Efficacy and safety of pharmacological interventions for managing sickle cell disease in children and adolescents: protocol for a systematic review with network meta-analysis

IntroductionSickle cell disease (SCD), an inherited haemoglobinopathy, has important impact on morbidity and mortality, especially in paediatrics. Previous systematic reviews are limited to adult patients or focused only on few therapies. We aim to synthesise the evidence on efficacy and safety of pharmacological interventions for managing SCD in children and adolescents.Methods and analysisThis systematic review protocol is available at Open Science Framework (doi:10.17605/OSF.IO/CWAE9). We will follow international recommendations on conduction and report of systematic reviews and meta-analyses. Searches will be conducted in PubMed, Scopus and Web of Science (no language nor time restrictions) (first pilot searches performed in May 2022). We will include randomised controlled trials comparing the effects of disease-modifying agents in patients with SCD under 18 years old. Outcomes of interest will include: vaso-occlusive crisis, haemoglobin levels, chest syndrome, stroke, overall survival and adverse events. We will provide a narrative synthesis of the findings, and whenever possible, results will be pooled by means of pairwise or Bayesian network meta-analyses with surface under the cumulative ranking curve analyses. Different statistical methods and models will be tested. Dichotomous outcomes will be reported as OR, risk ratio or HR, while continuous data will be reported as standard mean differences, both with 95% CI/credibility interval. The methodological quality of the trials will be evaluated using the Risk of Bias 2.0 tool, and the certainty of the evidence will be assessed with the Grading of Recommendations Assessment, Development and Evaluation approach.Ethics and disseminationThis study refers to a systematic review, so no ethics approval is necessary. We intent to publish our findings in international, peer-reviewed journal. Data will also be presented to peers in scientific events. Additionally, the results obtained in this study may contribute towards the update of therapeutic guidelines and for the development of health policies for SCD.PROSPERO registration numberCRD42022328471.</jats:sec

The effect of hydroxyurea in the gut microbiome of Angolan children with sickle cell disease

FCT/Aga Khan (project nº330842553).FCT_UIDB/05608/2020. FCT_UIDP/05608/2020.Purpose: Sickle cell disease (SCD) is one of the most prevalent genetic disorders, affecting around 20 to 25 million individuals throughout the world. In Sub-Saharan Africa, where it is more prevalent, it can contribute to up to 80% of under-5 mortality. Clinical manifestations of SCD are very heterogeneous and the intestinal microbiome has recently been reported to be crucial in the modulation of inflammation, cell adhesion, and induction of aged neutrophils, which are key interveners of recurrent vaso-occlusive crises. Since gut bacteria can regulate aged neutrophils, defects in either the integrity of the intestinal walls or a chronic disequilibrium of the microbiota are very likely to emerge in SCD patients. Moreover, it has been suggested that Hydroxyurea (HU), the most common treatment for SCD, shows a multimodal action and may reduce microbiome dysbiosis and aged neutrophils. In this context, we aimed to understand how SCD and HU treatment modulates the microbiome and if these changes could be related to disease severity.info:eu-repo/semantics/publishedVersio

