Hydroxyurea for the treatment of sickle cell disease: efficacy, barriers, toxicity, and management in children

Utilization and Perceptions of Hydroxyurea Therapy Among Adult Patients With Sickle Cell Disease in Al Ahsa, Saudi Arabia: A Cross-Sectional Study

BACKGROUND

Sickle cell disease (SCD) is a prevalent genetic disorder characterized by abnormal hemoglobin formation, resulting in severe complications. Hydroxyurea (HU) therapy has demonstrated efficacy in reducing SCD-related complications; however, its utilization patterns and patient perceptions remain underexplored, particularly in the Al Ahsa region of Saudi Arabia.

OBJECTIVE

This cross-sectional study aimed to assess the prevalence of HU usage among adult patients with SCD in Al Ahsa; identify the barriers to starting, maintaining, and discontinuing HU therapy; and evaluate the patient-reported outcomes associated with its use.

METHODS

Data were collected through face-to-face surveys and medical record reviews of adult SCD patients attending outpatient clinics in the Hereditary Blood Diseases Center of Al Ahsa, Saudi Arabia, between December 2023 and March 2024. Descriptive statistics and inferential analyses were performed using SPSS version 26.

RESULTS

A total of 345 adult SCD patients were included, with a mean age of 34.12 ± 11.1 years. Most participants were male (58.6%) and unmarried (55.4%). HU utilization was reported by 57.1% of the participants, with the highest adherence observed among older age groups (p = 0.001). Significant improvements in pain severity, hospitalization rates, and quality of life were reported among HU users (p < 0.001). Common barriers to HU use included concerns about side effects, lack of medical justification, and absence of medical advice.

CONCLUSION

This study provides valuable insights into the utilization and perceptions of HU therapy among adults with SCD in Al Ahsa, Saudi Arabia. Addressing identified barriers and promoting patient education are crucial for optimizing therapy adherence and improving clinical outcomes in this population.

Managing gastrointestinal challenges: Diarrhea in sickle cell anemia

Sickle cell anemia (SCA), a hereditary hemoglobinopathy, is characterized by the presence of abnormal hemoglobin and has long been associated with a wide range of complications. While much attention has been given to the condition hematological aspects, gastrointestinal complications, particularly diarrhea, have been relatively understudied and often overlooked. This publication delves into the management of gastrointestinal challenges, with a focus on diarrhea, in individuals living with SCA. The pathophysiology of SCA is intrinsically linked to gastrointestinal complications, and diarrhea is a common manifestation of this condition. This abstract publication outlines the key elements discussed in the full-length work, which includes the clinical presentation of diarrhea in these patients, the diagnostic tools used to evaluate the condition, and various management strategies to alleviate symptoms and enhance the overall quality of life for affected individuals. The paper emphasizes the importance of patient education, offering healthcare professionals valuable insights into how to inform and support patients in managing their conditions effectively. It also highlights the need for continued research to further our understanding of gastrointestinal challenges in SCA and to identify potential areas for future therapeutic interventions. Ultimately, the comprehensive management of diarrhea in individuals with SCA is vital for their overall well-being. This publication serves as a valuable resource for healthcare providers, researchers, and caregivers in addressing the gastrointestinal challenges that accompany SCA, ultimately working toward a better quality of life for those affected by this condition.

Adherence to Hydroxyurea and Patients' Perceptions of Sickle Cell Disease and Hydroxyurea: A Cross-Sectional Study

Background and Objectives: Hydroxyurea is a crucial treatment for sickle cell disease (SCD), but some patients' adherence to it remains suboptimal. Understanding patients' perspectives on SCD and HU is essential for improving adherence. This study aimed to assess hydroxyurea adherence and patients' perceptions of SCD and hydroxyurea among SCD patients in the Jazan region of Saudi Arabia. Materials and Methods: This cross-sectional study collected data from 217 SCD patients using self-administered questionnaires from August 2022 to January 2023. The survey covered patient demographics, SCD consequences, and other clinical data. We used the Brief Illness Perception Questionnaire (B-IPQ) to measure patients' disease perception and the 8-item Morisky Medication Adherence Scale (MMAS-8) to evaluate patients' adherence to HU. Data were analysed using descriptive, t-test, and chi-square tests, and the p-value was set at <0.05 for significance. Results: More than half of the patients were male, with a mean age of 28.09 ± 8.40 years. About 57.6% of the patients were currently using HU. About 81.6% of HU users reported low adherence. The adherence was lower among individuals with infections/recurrent infections and in patients who received repeated blood transfusions. ICU admission, blood transfusion, and certain SCD complications were associated with HU use. Male patients had a higher perception of SCD consequences, concern, and understanding. ICU-admitted and recurrent hospitalized patients had a higher perception of the SCD-related consequences, symptoms, concerns, and emotional responses. Conclusions: HU seems a well-established and efficacious disease-modifying agent, but its underutilization for SCD patients remains challenging. To overcome the adherence challenges, healthcare providers must educate SCD patients about the role of hydroxyurea in lowering disease severity and addressing side effects to obtain maximum benefits. Healthcare providers may consider tailored educational interventions to improve adherence, particularly for patients with infections, recurrent hospitalizations, or repeated blood transfusions. Further research is needed to identify strategies for improving hydroxyurea adherence and patient education among SCD patients.

Management of Acute Sickle Cell Disease Pain

Pain is a common complication of sickle cell disease. Sickle cell pain can often be effectively managed by pediatricians in outpatient and hospital settings. Acute pain management should be initiated quickly. Patients need to be evaluated for sickle cell complications and other causes of pain. Nonsteroidal anti-inflammatory drugs and opioids are the mainstay of pain treatment, but additional therapies include hydration, local pain control, muscle relaxants, and nonpharmacologic approaches. Healthy lifestyle habits and good behavioral and mental health are important for preventing and coping with sickle cell disease pain. Disease-modifying therapies, such as hydroxyurea, can help prevent sickle hemoglobin polymerization and acute pain episodes. Because sickle cell disease largely affects people who are racialized minorities in the United States, health-care providers need to be aware of how their own personal biases may affect care of these patients.

Provider prescription of hydroxyurea in youth and adults with sickle cell disease: A review of prescription barriers and facilitators

Sickle cell disease (SCD) is an inherited red blood cell disorder associated with frequent painful events and organ damage. Hydroxyurea (HU) is the recommended evidence-based treatment of SCD. However, among patients eligible for HU, prescription rates are low. Utilizing a scoping review approach, we summarized and synthesized relevant findings regarding provider barriers and facilitators to the prescription of HU in youth and adults with SCD and provided suggestions for future implementation strategies to improve prescription rates. Relevant databases were searched using specified search terms. Articles reporting provider barriers and/or facilitators to prescribing HU were included. A total of 10 studies met the inclusion criteria. Common barriers to the prescription of HU identified by providers included: doubts around patients' adherence to HU and their engaging in required testing, concerns about side effects, lack of knowledge, cost and patient concerns about side effects. Facilitators to the prescription of HU included beliefs in the effectiveness of HU, provider demographics and knowledge. Findings suggest significant provider biases exist, particularly in the form of negative perceptions towards patients' ability to adhere to taking HU and engaging in the required follow-up. Improving provider knowledge and attitudes towards HU and SCD may help improve low prescription rates.

Hydroxyurea treatment for adult sickle cell anemia patients in Kinshasa

Background: Despite a high incidence of sickle cell anemia, hydroxyurea (HU) treatment is rarely used in the DR Congo. This study aims to assess the efficacy of HU, the incidence of side effects that may limit its use in adults and to determine the dose needed for clinical improvement in patients. Methods: In a prospective study, patients received an initial dose of 15 mg/kg/day which was increased by 5 mg/kg every 6 months, up to a maximum of 30 mg/kg/day. The response and side effects to HU were evaluated biologically and clinically every 3 months during a 2-year period. Results: Seventy adult patients with a moderate or severe clinical phenotype initiated treatment. Only minor side effects were reported. At the end of the 2-year treatment phase, 45 (64.3%) had dropped out, of whom 33 were without a clear reason. Clinical and biological improvement was more marked during the first year. There was a reduction in severe vaso-occlusive crises (p < 0.001), need for transfusion (p < 0.001), and hospitalization days (p = 0.038). Fetal hemoglobin (HbF) levels increased on average 2.9 times after 12 months (p < 0.001). The increase in mean corpuscular volume was greater in the first year (p < 0.001) than in the second year (p = 0.041). The decrease in leukocytes (p < 0.001) was significant during the first year. In 70% of patients, the 20 mg/kg/day dose was needed to reach the 20% HbF threshold. Conclusion: HU is effective and well tolerated. The magnitude of the response varies from one patient to another. Improvement of clinical manifestations is achieved in most patients with a relatively low dose. Effective implementation of HU treatment will require improved adherence to treatment.

