Browsing by Subject "Sickle cell anemia"
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Item Acute kidney injury in hospitalized children with sickle cell anemia(BMC, 2022-03-18) Batte, Anthony; Menon, Sahit; Ssenkusu, John; Kiguli, Sarah; Kalyesubula, Robert; Lubega, Joseph; Mutebi, Edrisa Ibrahim; Opoka, Robert O.; John, Chandy C.; Starr, Michelle C.; Conroy, Andrea L.; Pediatrics, School of MedicineBackground: Children with sickle cell anemia (SCA) are at increased risk of acute kidney injury (AKI) that may lead to death or chronic kidney disease. This study evaluated AKI prevalence and risk factors in children with SCA hospitalized with a vaso-occlusive crisis (VOC) in a low-resource setting. Further, we evaluated whether modifications to the Kidney Disease: Improving Global Outcomes (KDIGO) definition would influence clinical outcomes of AKI in children with SCA hospitalized with a VOC. Methods: We prospectively enrolled 185 children from 2 - 18 years of age with SCA (Hemoglobin SS) hospitalized with a VOC at a tertiary hospital in Uganda. Kidney function was assessed on admission, 24-48 h of hospitalization, and day 7 or discharge. Creatinine was measured enzymatically using an isotype-dilution mass spectrometry traceable method. AKI was defined using the original-KDIGO definition as ≥ 1.5-fold change in creatinine within seven days or an absolute change of ≥ 0.3 mg/dl within 48 h. The SCA modified-KDIGO (sKDIGO) definition excluded children with a 1.5-fold change in creatinine from 0.2 mg/dL to 0.3 mg/dL. Results: Using KDIGO, 90/185 (48.7%) children had AKI with 61/185 (33.0%) AKI cases present on admission, and 29/124 (23.4%) cases of incident AKI. Overall, 23 children with AKI had a 1.5-fold increase in creatinine from 0.2 mg/dL to 0.3 m/dL. Using the sKDIGO-definition, 67/185 (36.2%) children had AKI with 43/185 (23.2%) cases on admission, and 24/142 (16.9%) cases of incident AKI. The sKDIGO definition, but not the original-KDIGO definition, was associated with increased mortality (0.9% vs. 7.5%, p = 0.024). Using logistic regression, AKI risk factors included age (aOR, 1.10, 95% CI 1.10, 1.20), hypovolemia (aOR, 2.98, 95% CI 1.08, 8.23), tender hepatomegaly (aOR, 2.46, 95% CI 1.05, 5.81), and infection (aOR, 2.63, 95% CI 1.19, 5.81) (p < 0.05). Conclusion: These results demonstrate that AKI is a common complication in children with SCA admitted with VOC. The sKDIGO definition of AKI in children with SCA was a better predictor of clinical outcomes in children. There is need for promotion of targeted interventions to ensure early identification and treatment of AKI in children with SCA.Item Cost-Effectiveness of Hydroxyurea for Sickle Cell Anemia in a Low-Income African Setting: A Model-Based Evaluation of Two Dosing Regimens(Springer, 2023) Teigen, David; Opoka, Robert O.; Kasirye, Phillip; Nabaggala, Catherine; Hume, Heather A.; Blomberg, Bjørn; John, Chandy C.; Ware, Russell E.; Robberstad, Bjarne; Pediatrics, School of MedicineBackground and objective: The disease burden of sickle cell anemia (SCA) in sub-Saharan African (SSA) countries is substantial, with many children dying without an established diagnosis or proper treatment. The global burden of SCA is increasing each year, making therapeutic intervention a high priority. Hydroxyurea is the only disease-modifying therapy with proven feasibility and efficacy suitable for SSA; however, no one has quantified the health economic implications of its use. Therefore, from the perspective of the health care provider, we estimated the incremental cost-effectiveness of hydroxyurea as a fixed-dose regimen or maximum tolerated dose (MTD) regimen, versus SCA care without hydroxyurea. Methods: We estimated the cost of providing outpatient treatment at a pediatric sickle cell clinic in Kampala, Uganda. These estimates were used in a discrete-event simulation model to project mean costs (2021 US$), disability-adjusted life years (DALYs), and consumption