5595849 THE GUT MICROBIOME AND HYDROXYUREA EFFECT ON SICKLE CELL DISEASE CHILDREN FROM ANGOLA

This work was supported by FCT/Aga Khan (project nº330842553) and FCT/MCTES (UIDB/05608/2020 and UIDP/05608/2020) – H&TRC.Background: Sickle cell disease (SCD) is an inherited hematological disorder and a serious global health problem, affecting between 20 and 25 million people worldwide. In Sub-Saharan Africa, where it is more prevalent, it contributes up to 90% of under-5 mortality. Although hydroxyurea (HU) is the leading treatment for these patients, its effects on the gut microbiome have not yet been explored. Some studies reported that gastroenteritis events were less frequent in SCA children taking HU and it also significantly improved the survival from pneumococcal infections. HU may have a protective effect, not only by improving several hematological parameters but also by lowering the risk of some bacterial infections. Aims: In this context, the aim of this study was to investigate this association by characterizing the gut microbiome of an Angolan SCA pediatric population before and after 6 months of HU treatment and comparing it with a control group of healthy siblings. Results: A total of 113 fecal samples were obtained and sequenced by NGS for the 16S rRNA gene (V3-V4 regions), which corresponded to 40 children in the control and before HU groups and 33 after HU, aged between 4-12 years old. Our findings revealed that these three groups exhibit some notable differences, especially within Lachnospiraceae and Ruminococcaceae family. After HU treatment there was an increase of several beneficial bacteria, such as: Blautia coccoides (p=0.009), Blautia luti (p<0.001), Blautia faecis (p=0.008), Bifidobacterium longum (p=0.011), Dorea formicigenerans (p<0.001), Dorea massiliensis (p=0.003), Eubacterium halii (p=0.004), Elusimicrobium spp (p=0.032), Ruminococcus callidus (p=0.037), Ruminococcus faecis (p=0.012), Roseburia spp (p=0.050) and Subdoligranulum variabile (p=0.009). Most of those OTUs are SCFAs producing species, having butyrate or propionate as end-products of bacterial metabolism, both exhibiting anti-inflammatory properties. Moreover, children before HU had a higher abundance of bacteria considered pathogenic, like E. coli (p=0.001), Clostridiun_g24 (p=0.039), and H. influenzae (p=0.050). Conclusion: Overall, this study provides the first evidence of the HU effect on the gut microbiome and provides a rationale for further research for developing treatments to reduce gut microbiota-driven inflammation, which may attenuate the dysbiosis and chronic symptoms experienced by these patients.info:eu-repo/semantics/publishedVersio

5588995 COMPARATIVE EFFICACY AND SAFETY OF PHARMACOLOGICAL INTERVENTIONS FOR SICKLE CELL DISEASE IN CHILDREN AND ADOLESCENTS: A NETWORK META-ANALYSIS

Background: Sickle cell disease (SCD), an inherited hemoglobinopathy characterized by anemia, severe pain, acute chest syndrome (ACS), and vaso-occlusive crisis (VOC), has an important impact on morbidity and mortality worldwide, especially in the pediatric population (over 50% die before age of 5). Although few treatment options are available, new disease-modifying therapies, intended to prevent or reduce SCD-related complications are under development. Previous systematic reviews are limited to adult patients or focused only on gathering data on a few therapies. Aims: Our aim was to synthetize the evidence on the efficacy and safety profiles of pharmacological interventions for managing SCD in children and adolescents. Methods: A systematic review with searches in PubMed, Scopus, and Web of Science was performed (May-2022). The protocol is registered at PROSPERO CRD42022328471. We included randomized controlled trials comparing any disease-modifying agent used to treat SCD complications in patients under 18 years old. The outcomes of interest included: VOC, ACS, transfusions, hospital admission, discontinuation, and serious adverse events. Data were pooled by means of Bayesian network meta-analyses with the surface under the cumulative ranking curve analyses (SUCRA). Results were reported as odds ratio (OR) with 95% credibility intervals (CrI). Additionally, stochastic multicriteria acceptability analyses (SMAA) were performed. The methodological quality of the trials and certainty of evidence were evaluated through RoB 2.0 tool and the GRADE approach, respectively. Results: Overall, 17 randomized controlled trials (n=1,972 patients) published between 1982-2022, conducted mostly in Africa (41%) and North America (35%) were included for analyses. Around one-third of the trials were restricted to homozygous patients for the SCD allele (SS HMZ); yet when reported, patients with heterozygous S-C combination represented less than 30% of the population. Males accounted for 49.0% of the cases, with ages varying from 1 to 19 years old. Almost all trials (n=15, 88.2%) directly compared active drugs with placebo. The evaluated interventions were: hydroxyurea [n=6 trials], L-arginine [n=3], antiplatelets [n=2], immunotherapy/monoclonal antibodies [n=2], sulfates [n=2], docosahexaenoic acid [n=1], niprisan [n=1] (Figure 1). SUCRA and SMAA revealed that immunotherapy/monoclonal antibodies and hydroxyurea 20 mg/kg are potentially more effective against ACS (17% and 24% probabilities, respectively), VOC (around 29% and 20%, respectively) and needing of transfusions (around 25%), while L-arginine (100-200 mg/kg) and placebo were more associated with these events. Although therapies were overall considered safe, antiplatelet and sulfates may lead to more discontinuations and severe adverse events (uncertainty evidence). Results were similar between age subgroups (<10 years vs. 10-19 years). Summary - Conclusion: The available evidence on the effect of drugs on managing SCD in children and adolescents is still insufficient and weak. No clear definition and reporting criteria for some outcomes exist. Hydroxyurea 20 mg/kg/day may remain the standard of care for these patients, however, long-term, well-designed trials comparing new immunotherapy/monoclonal antibodies should be performed. The use of monotherapies with L-arginine, antiplatelets, or sulfates should be avoided given the poor benefit-risk ratio for this population.info:eu-repo/semantics/publishedVersio