Management of Older Adults with Sickle Cell Disease: Considerations for Current and Emerging Therapies

People with sickle cell disease (SCD) are living longer than ever before, with the median survival increasing from age 14 years in 1973, beyond age 40 years in the 1990s, and as high as 61 years in recent cohorts from academic centers. Improvements in survival have been attributed to initiatives, such as newborn screening, penicillin prophylaxis, vaccination against encapsulated organisms, better detection and treatment of splenic sequestration, and improved transfusion support. There are an estimated 100,000 people living with SCD in the United States and millions of people with SCD globally. Given that the number of older adults with SCD will likely continue to increase as survival improves, better evidence on how to manage this population is needed. When managing older adults with SCD (defined herein as age ≥ 40 years), healthcare providers should consider the potential pitfalls of extrapolating evidence from existing studies on current and emerging therapies that have typically been conducted with participants at mean ages far below 40 years. Older adults with SCD have historically had little to no representation in clinical trials; therefore, more guidance is needed on how to use current and emerging therapies in this population. This article summarizes the available evidence for managing older adults with SCD and discusses potential challenges to using approved and emerging drugs in this population.

Foetal haemoglobin inducers for reducing blood transfusion in non-transfusion-dependent beta-thalassaemias

BACKGROUND

Non-transfusion-dependent β-thalassaemia (NTDβT) is a subset of inherited haemoglobin disorders characterised by reduced production of the β-globin chain of haemoglobin leading to anaemia of varying severity. Although blood transfusion is not a necessity for survival, it may be required to prevent complications of chronic anaemia, such as impaired growth and hypercoagulability. People with NTDβT also experience iron overload due to increased iron absorption from food sources which becomes more pronounced in those requiring blood transfusion. People with a higher foetal haemoglobin (HbF) level have been found to require fewer blood transfusions, thus leading to the emergence of treatments that could increase its level. HbF inducers stimulate HbF production without altering any gene structures. Evidence for the possible benefits and harms of these inducers is important for making an informed decision on their use.

OBJECTIVES

To compare the effectiveness and safety of the following for reducing blood transfusion for people with NTDβT: 1. HbF inducers versus usual care or placebo; 2. single HbF inducer with another HbF inducer, and single dose with another dose; and 3. combination of HbF inducers versus usual care or placebo, or single HbF inducer.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 21 August 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs comparing single HbF inducer with placebo or usual care, with another single HbF inducer or with a combination of HbF inducers; or comparing different doses of the same HbF inducer.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were blood transfusion and haemoglobin levels. Our secondary outcomes were HbF levels, the long-term sequelae of NTDβT, quality of life and adverse events.

MAIN RESULTS

We included seven RCTs involving 291 people with NTDβT, aged two to 49 years, from five countries. We reported 10 comparisons using eight different HbF inducers (four pharmacological and four natural): three RCTs compared a single HbF inducer to placebo and seven to another HbF inducer. The duration of the intervention lasted from 56 days to six months. Most studies did not adequately report the randomisation procedures or whether and how blinding was achieved. HbF inducer against placebo or usual care Three HbF inducers, HQK-1001, Radix Astragali or a 3-in-1 combined natural preparation (CNP), were compared with a placebo. None of the comparisons reported the frequency of blood transfusion. We are uncertain whether Radix Astragali and CNP increase haemoglobin at three months (mean difference (MD) 1.33 g/dL, 95% confidence interval (CI) 0.54 to 2.11; 1 study, 2 interventions, 35 participants; very low-certainty evidence). We are uncertain whether Radix Astragali and CNP have any effect on HbF (MD 12%, 95% CI -0.74% to 24.75%; 1 study, 2 interventions, 35 participants; very low-certainty evidence). Only medians on haemoglobin and HbF levels were reported for HQK-1001. Adverse effects reported for HQK-1001 were nausea, vomiting, dizziness and suprapubic pain. There were no prespecified adverse effects for Radix Astragali and CNP. HbF inducer versus another HbF inducer Four studies compared a single inducer with another over three to six months. Comparisons included hydroxyurea versus resveratrol, hydroxyurea versus thalidomide, hydroxyurea versus decitabine and Radix Astragali versus CNP. No study reported our prespecified outcomes on blood transfusion. Haemoglobin and HbF were reported for the comparison Radix Astragali versus CNP, but we are uncertain whether there were any differences (1 study, 24 participants; low-certainty evidence). Different doses of the same HbF inducer Two studies compared two different types of HbF inducers at different doses over two to six months. Comparisons included hydroxyurea 20 mg/kg/day versus 10 mg/kg/day and HQK-1001 10 mg/kg/day, 20 mg/kg/day, 30 mg/kg/day and 40 mg/kg/day. Blood transfusion, as prespecified, was not reported. In one study (61 participants) we are uncertain whether the lower levels of both haemoglobin and HbF at 24 weeks were due to the higher dose of hydroxyurea (haemoglobin: MD -2.39 g/dL, 95% CI -2.80 to -1.98; very low-certainty evidence; HbF: MD -10.20%, 95% CI -16.28% to -4.12%; very low-certainty evidence). The study of the four different doses of HQK-1001 did not report results for either haemoglobin or HbF. We are not certain if major adverse effects may be more common with higher hydroxyurea doses (neutropenia: risk ratio (RR) 9.93, 95% CI 1.34 to 73.97; thrombocytopenia: RR 3.68, 95% CI 1.12 to 12.07; very low-certainty evidence). Taking HQK-1001 20 mg/kg/day may result in the fewest adverse effects. A combination of HbF inducers versus a single HbF inducer Two studies compared three combinations of two inducers with a single inducer over six months: hydroxyurea plus resveratrol versus resveratrol or hydroxyurea alone, and hydroxyurea plus l-carnitine versus hydroxyurea alone. Blood transfusion was not reported. Hydroxyurea plus resveratrol may reduce haemoglobin compared with either resveratrol or hydroxyurea alone (MD -0.74 g/dL, 95% CI -1.45 to -0.03; 1 study, 54 participants; low-certainty evidence). We are not certain whether the gastrointestinal disturbances, headache and malaise more commonly reported with hydroxyurea plus resveratrol than resveratrol alone were due to the interventions. We are uncertain whether hydroxyurea plus l-carnitine compared with hydroxyurea alone may increase mean haemoglobin, and reduce pulmonary hypertension (1 study, 60 participants; very low-certainty evidence). Adverse events were reported but not in the intervention group. None of the comparisons reported the outcome of HbF.

AUTHORS' CONCLUSIONS

We are uncertain whether any of the eight HbF inducers in this review have a beneficial effect on people with NTDβT. For each of these HbF inducers, we found only one or at the most two small studies. There is no information on whether any of these HbF inducers have an effect on our primary outcome, blood transfusion. For the second primary outcome, haemoglobin, there may be small differences between intervention groups, but these may not be clinically meaningful and are of low- to very low-certainty evidence. Data on adverse effects and optimal doses are limited. Five studies are awaiting classification, but none are ongoing.

Effective therapies for sickle cell disease: are we there yet?

Sickle cell disease (SCD) is a common genetic blood disorder associated with acute and chronic pain, progressive multiorgan damage, and early mortality. Recent advances in technologies to manipulate the human genome, a century of research and the development of techniques enabling the isolation, efficient genetic modification, and reimplantation of autologous patient hematopoietic stem cells (HSCs), mean that curing most patients with SCD could soon be a reality in wealthy countries. In parallel, ongoing research is pursuing more facile treatments, such as in-vivo-delivered genetic therapies and new drugs that can eventually be administered in low- and middle-income countries where most SCD patients reside.

Determinants of hydroxyurea use among doctors, nurses and sickle cell disease patients in Nigeria

Background

Hydroxyurea (HU) is an evidence-based therapy that is currently the most effective drug for sickle cell disease (SCD). HU is widely used in high-income countries with consequent reduction of morbidity and mortality. In Nigeria, HU is prescribed by physicians while nurses are mainly involved in counseling the patients to ensure adherence. The extent of utilization and the determinant factors have not been sufficiently evaluated in Nigeria.

Objective

To assess the frequency of use of HU and factors affecting utilization among healthcare providers, patients, and caregivers for SCD.

Methods

A questionnaire was administered online and in- person to assess the frequency of HU use and the factors that promote and limit its use. The data were analyzed by descriptive statistics using IBM SPSS software version 23 and the result was presented in frequency tables and percentages.