of blood products per patient (450 mL units), for patients between 9 months and 18 years of age. We calculated cost-effectiveness as the ratio of incremental costs over incremental DALYs averted, discounted at 3% annually. To test the robustness of our findings, and the impact of uncertainty, we conducted probabilistic and one-way sensitivity analyses, scenario analysis, and price threshold analyses. Results: Hydroxyurea treatment averted an expected 1.37 DALYs and saved US$ 191 per patient if administered at the MTD, compared with SCA care without hydroxyurea. In comparison, hydroxyurea at a fixed dose averted 0.80 DALYs per patient at an incremental cost of US$ 2. The MTD strategy saved 11.2 (95% CI 11.1-11.4) units of blood per patient, compared with 9.1 (95% CI 9.0-9.2) units of blood per patient at the fixed-dose alternative. Conclusions: Hydroxyurea at MTD is likely to improve quality of life and reduce the consumption of blood products for children with SCA living in Uganda. Compared with a fixed dose regimen, treatment dosing at MTD is likely to be a cost-effective treatment for SCA, using realistic ranges of hydroxyurea costs that are relevant across SSA. Compared with no use of the drug, hydroxyurea could lead to substantial net savings per patient, while reducing the disease morbidity and mortality and increasing quality of life.Item Exercise Induced Changes of Vital Signs in Adults with Sickle Cell Disease(Wiley, 2021) Johnson, Solomon; Gordeuk, Victor R.; Machado, Roberto; Gibbs, J. Simon R.; Hildesheim, Mariana; Little, Jane A.; Kato, Gregory J.; Gladwin, Mark T.; Nouraie, Mehdi; Medicine, School of MedicineThe six-minute walk test (6MWT) has been used in patients with sickle cell disease (SCD), in conjunction with tricuspid regurgitant velocity (TRV) and plasma N-terminal pro-brain natriuretic peptide (NT-pro BNP), to assess risk of having pulmonary hypertension. Exercise-induced vital sign changes (VSCs) are predictors of clinical outcomes in other diseases. In this study, we assess the predictors and prognostic value of 6MWT VSC in adult SCD patients. Data from a multinational study of SCD patients (Treatment of Pulmonary Hypertension with Sildenafil: walk-PHaSST) were used to calculate the 6MWT VSC. Predictors of VSC were identified by a multivariable analysis, and a survival analysis was conducted by the Cox proportional hazard method. An increase in heart rate was observed in 90% of the 630 SCD adults, 77% of patients had an increase in systolic blood pressure (SBP), and 50% of patients had a decrease in oxygen saturation. TRV (odds ratio [OR] = 1.82, p = .020), absolute reticulocyte count (OR = 1.03, p < .001), and hemoglobin (OR = 0.99, p = .035) predicted oxygen desaturation ≥ 3% during the 6MWT. In the adjusted analysis, SBP increase during the 6MWT was associated with improved survival (hazards ratio = 0.3, 95% confidence interval: 0.1-0.8). Increases in heart rate and blood pressure, as well as oxygen desaturation, are common in adults with SCD during the 6MWT. VSC is associated with markers of anemia and TRV and can be used for risk stratification. Any increase in SBP during the 6MWT was associated with improved survival and may be indicative of a patient's ability to increase stroke volume.Item Hydroxyurea reduces infections in children with sickle cell anemia in Uganda(American Society of Hematology, 2024) Namazzi, Ruth; Bond, Caitlin; Conroy, Andrea L.; Datta, Dibyadyuti; Tagoola, Abner; Goings, Michael J.; Jang, Jeong Hoon; Ware, Russell E.; Opoka, Robert; John, Chandy C.; Pediatrics, School of MedicineAfter starting hydroxyurea treatment, Ugandan children with sickle cell anemia had 60% fewer severe or invasive infections, including malaria, bacteremia, respiratory tract infections, and gastroenteritis, than before starting hydroxyurea treatment (incidence rate ratio, 0.40 [ 95% confidence interval, 0.29-0.54 ]; P < .001 ).Item IL-18 mediates sickle cell cardiomyopathy and