5589865 PRELIMINARY FINDINGS FROM THE FOLLOW-UP OF PREGNANT SICKLE CELL DISEASE PATIENTS IN LUANDA, ANGOLA.

Background: In Angola, the prevalence of Sickle Cell Disease (SCD) is almost 2%, and the carriers reach 21% of the population. Although its presentation tends to be very heterogeneous, chronic hemolytic anemia, frequent painful crises, and extensive organ damage are common features of these patients. Pregnancy in SCD patients is associated with an increase in severe outcomes, namely, a high risk of eclampsia and pre-eclampsia, stroke, and even death. Therefore, it is crucial to maintain continuous medical surveillance during pregnancy, especially in women with previous strokes. Moreover, health services in low- and middle-income countries are generally not prepared to follow these patients. Aims: We aim to present the preliminary findings from the cohort study conducted at the Lucrecia Paim Maternity Hospital (Luanda, Angola), which aims to determine pregnancy complications in SCD women, especially those responsible for maternal death, and, by supporting the obstetric consultations in this hospital, contribute to the reduction of mortality and morbidity rates. Methods: Pregnancy monitoring includes analysis of clinical history and incidents (number of hospitalizations, blood transfusions, strokes, and other clinical complications), hematological and biochemical analysis, transcranial Doppler to assess cerebral hemodynamics and genetic analysis (confirmation of the diagnosis, genotyping of four SNPs in the β-cluster to assess the haplotype, and evaluation of the presence of the 3.7kb deletion of the α-globin gene). Results: To date, 61 women are being followed in the obstetric consultations, with ages from 18 to 40 years old (mean 26.1±5.4). There are no records of previous strokes, although 83.9% of the patients have been previously transfused (47 out of 56), 98.2% have been hospitalized (55 out of 56) due to SCD complications and 19.6% (10 out of 54) had at least one miscarriage. At the first appointment, total hemoglobin values ranged from 4.70 to 10.40 g/dL (n=52, mean 7.18±1.30), erythrocytes from 1.46 to 5.42 x1012/L (n=52, mean 2.46±0,72), white blood cells count from 1.67 to 61.88 x109/L (n=51, mean 12.20±8.69), platelets from 24.2 to 710.0 x109/L (n=52, mean 272.2±155.9), and lactate dehydrogenase (LDH) from 263.3 to 2836.7 (n=50, mean 708.1±450.46). The CAR/CAR haplotype, which is usually associated with a more severe prognosis, is the most prevalent in this population (57.7%, 30 out of 52), followed by the CAR/SEN haplotype (25.0%, 13 out of 52). In this population, 17.3% (9 out of 52) are homozygous for the 3.7kb α-thalassemia deletion and 44.2% (23 out of 52) are carriers. This deletion influences hematological and clinical aspects of sickle cell disease patients, resulting in less severe phenotypes. TCD time-averaged mean of the maximum velocity (TAMMx) at the middle cerebral arteries ranged between 41 to 132 cm/s (n=61, mean 84cm/s), and peak systolic velocity (PSV) from 61 to 180 cm/s (mean 129 cm/s). At the basilar artery level, TAMMx obtained were between 29 to 102 cm/s (n=60, mean 52 cm/s) and PSV ranged from 43 to 141 cm/s (mean 78 cm/s). Summary - Conclusion: The main goal of this project is to study pregnancy-related complications and outcomes by giving support to an Angolan cohort of SCD pregnant women. We also intend to obtain TCD reference values of cerebral blood flow velocities in pregnant women with SCD as a risk predictor of vascular events as there are no values in the literature for this specific population.info:eu-repo/semantics/publishedVersio