Result

A total of 137 physicians, 137 nurses, and 237 patients/caregivers responded to the survey. The rate of prescription of HU by doctors in the past 6 months was 64 (46.7%), 43 (31.4%) nurses provided counseling and 36 (15.6%) patients were on HU. Among doctors, adequate knowledge (91.3%), clinical benefits and safety (94.8%), and inclusion of HU in management guidelines (86.9%) were motivators for prescribing it while inadequate knowledge (60.9%) and unawareness of treatment guidelines (68.6%) constituted barriers. Among nurses, reduction of crisis (91.6%) and safety (64.8%) were the major motivators while barriers were high cost (79.1%) and intensive monitoring (63.1%) of HU treatment. Among the patients, the major motivator was the reduction of crises (80.3%) while poor knowledge (93.2%), high cost of the drug (92.2%) while monitoring (91.2%), non-availability (87.7%) and side effects (83.9%) were the major barriers for the utilization of HU.

Conclusion

HU prescription and utilization are still poor among healthcare providers and patients. Inadequate knowledge, non-availability and high cost of HU as well as unawareness of treatment guidelines constitute major barriers to prescription and utilization.

Stability evaluation of compounded hydroxyurea 100 mg/mL oral liquids using a novel analytical method involving chemical derivatization

This study assessed the stability of six extemporaneously compounded hydroxyurea oral liquids stored at room temperature. Hydroxyurea oral liquids (100 mg/mL) were prepared using three different mixing methods (mortar, mixer or QuartetRx) from either bulk powder, capsule content, or whole capsules. Two brands of capsules were tested in this study. All formulations were stored at room temperature (25°C / 60% RH) in amber plastic bottles for 90 days and amber plastic syringes for 14 days. Physical stability was assessed visually, while chemical stability was evaluated using a stability-indicating high-performance liquid chromatography method. Chemical derivatization with xanthydrol allowed the retention of hydroxyurea on a reverse-phase column. At least 93.9% and 97.0% of the initial concentration of hydroxyurea remained after 90 days in bottles and 14 days in syringes, respectively. There were no visual changes in formulations over the study period. Changes in pH up to 1.6 units were observed after 90 days of storage and were explained most likely by an ammonium generating degradation pathway. Ammonium was quantified and remained within safe levels in each HU 100 mg/mL oral preparations. Hydroxyurea oral liquids were all stable for 90 days in amber plastic bottles and 14 days in amber plastic syringes.

Elastographic evaluation of the effect of sickle cell anemia on testicles: a prospective study

To quantitatively determine testicular tissue stiffness values using shear wave elastography (SWE) in males that have sickle cell anemia (SCA) and to evaluate the relationship between elastography results and semen analysis parameters and hormone levels. Fifty patients diagnosed with SCA and followed up in the hematology outpatient clinic were evaluated in the urology outpatient clinic as the study group. In addition, there were 88 patients without any SCA-related complaints in the control group. We compared these groups with respect to their values, spermiogram parameters, testicular volume, and SWE values. Among patients in the SCA group, 28% had impaired sperm parameters. When testicular elastography was assessed, the testicular volumes were materially lower in the SCA group in comparison to the control group [right testicular volume: 14.76 (12.77-18.12) and 19.68 (15.12-24.18), respectively, p < 0.001; left testicular volume: 14.11 (11.06-17.32) and 16.59 (13.38-20.13), respectively, p = 0.015]. Additionally, the left testis central stiffness and the left testis inferior stiffness were significantly higher in the SCA group (p < 0.001 and p = 0.014, respectively). The age and hydroxyurea use had a worse effect on sperm parameters in patients with SCA (odds ratio: -0.161 and -1.914, standard deviation: 0.071 and 0.921, and p = 0.024 and p = 0.038, respectively). We consider that the technique utilized in this study for SWE values is fast and can be adopted as a reliable diagnostic tool and follow-up practice in routine clinical practice to evaluate the acuteness of damage to the testicles in patients having SCA.

Clinical-Epidemiological Characteristics and Mortality in Patients with Sickle Cell Anemia: A Retrospective Cohort Study of 1980 at 2018

PURPOSE

To analyze the clinical-epidemiological characteristics and mortality in patients with sickle-cell anemia (SCA).

PATIENTS AND METHODS

A cohort study with retrospective data, conducted in two reference hospitals for SCA treatment from January 1980 to December 2018, recorded in two reference services. With a 5% significance level, the Chi-Square and Student's t-tests were employed in the inferential statistical analysis.

RESULTS

A total of 128 patients with SCA were studied. Diagnosis up to the fifth day of life was made in 10 patients. There were 19 deaths, of which 12 (63.2%) were female, and the average age at death was 27.05 (± 14.78) years. The leading causes of death were septic shock and cardiogenic shock. The use of invasive medical devices was considered a risk factor for death (RR=2.63; 95% CI=1.16-5.96; p=0.018), and monitoring time up to 20 years presented a 31% reduction in the risk of dying (RR=0.31; 95% CI=0.12-0.82; p=0.011) when compared to the monitoring of more than 20 years.

CONCLUSION

These findings are to be considered in the treatment of patients with SCA, mainly regarding early diagnosis and access to the treatment immediately afterward, since they are fundamental in improving survival and reducing severe complications.

Development and Validation of the Patient/Caregiver Reported Hydroxyurea Evaluation of Adherence for Life (HEAL) Scale

INTRODUCTION

Hydroxyurea reduces the incidence of vaso-occlusive episodes, stroke, and respiratory, cardiac, and renal damage in sickle cell disease by increasing fetal hemoglobin. However, because suboptimal adherence to hydroxyurea limits its effectiveness, understanding patient-specific barriers to hydroxyurea adherence could help improve adherence and health outcomes in patients with sickle cell disease. The aim of this single-site, prospective, IRB-approved study was to validate a 24-item patient- and caregiver-reported hydroxyurea treatment adherence questionnaire, the Hydroxyurea Evaluation of Adherence for Life (HEAL) scale.

METHODS

A sample of 24 adults with sickle cell disease and 16 caregivers of children with sickle cell disease completed the HEAL scale, and a subset of the original sample provided a second HEAL scale for test-retest reliability. HEAL scale results were validated against global adherence ratings from participants and health-care providers, records of access to pill bottles, and laboratory values for fetal hemoglobin and absolute neutrophil count.

RESULTS AND DISCUSSION

Results demonstrated excellent internal consistency for the HEAL Total score and eight (3-item) subscale scores (Dose, Remember, Plan, Cost, Understand, Effectiveness, Laboratory, and Pharmacy), as well as strong test-retest reliability for all HEAL scores except the Cost subscale. HEAL Total scores correlated significantly with validity measures, including global adherence ratings and lab values. The HEAL scale offers significant clinical potential for understanding adherence in individual sickle cell disease patients and significant research potential for characterizing adherence in persons with sickle cell disease who are treated with hydroxyurea.

Cilostazol-mediated reversion of γ-globin silencing is associated with a high level of HbF production: A potential therapeutic candidate for β-globin disorders

Reversal of fetal hemoglobin (HbF) silencing is an attractive therapeutic intervention for β-thalassemia and sickle cell anemia. The current study proposes the therapeutic of repurposing of cilostazol, an FDA-approved antithrombotic agent, as a promising HbF inducer. Preliminary, we report that cilostazol induced erythroid differentiation and hemoglobinization of human erythroleukemia K562 cells. The erythroid differentiation was accompanied by increased expression of γ-globin mRNA transcripts and HbF production. Cilostazol induced erythroid differentiation and HbF production, without significantly affecting proliferation and viability of hemoglobin producing cells at maximum erythroid inducing concentration. Moreover, we investigated the effect of cilostazol on human β- and γ-globin transgenes in in vivo β-YAC transgenic mice, harboring human β-locus along with β-LCR. A good in vitro correlation was found with substantial up-regulation in fetal globin mRNA; whereas, the β-globin gene expression was not significantly changed. F-cells, analysis in the peripheral blood of cilostazol-treated mice, revealed a significant increase in the F-cells population as compared with sham control groups. Together, these findings support the potential of cilostazol as an HbF inducer, which can be evaluated further to develop a new HbF inducer.

Therapeutic Dose of Hydroxyurea-Induced Synaptic Abnormalities on the Mouse Spermatocyte

Hydroxyurea (HU) is a widely used pharmacological therapy for sickle cell disease (SCD). However, replication stress caused by HU has been shown to inhibit premeiotic S-phase DNA, leading to reproductive toxicity in germ cells. In this study, we administered the therapeutic doses of HU (i.e., 25 and 50 mg/kg) to male mice to explore whether replication stress by HU affects pachytene spermatocytes and causes the abnormalities of homologous chromosomes pairing and recombination during prophase I of meiosis. In comparison with the control group, the proportions of spermatocyte gaps were significantly different in the experimental groups injected with 25 mg/kg (p < 0.05) and 50 mg/kg of HU (p < 0.05). Moreover, the proportions of unrepaired double-stranded breaks (DSBs) observed by γH2AX staining also corresponded to a higher HU dose with a greater number of breaks. Additionally, a reduction in the counts of recombination foci on the autosomal SCs was observed in the pachytene spermatocytes. Our results reveal that HU has some effects on synaptonemal complex (SC) formation and DSB repair which suggest possible problems in fertility. Therefore, this study provides new evidence of the mechanisms underlying HU reproductive toxicity.

