation was found among these polymorphisms and clinical events, however, the majority of children with Bantu/Bantu and without α-thalassemia had more clinical events.

Upper airway lymphoid tissue size in children with sickle cell disease

BACKGROUND

The prevalence of obstructive sleep apnea syndrome (OSAS) is higher in children with sickle cell disease (SCD) as compared with the general pediatric population. It has been speculated that overgrowth of the adenoid and tonsils is an important contributor.

METHODS

The current study used MRI to evaluate such an association. We studied 36 subjects with SCD (aged 6.9 ± 4.3 years) and 36 control subjects (aged 6.6 ± 3.4 years).

RESULTS

Compared with control subjects, children with SCD had a significantly smaller upper airway (2.8 ± 1.2 cm(3) vs 3.7 ± 1.6 cm(3), P < .01), and significantly larger adenoid (8.4 ± 4.1 cm(3) vs 6.0 ± 2.2 cm(3), P < .01), tonsils (7.0 ± 4.3 cm(3) vs 5.1 ± 1.9 cm(3), P < .01), retropharyngeal nodes (3.0 ± 1.9 cm(3) vs 2.2 ± 0.9 cm(3), P < .05), and deep cervical nodes (15.7 ± 5.7 cm(3) vs 12.7 ± 4.0 cm(3), P < .05). Polysomnography showed that 19.4% (seven of 36) of children with SCD had OSAS compared with 0% (zero of 20) of control subjects (P < .05) and that in children with SCD the apnea-hypopnea index correlated positively with upper airway lymphoid tissues size (r = 0.57, P < 001). In addition, children with SCD had lower arterial oxygen saturation nadir (84.3% ± 12.3% vs 91.2% ± 4.2%, P < .05), increased peak end-tidal CO(2) (53.4 ± 8.5 mm Hg vs 42.3 ± 5.3 mm Hg, P < .001), and increased arousals (13.7 ± 4.7 events/h vs 10.8 ± 3.8 events/h, P < .05).

CONCLUSIONS

Children with SCD have reduced upper airway size due to overgrowth of the surrounding lymphoid tissues, which may explain their predisposition to OSAS.

Carbon-fiber microelectrode amperometry reveals sickle-cell-induced inflammation and chronic morphine effects on single mast cells

Sickle cell disease, caused by a mutation of hemoglobin, is characterized by a complex pathophysiology including an important inflammatory component. Mast cells are tissue-resident leukocytes known to influence a range of immune functions in a variety of different ways, largely through the secretion of biologically active mediators from preformed granules. However, it is not understood how mast cells influence the inflammatory environment in sickle cell disease. A notable consequence of sickle cell disease is severe pain. Therefore, morphine is often used to treat this disease. Because mast cells express opioid receptors, it is pertinent to understand how chronic morphine exposure influences mast cell function and inflammation in sickle cell disease. Herein, carbon-fiber microelectrode amperometry (CFMA) was used to monitor the secretion of immunoactive mediators from single mast cells. CFMA enabled the detection and quantification of discrete exocytotic events from single mast cells. Mast cells from two transgenic mouse models expressing human sickle hemoglobin (hBERK1 and BERK) and a control mouse expressing normal human hemoglobin (HbA-BERK) were monitored using CFMA to explore the impact of sickle-cell-induced inflammation and chronic morphine exposure on mast cell function. This work, utilizing the unique mechanistic perspective provided by CFMA, describes how mast cell function is significantly altered in hBERK1 and BERK mice, including decreased serotonin released compared to HbA-BERK controls. Furthermore, morphine was shown to significantly increase the serotonin released from HbA-BERK mast cells and demonstrated the capacity to reverse the observed sickle-cell-induced changes in mast cell function.

Higher rates of hemolysis are not associated with albuminuria in Jamaicans with sickle cell disease

BACKGROUND

Albuminuria is a marker of glomerular damage in Sickle Cell Disease (SCD). In this study, we sought to determine the possible predictors of albuminuria in the two more prevalent genotypes of SCD among the Jamaica Sickle Cell Cohort Study participants.

METHODS

An age-matched cohort of 122 patients with HbSS or HbSC genotypes had measurements of their morning urine albumin concentration, blood pressure, body mass index, haematology and certain biochemistry parameters done. Associations of albuminuria with possible predictors including hematological parameters, reticulocyte counts, aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels were examined using multiple regression models.

RESULTS

A total of 122 participants were recruited (mean age 28.6 years ±2.5 years; 85 HbSS, 37 HbSC). 25.9% with HbSS and 10.8% with HbSC disease had microalbuminuria (urine albumin/creatinine ratio  =  30-300 mg/g of creatinine) whereas 16.5% of HbSS and 2.7% of HbSC disease had macroalbuminuria (urine albumin/creatinine ratio>300 mg/g of creatinine). Mean arterial pressure, hemoglobin levels, serum creatinine, reticulocyte counts and white blood cell counts were statistically significant predictors of albuminuria in HbSS, whereas white blood cell counts and serum creatinine predicted albuminuria in HbSC disease. Both markers of chronic hemolysis, i.e. AST and LDH levels, showed no associations with albuminuria in either genotype.

CONCLUSIONS

Renal disease, as evidenced by excretion of increased amounts of albumin in urine due to a glomerulopathy, is a common end-organ complication in SCD. It is shown to be more severe in those with HbSS disease than in HbSC disease. Rising blood pressure, lower hemoglobin levels and higher white blood cell counts are hints to the clinician of impending renal disease, whereas higher rates of hemolysis do not appear to play a role in this complication of SCD.