ventricular arrhythmias(American Society of Hematology, 2021) Gupta, Akash; Fei, Yu-Dong; Kim, Tae Yun; Xie, An; Batai, Ken; Greener, Ian; Tang, Haiyang; Ciftci-Yilmaz, Sultan; Juneman, Elizabeth; Indik, Julia H.; Shi, Guanbin; Christensen, Jared; Gupta, Geetanjali; Hillery, Cheryl; Kansal, Mayank M.; Parikh, Devang S.; Zhou, Tong; Yuan, Jason X-J; Kanthi, Yogendra; Bronk, Peter; Koren, Gideon; Kittles, Rick; Duarte, Julio D.; Garcia, Joe G. N.; Machado, Roberto F.; Dudley, Samuel C.; Choi, Bum-Rak; Desai, Ankit A.; Medicine, School of MedicinePrevious reports indicate that IL18 is a novel candidate gene for diastolic dysfunction in sickle cell disease (SCD)-related cardiomyopathy. We hypothesize that interleukin-18 (IL-18) mediates the development of cardiomyopathy and ventricular tachycardia (VT) in SCD. Compared with control mice, a humanized mouse model of SCD exhibited increased cardiac fibrosis, prolonged duration of action potential, higher VT inducibility in vivo, higher cardiac NF-κB phosphorylation, and higher circulating IL-18 levels, as well as reduced voltage-gated potassium channel expression, which translates to reduced transient outward potassium current (Ito) in isolated cardiomyocytes. Administering IL-18 to isolated mouse hearts resulted in VT originating from the right ventricle and further reduced Ito in SCD mouse cardiomyocytes. Sustained IL-18 inhibition via IL-18-binding protein resulted in decreased cardiac fibrosis and NF-κB phosphorylation, improved diastolic function, normalized electrical remodeling, and attenuated IL-18-mediated VT in SCD mice. Patients with SCD and either myocardial fibrosis or increased QTc displayed greater IL18 gene expression in peripheral blood mononuclear cells (PBMCs), and QTc was strongly correlated with plasma IL-18 levels. PBMC-derived IL18 gene expression was increased in patients who did not survive compared with those who did. IL-18 is a mediator of sickle cell cardiomyopathy and VT in mice and a novel therapeutic target in patients at risk for sudden death.Item Neutrophil gelatinase-associated lipocalin is elevated in children with acute kidney injury and sickle cell anemia, and predicts mortality(Elsevier, 2022) Batte, Anthony; Menon, Sahit; Ssenkusu, John M.; Kiguli, Sarah; Kalyesubula, Robert; Lubega, Joseph; Berrens, Zachary; Mutebi, Edrisa Ibrahim; Ogwang, Rodney; Opoka, Robert O.; John, Chandy C.; Conroy, Andrea L.; Pediatrics, School of MedicineUrine neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of acute kidney injury that has been adapted to a urine dipstick test. However, there is limited data on its use in low- and-middle-income countries where diagnosis of acute kidney injury remains a challenge. To study this, we prospectively enrolled 250 children with sickle cell anemia aged two to 18 years encompassing 185 children hospitalized with a vaso-occlusive pain crisis and a reference group of 65 children attending the sickle cell clinic for routine care follow up. Kidney injury was defined using serial creatinine measures and a modified-Kidney Disease Improving Global Outcome definition for sickle cell anemia. Urine NGAL was measured using the NGAL dipstick and a laboratory reference. The mean age of children enrolled was 8.9 years and 42.8% were female. Among hospitalized children, 36.2% had kidney injury and 3.2% died. Measured urine NGAL levels by the dipstick were strongly correlated with the standard enzyme-linked immunosorbent assay for urine NGAL (hospitalized children, 0.71; routine care reference, 0.88). NGAL levels were elevated in kidney injury and significantly increased across injury stages. Hospitalized children with a high-risk dipstick test (300ng/mL and more) had a 2.47-fold relative risk of kidney injury (95% confidence interval 1.68 to 3.61) and 7.28 increased risk of death (95% confidence interval 1.10 to 26.81) adjusting for age and sex. Thus, urine NGAL levels were found to be significantly elevated in children