Intentional and unintentional nonadherence to hydroxyurea among people with sickle cell disease: a qualitative study

Hydroxyurea is an efficacious treatment for sickle cell disease (SCD), but adoption is low among individuals with SCD. The objective of this study was to examine barriers to patients' adherence to hydroxyurea use regimens by using the intentional and unintentional medication nonadherence framework. We interviewed individuals with SCD age 15 to 49.9 years who were participants in the Sickle Cell Disease Implementation Consortium (SCDIC) Needs Assessment. The intentional and unintentional medication nonadherence framework explains barriers to using hydroxyurea and adds granularity to the understanding of medication adherence barriers unique to the SCD population. In total, 90 semi-structured interviews were completed across 5 of the 8 SCDIC sites. Among interviewed participants, 57.8% (n = 52) were currently taking hydroxyurea, 28.9% (n = 26) were former hydroxyurea users at the time of the interview, and 13.3% (n = 12) had never used hydroxyurea but were familiar with the medication. Using a constructivist grounded theory approach, we discovered important themes that contributed to nonadherence to hydroxyurea, which were categorized under unintentional (eg, Forgetfulness, External Influencers) and intentional (Negative Perceptions of Hydroxyurea, Aversion to Taking Any Medications) nonadherence types. Participants more frequently endorsed adherence barriers that fell into the unintentional nonadherence type (70%) vs intentional nonadherence type (30%). Results from this study will help SCD health care providers understand patient choices and decisions as being either unintentional or intentional, guide tailored clinical discussions regarding hydroxyurea therapy, and develop specific, more nuanced interventions to address nonadherence factors.

Improvement of SCD morbimortality in children: experience in a remote area of an African country

BACKGROUND

Sickle cell disease (SCD) is a public health problem in the Democratic Republic of Congo. While reference sickle cell centers have been implemented in capital cities of African countries and have proven to be beneficial for SCD patients. In the Democratic Republic of Congo, they have never been set up in remote areas for families with low or very low sources of income.

METHOD

A cohort of 143 children with SCD aged 10 years old (IQR (interquartile range): 6-15 years) (sex ratio male/female = 1.3) were clinically followed for 12 months without any specific intervention aside from the management of acute events, and then for 12 months with a monthly medical visit, biological follow-up, and chemoprophylaxis (folic acid/penicillin), adequate fluids and malaria prevention.

RESULTS

The median age of patients at the diagnosis of SCD was 2 years (IQR: 1-5). The implementation of standardized and regular follow-ups in a new sickle cell reference center in a remote city showed an increase in the annual mean hemoglobin level from 50 to 70 g/L (p = 0.001), and a decrease in the lymphocyte count and spleen size (p < 0.001). A significant decrease (p < 0.001) in the average annual number of hospitalizations and episodes of vaso-occlusive crises, blood transfusions, infections, and acute chest syndromes were also observed.

CONCLUSIONS

The creation of a sickle cell reference center and the regular follow-up of children with sickle cell disease are possible and applicable in the context of a remote city of an African country and represent simple and accessible measures that can reduce the morbimortality of children with sickle cell disease.

Laser tweezers as a biophotonic tool to investigate the efficacy of living sickle red blood cells in response to optical deformation

A laser tweezer technique based on single and/or dual-laser beams is proposed as a biophotonic tool to trap single cells and investigate their biophysical and biomechanical characteristics. Optical deformability and changes in size and cellular morphology of living and nonliving cells can be measured using the proposed technique. Representative results of red blood cell (RBC) optical deformability of 20 homozygous patients with sickle cell disease, including follow-up patients after treating with hydroxyurea (HU) for at least 3 months and 20 healthy control groups, are presented and compared. Shape recovery of deformed RBCs and relaxation time are recorded for each RBC. Results showed that healthy blood and patients treated with HU demonstrate significantly higher optical deformability and degree of optical elongation with morphological change of RBCs than untreated patients. Moreover, the healthy control group and patients treated with HU exhibited faster relaxation time for RBCs than untreated patients. A trapping power that reaches 180 mW caused no observable photo-damage at a wavelength 1064 nm.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12551-021-00790-0.

Evidence-based interventions implemented in low-and middle-income countries for sickle cell disease management: A systematic review of randomized controlled trials

BACKGROUND

Despite ~90% of sickle cell disease (SCD) occurring in low-and middle-income countries (LMICs), the vast majority of people are not receiving evidence-based interventions (EBIs) to reduce SCD-related adverse outcomes and mortality, and data on implementation research outcomes (IROs) and SCD is limited. This study aims to synthesize available data on EBIs for SCD and assess IROs.

METHODS

We conducted a systematic review of RCTs reporting on EBIs for SCD management implemented in LMICs. We identified articles from PubMed/Medline, Global Health, PubMed Central, Embase, Web of Science medical subject heading (MeSH and Emtree) and keywords, published from inception through February 23, 2020, and conducted an updated search through December 24, 2020. We provide intervention characteristics for each study, EBI impact on SCD, and evidence of reporting on IROs.

MAIN RESULTS

29 RCTs were analyzed. EBIs identified included disease modifying agents, supportive care agents/analgesics, anti-malarials, systemic treatments, patient/ provider education, and nutritional supplements. Studies using disease modifying agents, nutritional supplements, and anti-malarials reported improvements in pain crisis, hospitalization, children's growth and reduction in severity and prevalence of malaria. Two studies reported on the sustainability of supplementary arginine, citrulline, and daily chloroquine and hydroxyurea for SCD patients. Only 13 studies (44.8%) provided descriptions that captured at least three of the eight IROs. There was limited reporting of acceptability, feasibility, fidelity, cost and sustainability.

CONCLUSION

EBIs are effective for SCD management in LMICs; however, measurement of IROs is scarce. Future research should focus on penetration of EBIs to inform evidence-based practice and sustainability in the context of LMICs.

CLINICAL TRIAL REGISTRATION

This review is registered in PROSPERO #CRD42020167289.

The Worst Things in Life are Free: The Role of Free Heme in Sickle Cell Disease

Hemolysis is a pathological feature of several diseases of diverse etiology such as hereditary anemias, malaria, and sepsis. A major complication of hemolysis involves the release of large quantities of hemoglobin into the blood circulation and the subsequent generation of harmful metabolites like labile heme. Protective mechanisms like haptoglobin-hemoglobin and hemopexin-heme binding, and heme oxygenase-1 enzymatic degradation of heme limit the toxicity of the hemolysis-related molecules. The capacity of these protective systems is exceeded in hemolytic diseases, resulting in high residual levels of hemolysis products in the circulation, which pose a great oxidative and proinflammatory risk. Sickle cell disease (SCD) features a prominent hemolytic anemia which impacts the phenotypic variability and disease severity. Not only is circulating heme a potent oxidative molecule, but it can act as an erythrocytic danger-associated molecular pattern (eDAMP) molecule which contributes to a proinflammatory state, promoting sickle complications such as vaso-occlusion and acute lung injury. Exposure to extracellular heme in SCD can also augment the expression of placental growth factor (PlGF) and interleukin-6 (IL-6), with important consequences to enthothelin-1 (ET-1) secretion and pulmonary hypertension, and potentially the development of renal and cardiac dysfunction. This review focuses on heme-induced mechanisms that are implicated in disease pathways, mainly in SCD. A special emphasis is given to heme-induced PlGF and IL-6 related mechanisms and their role in SCD disease progression.

In utero Therapy for the Treatment of Sickle Cell Disease: Taking Advantage of the Fetal Immune System

Sickle Cell Disease (SCD) is an autosomal recessive disorder resulting from a β-globin gene missense mutation and is among the most prevalent severe monogenic disorders worldwide. Haematopoietic stem cell transplantation remains the only curative option for the disease, as most management options focus solely on symptom control. Progress in prenatal diagnosis and fetal therapeutic intervention raises the possibility of in utero treatment. SCD can be diagnosed prenatally in high-risk patients using chorionic villus sampling. Among the possible prenatal treatments, in utero stem cell transplantation (IUSCT) shows the most promise. IUSCT is a non-myeloablative, non-immunosuppressive alternative conferring various unique advantages and may also offer safer postnatal management. Fetal immunologic immaturity could allow engraftment of allogeneic cells before fetal immune system maturation, donor-specific tolerance and lifelong chimerism. In this review, we will discuss SCD, screening and current treatments. We will present the therapeutic rationale for IUSCT, examine the early experimental work and initial human experience, as well as consider primary barriers of clinically implementing IUSCT and the promising approaches to address them.

Use of Wise Device Technology to Measure Adherence to Hydroxyurea Therapy in Youth With Sickle Cell Disease

Despite broad support for hydroxyurea (HU) therapy, suboptimal adherence is reported for youth with sickle cell disease. Valid adherence measurement is crucial to understanding the relationship between medication behavior, disease response, and patient-centered health outcomes. The current pilot study examined the feasibility of the Wise electronic device for longitudinal HU adherence measurement in a sample of 36 youths prescribed HU. The study also explored the association between HU adherence, as measured by the Wise device, with other adherence measures (ie, family report, lab values, pill count, and medication possession ratio). A measure of family-reported acceptability was also completed. Overall, results supported the feasibility of the Wise device (rate of consent=82%, device use=75%, device failure=3%) for HU adherence measurement and most families rated their experience using their device positively (favorable responses ranged from 67% to 100%). Associations between HU adherence, as measured by the Wise device, and other adherence measures were not significant. Overall, the feasibility was supported. The Wise device allows longitudinal measurement of adherence with HU from initiation as a young child (ie, with liquid formulations) through adolescence and provides a novel means of adherence measurement for both clinical and research use.

Hydroxyurea Optimization through Precision Study (HOPS): study protocol for a randomized, multicenter trial in children with sickle cell anemia

Background

Sickle cell disease (SCD) is a severe and devastating hematological disorder that affects over 100,000 persons in the USA and millions worldwide. Hydroxyurea is the primary disease-modifying therapy for the SCD, with proven benefits to reduce both short-term and long-term complications. Despite the well-described inter-patient variability in pharmacokinetics (PK), pharmacodynamics, and optimal dose, hydroxyurea is traditionally initiated at a weight-based dose with a subsequent conservative dose escalation strategy to avoid myelosuppression. Because the dose escalation process is time consuming and requires frequent laboratory checks, many providers default to a fixed dose, resulting in inadequate hydroxyurea exposure and suboptimal benefits for many patients. Results from a single-center trial of individualized, PK-guided dosing of hydroxyurea for children with SCD suggest that individualized dosing achieves the optimal dose more rapidly and provides superior clinical and laboratory benefits than traditional dosing strategies. However, it is not clear whether these results were due to individualized dosing, the young age that hydroxyurea treatment was initiated in the study, or both. The Hydroxyurea Optimization through Precision Study (HOPS) aims to validate the feasibility and benefits of this PK-guided dosing approach in a multi-center trial.

Methods

HOPS is a randomized, multicenter trial comparing standard vs. PK-guided dosing for children with SCD as they initiate hydroxyurea therapy. Participants (ages 6 months through 21 years), recruited from 11 pediatric sickle cell centers across the USA, are randomized to receive hydroxyurea either using a starting dose of 20 mg/kg/day (Standard Arm) or a PK-guided dose (Alternative Arm). PK data will be collected using a novel sparse microsampling approach requiring only 10 μL of blood collected at 3 time-points over 3 h. A protocol-guided strategy more aggressive protocols is then used to guide dose escalations and reductions in both arms following initiation of hydroxyurea. The primary endpoint is the mean %HbF after 6 months of hydroxyurea.

Discussion

HOPS will answer important questions about the clinical feasibility, benefits, and safety of PK-guided dosing of hydroxyurea for children with SCD with potential to change the treatment paradigm from a standard weight-based approach to one that safely and effectively optimize the laboratory and clinical response.

Trial registration

ClinicalTrials.gov NCT03789591. Registered on 28 December 2018.

Changing the Clinical Paradigm of Hydroxyurea Treatment for Sickle Cell Anemia Through Precision Medicine

Sickle cell anemia (SCA) is a common and devastating inherited blood disorder, affecting millions of people across the world. Without treatment, SCA results in tremendous morbidity and early mortality. Hydroxyurea is the primary and most well-established pharmacologic therapy with proven benefits to ameliorate the clinical course of SCA, primarily due to its ability to increase the expression of fetal hemoglobin (HbF), which prevents sickling of red blood cells. The optimal induction of HbF depends upon selection and maintenance of the proper dose that maximizes benefits and minimizes toxicity. Due to the significant interpatient variability in hydroxyurea pharmacokinetics, pharmacodynamics, and dosing, most patients treated with hydroxyurea receive suboptimal doses and have only modest treatment responses. Recognizing this variability, using a precision medicine approach, we developed and prospectively evaluated an individualized dosing model for children with SCA, designed to optimize the hydroxyurea dose and clinical response. We utilize novel laboratory methods and a sparse sampling strategy requiring only 10 μL of blood collected 15 minutes, 60 minutes, and 180 minutes after a test dose. We use Bayesian adaptive control to estimate hydroxyurea exposure and to select an individual, optimal starting dose. This dosing model has resulted in HbF responses >30-40%, levels beyond what is achieved with traditional weight-based dosing and trial and error dose escalation. This hydroxyurea dosing strategy, if widely implemented, has the potential to change the treatment paradigm of hydroxyurea therapy and improve outcomes for the millions of patients with SCA across the world.

Integration of Mobile Health Into Sickle Cell Disease Care to Increase Hydroxyurea Utilization: Protocol for an Efficacy and Implementation Study

BACKGROUND

Hydroxyurea prevents disease complications among patients with sickle cell disease (SCD). Although its efficacy has been endorsed by the National Health Lung and Blood Institute evidence-based guidelines, its adoption is low, both by patients with SCD and providers. Mobile health (mHealth) apps provide benefits in improving medication adherence and self-efficacy among patients with chronic diseases and have facilitated prescription among medical providers. However, mHealth has not been systematically tested as a tool to increase hydroxyurea adherence nor has the combination of mHealth been assessed at both patient and provider levels to increase hydroxyurea utilization.

OBJECTIVE

This study aims to increase hydroxyurea utilization through a combined two-level mHealth intervention for both patients with SCD and their providers with the goals of increasing adherence to hydroxyurea among patients and improve hydroxyurea prescribing behavior among providers.

METHODS

We will test the efficacy of 2 mHealth interventions to increase both patient and provider utilization and knowledge of hydroxyurea in 8 clinical sites of the NHLBI-funded Sickle Cell Disease Implementation Consortium (SCDIC). The patient mHealth intervention, InCharge Health, includes multiple components that address memory, motivation, and knowledge barriers to hydroxyurea use. The provider mHealth intervention, Hydroxyurea Toolbox (HU Toolbox), addresses the clinical knowledge barriers in prescribing and monitoring hydroxyurea. The primary hypothesis is that among adolescents and adults with SCD, adherence to hydroxyurea, as measured by the proportion of days covered (the ratio of the number of days the patient is covered by the medication to the number of days in the treatment period), will increase by at least 20% after 24 weeks of receiving the InCharge Health app, compared with their adherence at baseline. As secondary objectives, we will (1) examine the change in health-related quality of life, acute disease complications, perceived health literacy, and perceived self-efficacy in taking hydroxyurea among patients who use InCharge Health and (2) examine potential increases in the awareness of hydroxyurea benefits and risks, appropriate prescribing, and perceived self-efficacy to correctly administer hydroxyurea therapy among SCD providers between baseline and 9 months of using the HU Toolbox app. We will measure the reach, adoption, implementation, and maintenance of both the InCharge Health and the HU Toolbox apps using the reach, effectiveness, adoption, implementation, and maintenance framework and qualitatively evaluate the implementation of both mHealth interventions.

RESULTS

The study is currently enrolling study participants. Recruitment is anticipated to be completed by mid-2021.

CONCLUSIONS

If this two-level intervention, that is, the combined use of InCharge Health and HU Toolbox apps, demonstrates efficacy in increasing adherence to hydroxyurea and prescribing behavior in patients with SCD and their providers, respectively, both apps will be offered to other institutions outside the SCDIC through a future large-scale implementation-effectiveness study.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04080167; https://clinicaltrials.gov/ct2/show/NCT04080167.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/16319.

Tenofovir disoproxil fumarate induces fetal hemoglobin production in K562 cells and β-YAC transgenic mice: A therapeutic approach for γ-globin induction

Pharmacologic induction of fetal hemoglobin (HbF) is an effective strategy for treating β-hemoglobinopathies like β-thalassemia and sickle cell anemia by ameliorating disease severity. Hydroxyurea is the only FDA-approved agent that induces HbF, but significant nonresponders and toxicity limit its clinical usefulness. This study relates preclinical investigation of Tenofovir disoproxil fumarate (TDF) as a potential HbF inducing agent, using human erythroleukemia cell line and a β-YAC mouse model. Erythroid induction of K562 cells was studied by the benzidine/H₂O₂ reaction, total hemoglobin production was estimated by plasma hemoglobin assay kit, and γ-globin gene expression by RT-qPCR, whereas, fetal hemoglobin production was estimated by flow cytometry and immunofluorescence microscopy. We observed significantly increased γ- globin gene transcription and HbF expression mediated by TDF in K562 cells. Subsequent treatment of β-YAC transgenic mice with TDF confirmed HbF induction in vivo through an increase in γ-globin gene expression and in the percentage of HbF positive red blood cells. Moreover, TDF showed no cytotoxic effect at HbF inducing concentrations. These data support the potential development of TDF for the treatment of hematological disorders, including β-thalassemia and sickle cell anemia.

Association Between Vaso-Occlusive Crises and Opioid Prescriptions Among Patients with Sickle Cell Disease: A Retrospective Claims-Based Study

Background/Objectives: Among sickle cell disease (SCD) patients, vaso-occlusive crises (VOCs) are recurrent and unpredictable attacks of acute pain. These pain crises are often treated with analgesics, including opioids, which have been associated with misuse and overdose. The aim of this study was to examine the association between VOC events and opioid use and assess the association between opioid prescriptions and health care resource utilization among SCD patients. Methods: This was a retrospective cohort study using Texas Medicaid medical and prescription claims between September 2011 and August 2016. The index date was the first SCD diagnosis. Patients (2-63 years) with at least one inpatient or two outpatient SCD diagnoses, who were continuously enrolled during 12 months postindex, were included in the study. The primary outcome was number of opioid prescriptions, while the independent variable was number of VOC events. Covariates included age, gender, nonopioid medication use, nonstudy SCD-related medication (penicillin and folic acid) use, evidence of blood transfusions, number of SCD-related complications, number of SCD-related comorbid conditions, and Charlson Comorbidity Index score. Negative binomial regression analysis was used to address study objectives. Results: Of 3368 included patients, 1978 (58.7%) had at least one opioid prescription with a mean of 4.2 (SD=7.2). Overall, 2071 (61.5%) had at least one VOC event with an average of 2.9 (SD=4.4). The results from the negative binomial regression showed that for every increase in VOC events, the number of opioid prescriptions increased by 9.5% (Incidence rate ratio=1.095, 95% CI: 1.078-1.111; P ≤ 0.0001). Other significant covariates associated with higher opioid use included age (13 and older compared to 2-12) and increase in the number of nonopioid pain medications, nonstudy SCD-related medications, and SCD-related complications. Conclusions: The majority of SCD patients had at least one VOC event and were prescribed opioids during the 12-month study period. We found that each VOC event was associated with a 9.5% increase in the use of opioids. SCD guidelines recommend opioids for the treatment of VOC-related pain. Payers and providers should be aware of opioid use in this population, consider appropriate VOC prevention measures, and provide SCD patients with access to appropriate pain management.

Association between Vaso-occlusive Crises and Opioid Prescriptions among Patients with Sickle Cell Disease: A Retrospective Claims-based Study

BACKGROUND/OBJECTIVES

Among sickle cell disease (SCD) patients, vaso-occlusive crises (VOCs) are recurrent and unpredictable attacks of acute pain. These pain crises are often treated with analgesics, including opioids, which have been associated with misuse and overdose. The aim of this study was to examine the association between VOC events and opioid use and assess the association between opioid prescriptions and health care resource utilization among SCD patients.

METHODS

This was a retrospective cohort study using Texas Medicaid medical and prescription claims between September 2011 and August 2016. The index date was the first SCD diagnosis. Patients (2-63 years) with at least one inpatient or two outpatient SCD diagnoses, who were continuously enrolled during 12 months postindex, were included in the study. The primary outcome was number of opioid prescriptions, while the independent variable was number of VOC events. Covariates included age, gender, nonopioid medication use, nonstudy SCD-related medication (penicillin and folic acid) use, evidence of blood transfusions, number of SCD-related complications, number of SCD-related comorbid conditions, and Charlson Comorbidity Index score. Negative binomial regression analysis was used to address study objectives.

RESULTS

Of 3368 included patients, 1978 (58.7%) had at least one opioid prescription with a mean of 4.2 (SD=7.2). Overall, 2071 (61.5%) had at least one VOC event with an average of 2.9 (SD=4.4). The results from the negative binomial regression showed that for every increase in VOC events, the number of opioid prescriptions increased by 9.5% (Incidence rate ratio=1.095, 95% CI: 1.078-1.111; P ≤ 0.0001). Other significant covariates associated with higher opioid use included age (13 and older compared to 2-12) and increase in the number of nonopioid pain medications, nonstudy SCD-related medications, and SCD-related complications.

CONCLUSIONS

The majority of SCD patients had at least one VOC event and were prescribed opioids during the 12-month study period. We found that each VOC event was associated with a 9.5% increase in the use of opioids. SCD guidelines recommend opioids for the treatment of VOC-related pain. Payers and providers should be aware of opioid use in this population, consider appropriate VOC prevention measures, and provide SCD patients with access to appropriate pain management.

The vaso-occlusive pain crisis in sickle cell disease: Definition, pathophysiology, and management

Early diagnosis, treatment, and prevention of a vaso-occlusive crisis (VOC) are critical to the management of patients with sickle cell disease. It is essential to differentiate between VOC-associated pain and chronic pain, hyperalgesia, neuropathy, and neuropathic pain. The pathophysiology of VOCs includes polymerization of abnormal sickle hemoglobin, inflammation, and adhesion. Hydroxyurea, L-glutamine, crizanlizumab, and voxelotor have been approved by the US Food and Drug Administration for reducing the frequency of VOCs; the European Medicines Agency has approved only hydroxyurea. Other novel treatments are in late-stage clinical development in both the United States and the European Union. The development of agents for prevention and treatment of VOCs should be driven by our understanding of its pathophysiology.

A Systematic Review of Medication Adherence Interventions in Pediatric Sickle Cell Disease

Objective

Adherence to medication regimens is of critical importance in sickle cell disease (SCD). Most notably, data indicate that hydroxyurea, penicillin, and iron chelators increase life expectancy and decrease comorbid medical problems (e.g., strokes). However, average pediatric SCD adherence rates are only 55–74%. Studies have introduced interventions for pediatric SCD adherence, but no review has synthesized these data.

Methods

We conducted a systematic review of interventions for enhancing medication adherence in pediatric SCD. There were 9 studies that met inclusion and exclusion criteria. The Pediatric Self-Management Model provided a framework for organizing the modifiable factors targeted by existing interventions.

Results

The 9 studies had high risk of bias levels and most targeted hydroxyurea. All studies used multiple measures of adherence, the interventions were multicomponent, and most included behavioral or technological interventions. There was variability in terms of whether the intervention targeted the individual, family, community, or healthcare system.

Conclusions

Consistent with the broader adherence literature, targeting knowledge alone was insufficient in increasing adherence. Findings suggest that reminders and targeting self-efficacy were key to success. In addition, addressing multiple domains in an intervention yielded larger effects on adherence. Although these results are promising, this review highlights several limitations of the extant literature, including a paucity of intervention studies and several methodological weaknesses, such as small sample sizes, few randomized controlled trials, and variable measures of adherence. Recommendations for advancing scientific understanding of adherence promoting interventions in pediatric SCD are provided.

Association between hydroxycarbamide exposure and neurocognitive function in adolescents with sickle cell disease

Patients with sickle cell disease (SCD) are at increased risk for neurocognitive impairments. While disease-modifying treatment, such as hydroxycarbamide (hydroxyurea), may decrease this risk, it has not been systematically investigated in children with SCD. We screened neurocognitive functioning in 103 adolescents with SCD (16-17 years, 50% female) and compared outcomes between patients with a history of exposure to hydroxycarbamide (n = 12 HbSC/HbSβ⁺ thalassaemia; n = 52 HbSS/HbSβ⁰ thalassaemia) and those never treated with hydroxycarbamide (n = 31 HbSC/HbSβ⁺ thalassaemia; n = 8 HbSS/HbSβ⁰ thalassaemia). Demographic distributions were similar between the groups. After adjusting for socioeconomic status, the hydroxycarbamide group had significantly higher scores on nonverbal IQ (HbSC/HbSβ thalassaemia: P = 0·036, effect size [d] = 0·65), reaction speed (HbSS/HbSβ⁰ thalassaemia: P = 0·002, d = 1·70), sustained attention (HbSS/HbSβ⁰ thalassaemia: P = 0·014, d = 1·30), working memory (HbSC/HbSβ⁺ thalassaemia: P = 0·034, d = 0·71) and verbal memory (HbSC/HbSβ⁺ thalassaemia: P = 0·038, d = 0·84) when compared to those who did not receive hydroxycarbamide. In patients with HbSS/HbSβ⁰ thalassaemia, longer treatment duration with hydroxycarbamide was associated with better verbal memory (P = 0·009) and reading (P = 0·002). Markers of hydroxycarbamide effect, including higher fetal haemoglobin (HbF), higher mean corpuscular volume (MCV) and lower white blood cell count (WBC), were associated with better verbal fluency (HbF: P = 0·014, MCV: P = 0·006, WBC: P = 0·047) and reading (MCV: P = 0·021, WBC: P = 0·037). Cognitive impairment may be mitigated by exposure to hydroxycarbamide in adolescents with SCD.

The role of hydroxyurea in decreasing the occurrence of vasso-occulusive crisis in pediatric patients with sickle cell disease at King Saud Medical City in Riyadh, Saudi Arabia

OBJECTIVES

To measure the incidence of vaso-occlusive crises (VOC) and the role of hydroxyurea (HU) in reducing VOC in sickle cell anemia  patients being treated at a large tertiary care setting in Kingdom of Saudi Arabia (KSA). The secondary objective of this study is to observe the gradual improvement in laboratory data (white blood cell [WBC], platelets, mean corpuscular volume [MCV], hemoglobin [Hgb], HgbF) following regular use of HU. Methods: Clinical effectiveness of HU was evaluated in a large pediatric population using a retrospective cohort, non-interventional, pre-post treatment study designed to control disease severity selection bias. The cohort included children with SCA (sickle cell (SS), sickle-beta thalassemia) at King Saud Medical City, Riyadh, KSA, who initiated HU between January 2012 and June 2017. For each patient healthcare utilization, laboratory values, and clinical outcomes were observed for an equal duration of time pre and post hydroxyurea. Results: Out of 416 SCD patients, 128 children with SCD who initiated HU, of them 82 met the eligibility criteria. After initiation of HU, there was significant reduction in both VOC (80%) and length of stay (LOS) (73%). Significant increase in Hgb (13%), MCV (10%), and HgbF (28%) and significant decrease in WBC (28%) was observed. Only the mean platelet count decreased by 3% with a p greater than 0.05. Conclusion: Hydroxyurea treatment significantly decreased episodes of VOC and LOS, it also led to reductions in hospitalizations and significant improvement in complete blood count indices.

Barriers to the use of hydroxyurea in the management of sickle cell disease in Nigeria

Hydroxyurea (HU) is a well-known Hb F-inducing agent with proven clinical and laboratory efficacy for patients with sickle cell disease. However, concerns about its long-term safety and toxicity have limited its prescription by physicians and acceptability by patients. Thus, this study aims to evaluate clinician's barriers to the use of HU in the management of patients with sickle cell disease in Nigeria. An online survey targeted physicians in pediatrics, hematology, medicine, family medicine and general medical practice managing sickle cell disease in Nigeria. The survey was in four sections: demographic, knowledge and experience with HU, and barriers to the use of HU. Ninety-one (73.0%) of 123 contacts completed the survey. Seventy-three percent and 74.0% of the respondents noted that HU reduced transfusion rates and improved overall quality of life (QOL) of patients, respectively. While the majority of the practitioners (55.6%) see between 10-50 patients per month, most (66.7%) write <5 prescriptions for HU per month. Lack of a national guideline for use of HU, especially in children (52.0%), concern for infertility (52.0%), and safety profile of HU in pregnancy and lactation (48.2%), top the factors considered by the respondents as major barriers to the use of HU. Hydroxyurea is grossly under prescribed in Nigeria, despite that the vast majority of physicians who attend patients with sickle cell disease know about its clinical efficacy. Evidence-based clinical practice guidelines could be explored as a way to standardize practices and improve confidence of practitioners to improve physicians' prescription of HU in the management of sickle cell disease.

Genomic variants in members of the Krüppel-like factor gene family are associated with disease severity and hydroxyurea treatment efficacy in β-hemoglobinopathies patients

Aim: β-Type hemoglobinopathies are characterized by vast phenotypic diversity as far as disease severity is concerned, while differences have also been observed in hydroxyurea (HU) treatment efficacy. These differences are partly attributed to the residual expression of fetal hemoglobin (HbF) in adulthood. The Krüppel-like family of transcription factors (KLFs) are a set of zinc finger DNA-binding proteins which play a major role in HbF regulation. Here, we explored the possible association of variants in KLF gene family members with response to HU treatment efficacy and disease severity in β-hemoglobinopathies patients. Materials & methods: Six tag single nucleotide polymorphisms, located in four KLF genes, namely KLF3, KLF4, KLF9 and KLF10, were analyzed in 110 β-thalassemia major patients (TDT), 18 nontransfusion dependent β-thalassemia patients (NTDT), 82 sickle cell disease/β-thalassemia compound heterozygous patients and 85 healthy individuals as controls. Results: Our findings show that a KLF4 genomic variant (rs2236599) is associated with HU treatment efficacy in sickle cell disease/β-thalassemia compound heterozygous patients and two KLF10 genomic variants (rs980112, rs3191333) are associated with persistent HbF levels in NTDT patients. Conclusion: Our findings provide evidence that genomic variants located in KLF10 gene may be considered as potential prognostic biomarkers of β-thalassemia clinical severity and an additional variant in KLF4 gene as a pharmacogenomic biomarker, predicting response to HU treatment.

Hydroxyurea: Pattern of Use, Patient Adherence, and Safety Profile in Patients with Sickle Cell Disease in Oman

OBJECTIVES

Many barriers contribute to the underutilization of hydroxyurea (HU) in the treatment of sickle cell disease (SCD), and adherence to its use is often reported to be suboptimal. It is important to have information on the safety of HU in patients with SCD. Our study assessed the pattern of use, patients' adherence to medication, discontinuation of use, and safety of HU in patients with SCD.

METHODS

This cross-sectional study was conducted in the department of medicine of a referral hospital in Oman over five months and included a review of patient files and patient interview. Approval was obtained from the Regional Research and Ethics Committee of the A'Dakhiliyah Governorate and the hospital administration. The parameters were compared between groups using the chi-square test.

RESULTS

Of 298 patients studied, 128 (43.0%) had used HU at some points. The difference in the prevalence of HU use was statistically significant based only on age (p = 0.014), with younger patients more likely to be currently using HU or used HU in the past. The majority of patients were adherent (82.5%) based on self-reported adherence. The prevalence of discontinuation (temporary or permanent) of HU use was high (57.0%), and suspected adverse drug reaction (ADR) was the most common reason. Among those who had never used HU, 33.7% of patients had an indication for the initiation of HU. A quarter of patients who used HU developed a suspected ADR, with blood abnormalities being the commonest. The duration of HU use influenced ADR prevalence (p = 0.015).

CONCLUSIONS

Among the current users of HU, the majority of the patients were adherent based on self-reported medication adherence. The prevalence of discontinuation of HU use and instances of non-initiation of HU among those indicated were high. A larger study, ideally of a prospective nature, in various governorates of Oman, would provide a wider picture at the national level.

Relationship of Omega-3 fatty acids DHA and EPA with the inflammatory biomarker hs-CRP in children with sickle cell anemia

BACKGROUND

Inflammation and vaso-occlusion play key roles in Sickle Cell Disease (SCD) pathophysiology. Lipoxygenase products of the omega-3 fatty acids (O3FAs), docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids, are potent anti-inflammatory mediators modulating pain. O3FAs decrease episodes of vaso-occlusion in SCD.

METHODS

We assessed erythrocyte fatty acid composition in two major cell membrane phospholipids, phosphatidylcholine and phosphatidylethanolamine, in children with SCD HbSS-disease (n = 38) and age/race-matched HbAA-controls (n = 18). Ratio of pro-inflammatory arachidonic acid (AA) to anti-inflammatory DHA and EPA (FA-Ratio), and its relationship to hs-CRP were evaluated.

RESULTS

FA-Ratios were increased in both phosphatidylcholine and phosphatidylethanolamine in HbSS compared to controls. Correlations were noted in HbSS subjects between hs-CRP and FA-Ratios (p = 0.011). FA-Ratios increased with age (p = 0.0007) due to an increase in pro-inflammatory AA with a concomitant decrease in anti-inflammatory DHA.

CONCLUSIONS

Findings demonstrate relative deficiencies in HbSS of the anti-inflammatory precursor fatty acids DHA and EPA, which correlates positively with hs-CRP.

Thiourea derivatives induce fetal hemoglobin production in-vitro: A new class of potential therapeutic agents for β-thalassemia

Fetal hemoglobin (HbF) induction is a cost-effective therapeutic approach for the treatment of β-hemoglobinopathies like β-thalassemia and sickle cell anemia. The present study discusses the potential of thiourea derivatives as new class of compounds that induce the fetal hemoglobin production. HbF inducing effect of thiourea derivatives was studied using experimental cell system, the human erythroleukemic K562 cell line. Erythroid induction of K562 cells was studied by the benzidine/H₂O₂ reaction, total hemoglobin production was estimated by plasma hemoglobin assay kit, and γ-globin gene expression by RT-qPCR, whereas fetal hemoglobin production was estimated by flow cytometry and immunofluorescence microscopy. The results indicated that newly synthesized thiourea derivative are potent inducers of erythroid differentiation of K562 cells with an increased γ-globin gene expression and fetal hemoglobin production. Moreover, these compounds showed no cytotoxic effect and inhibition on K562 cells at HbF inducing concentrations. It is important to note that hydroxyurea is a cytotoxic chemotherapeutic agent and have deleterious side effects, reflecting the need to identify new safe and effective HbF induces. These results signify thiourea derivatives as promising HbF inducers, with the potential to be studied against hematological disorders, including β-thalassemia and sickle cell anemia.

Sickle Cell Disease: Monitoring, Current Treatment, and Therapeutics Under Development

Screening and early detection of organ injury, as well as expanded use of red cell transfusion and hydroxyurea in children have changed best practices for clinical care in sickle cell disease. The current standard of care for children with sickle cell disease is discussed through a review of screening recommendations, disease monitoring, and approach to treatment. Novel pharmacologic agents under investigation in clinical trials are also reviewed.

Objectively measured physical activity levels and sedentary time in children and adolescents with sickle cell anemia

The aim of this study was to identify the levels of physical activity and sedentary behaviour of children and adolescents with sickle cell disease (SCA) compared to healthy individuals. A cross-sectional study with a quantitative approach was performed at a reference center for the treatment of patients with hemoglobinopathies in northeastern Brazil. Patients were recruited between October 2015 and January 2017. Eligible participants answered a Physical Activity Questionnaire for Older Children and Adolescents (PAQ-C) and were instructed to use an ActiGraph wGT3X-BT triaxial accelerometer for seven consecutive days. Fifty patients (and their 50 controls matched for age and sex) were then evaluated. We observed lower moderate (19.2 ± 11.9 and 27.1 ± 13.8 min/d; p<0.01) and vigorous PA (3.6 ± 4.1 and 7.8 ± 7.4 min/d; p<0.01) in cases than controls, respectively. There was also a significant difference among cases and controls in the following variables: total of steps (51010 ± 19600 and 59105 ± 22650; p = 0.04) and "total caloric expenditure" (1015 ± 516 and 2404 ± 1308; p<0.01), with the lowest values for the patients with SCA for all variables. Children and adolescents with SCA presented lower levels of physical activity than healthy children and adolescents, either when evaluated by PAQs or by accelerometer.

Improving routine outpatient monitoring for patients with sickle-cell disease on hydroxyurea

Hydroxyurea is the gold standard treatment for prevention of vaso-occlusive crises in patients with sickle-cell anaemia. It has a narrow therapeutic index and dangerous side effects including cytopenias. There is high variation in dose–response across the population. Therefore, a robust outpatient monitoring programme is crucial to ensure efficacy and safety of treatment. However, there has historically been difficulty engaging the target population in regular laboratory test monitoring programmes. This project aimed to ensure that all patients on hydroxyurea had routine blood tests at least once every 2 months which were reviewed and acted upon within the 3-year project life cycle. A specialist haematology nurse prescriber clinic service was introduced, first informally, and then formally to take blood tests, alter medication dosing, prescribe it and then write a clinic letter. The mean number of tests per patient per year rose from 0.21 at baseline to 9.05 after 2 years of the formal nurse prescriber clinic. This led to an associated increase in dose changes from 0.23 to 1.45 per patient per year. This improved the number of patients on the optimum dose of hydroxyurea. Furthermore, due to increased confidence in the outpatient monitoring, the total number of people being prescribed hydroxyurea increased from 26 to 42. Restriction of prescriptions to only those enrolled in the service has prevented unmonitored patients being at risk of the potential toxicities associated with doses that are too high. The introduction of a formal nurse-led clinic has improved the safety, efficacy and compliance and increased the number of patients on the gold standard preventative treatment for vaso-occlusive crises in sickle-cell anaemia.

Hydroxyurea prescription, availability and use for children with sickle cell disease in Italy: Results of a National Multicenter survey

BACKGROUND

The number of patients with sickle cell disease (SCD) has increased in Italy in the past decade due to immigration. In spite of the established efficacy of hydroxyurea (HU) in childhood, population-based data regarding its prescription and effectiveness come mainly from studies performed in adults or outside Europe.

POPULATION AND METHODS

The Hydroxyurea in SCD: A Large Nation-wide Cohort Study from Italy was a retrospective cohort study of adult and pediatric patients with SCD attending 32 centers. Pediatric data are analyzed separately.

RESULTS

Out of 504 children followed in 11 centers, 206 (40%) were on HU (194 SS/Sβ°, 12 SC/Sß+); 74% came from Sub-Saharian Africa and 18% from Europe. HU therapy indications for SS/Sβ° patients were as follows: 57% painful vaso-occlusive crisis, acute chest syndrome or both, 24% anemia, 8% anemia, and other reasons (the majority had Hb ≤ 8-8.5 g/dl, revealing scarce acceptance of low Hb values by pediatric hematologist). Mean starting dose was 15.5 mg/kg, and dose at full regimen was 17.1 mg/kg. Mean age at HU therapy was 7.68 years, although it was lower for SS/Sβ° patients. Only 10% started HU before 3 years. In 92%, 500 mg capsule was used; in 6%, the galenic was used; and in 2%, 100 mg tablet was used. Significant reduction of clinical events and inpatients admissions, with improvement in hematological parameters, was observed for SS/Sβ° patients and a trend toward improvement for SC/Sß+ patients was also observed.

CONCLUSIONS

HU effectiveness is demonstrated in a national cohort of children with SCD living in Italy, even at a lower dose than recommended, revealing good adherence to a treatment program by a socially vulnerable group of patients such as immigrants.

Hydroxyurea therapy in UK children with sickle cell anaemia: A single-centre experience

INTRODUCTION

Despite the demonstrated efficacy of hydroxyurea therapy, children with sickle cell anaemia in the UK are preferentially managed with supportive care or transfusion. Hydroxyurea is reserved for children with severe disease phenotype. This is in contrast to North America and other countries where hydroxyurea is widely used for children of all clinical phenotypes. The conservative UK practice may in part be due to concerns about toxicity, in particular marrow suppression with high doses, and growth in children.

METHODS AND RESULTS

We monitored 37 paediatric patients with sickle cell anaemia who were treated with hydroxyurea at a single UK treatment centre. Therapy was well tolerated and mild transient cytopenias were the only toxicity observed. Comparative analysis of patients receiving ≥26 mg/kg/day versus <26 mg/kg/day demonstrates increasing dose has a significant positive effect on foetal haemoglobin (Hb; 29.2% vs. 20.4%, P = 0.0151), mean cell volume (94.4 vs. 86.5, P = 0.0183) and reticulocyte count (99.66 × 10⁹ /l vs. 164.3 × 10⁹ /l, P = 0.0059). Marrow suppression was not a clinical problem with high-dose treatment, Hb 92.25 g/l versus 91.81 g/l (ns), neutrophil count 3.3 × 10⁹ /l versus 4.8 × 10⁹ /l (ns) and platelet count 232.4 × 10⁹ /l versus 302.2 × 10⁹ /l (ns). Normal growth rates were maintained in all children. Good adherence to therapy was a significant factor in reducing hospitalisations.

CONCLUSION

This study demonstrates the effectiveness and safety in practice of high-dose hydroxyurea as a disease-modifying therapy, which we advocate for all children with sickle cell anaemia.

Randomized feasibility trial to improve hydroxyurea adherence in youth ages 10-18 years through community health workers: The HABIT study

INTRODUCTION

The main therapeutic intervention for sickle cell disease (SCD) is hydroxyurea (HU). The effect of HU is largely through dose-dependent induction of fetal hemoglobin (HbF). Poor HU adherence is common among adolescents.

METHODS

Our 6-month, two-site pilot intervention trial, "HABIT," was led by culturally aligned community health workers (CHWs). CHWs performed support primarily through home visits, augmented by tailored text message reminders. Dyads of youth with SCD ages 10-18 years and a parent were enrolled. A customized HbF biomarker, the percentage decrease from each patients' highest historical HU-induced HbF, "Personal best," was used to qualify for enrollment and assess HU adherence. Two primary outcomes were as follows: (1) intervention feasibility and acceptability and (2) HU adherence measured in three ways: monthly percentage improvement toward HbF Personal best, proportion of days covered (PDC) by HU, and self-report.

RESULTS

Twenty-eight dyads were enrolled, of which 89% were retained. Feasibility and acceptability were excellent. Controlling for group assignment and month of intervention, the intervention group improved percentage decrease from Personal best by 2.3% per month during months 0-4 (P = 0.30), with similar improvement in adherence demonstrated using pharmacy records. Self-reported adherence did not correlate. Dyads viewed CHWs as supportive for learning about SCD and HU, living with SCD and making progress in coordinated self-management responsibility to support a daily HU habit. Most parents and youth appreciated text message HU reminders.

CONCLUSIONS

The HABIT pilot intervention demonstrated feasibility and acceptability with promising effect toward improved medication adherence. Testing in a larger multisite intervention trial is warranted.