with sickle cell anemia and acute kidney injury and may predict mortality.Item Obstacles and Circumvention Strategies for Hematopoietic Stem Cell Transduction by Recombinant Adeno-associated Virus Vectors(2009-03-18T18:55:15Z) Maina, Caroline Njeri; Srivastava, Arun; Clapp, D. Wade; Yoder, Mervin C.; He, Johnny J.High-efficiency transduction of hematopoietic stem cells (HSCs) by recombinant adeno-associated virus serotype 2 (AAV2) vectors is limited by (i) inadequate expression of cellular receptor/co-receptors for AAV2; (ii) impaired intracellular trafficking and uncoating in the nucleus; (iii) failure of the genome to undergo second-strand DNA synthesis; and (iv) use of sub-optimal promoters. Systematic studies were undertaken to develop alternative strategies to achieve high-efficiency transduction of primary murine HSCs and lineage-restricted transgene expression in a bone marrow transplant model in vivo. These included the use of: (i) additional AAV serotype (AAV1, AAV7, AAV8, AAV10) vectors; (ii) self-complementary AAV (scAAV) vectors; and (iii) erythroid cell-specific promoters. scAAV1 and scAAV7 vectors containing an enhanced green-fluorescent protein (EGFP) reporter gene under the control of hematopoietic cell-specific enhancers/promoters allowed sustained transgene expression in an erythroid lineage-restricted manner in both primary and secondary transplant recipient mice. Self complementary AAV vectors containing an anti-sickling human beta-globin gene under the control of either the beta-globin gene promoter/enhancer, or the human parvovirus B19 promoter at map-unit 6 (B19p6) were tested for their efficacy in a human erythroid cell line (K562), and in primary murine hematopoietic progenitor cells (c-kit+, lin-). These studies revealed that (i) scAAV2-beta-globin vectors containing only the HS2 enhancer are more efficient than ssAAV2-beta-globin vectors containing the HS2+HS3+HS4 enhancers; (ii) scAAV-beta-globin vectors containing only the B19p6 promoter are more efficient than their counterparts containing the HS2 enhancer/beta-globin promoter; and (iii) scAAV2-B19p6-beta-globin vectors in K562 cells, and scAAV1-B19p6-beta-globin vectors in murine c-kit+, lin- cells, yield efficient expression of the beta-globin protein. These studies suggest that the combined use of scAAV serotype vectors and the B19p6 promoter may lead to expression of therapeutic levels of beta-globin gene in human erythroid cells, which has implications in the potential gene therapy of beta-thalassemia and sickle cell disease.Item P-039: Alternative Dosing and Prevention of Transfusions (Adapt): A Prospective Trial Evaluating Transfusion Utilization and the Feasibility of Pharmacokinetic Hydroxyurea Dosing in Children with Sickle Cell Anemia in Uganda(Wolters Kluwer, 2022-08-16) Power-Hays, A.; Namazzi, R.; Kato, C.; Conroy, A.; Hume, H.; John, C.; Stuber, Ma S.; Lane, A.; Latham, T.; Opoka, R.; Ware, R.; Pediatrics, School of MedicinePurpose: Blood transfusions are a scarce resource globally and particularly in sub-Saharan Africa. Without disease-modifying therapy, in sub-Saharan Africa sickle cell anemia (SCA) has excess morbidity, mortality, and healthcare resource utilization, specifically requiring a high reliance on blood transfusions. Hydroxyurea is a safe medication for the treatment of SCA that can decrease rates of blood transfusions. The widespread use of hydroxyurea in sub-Saharan Africa is limited in part, however, by logistical challenges in determining an individual patient’s optimal dose. Pharmacokinetic (PK) dosing of hydroxyurea may streamline the dosing process, maximizing the clinical benefits and minimizing toxicities, while reducing the time and resources needed to determine the optimal dose. We hypothesize that hydroxyurea treatment will be associated with a 50% reduction in blood transfusion rate in children with SCA, compared to pre-treatment utilization, and that determining a PK-based hydroxyurea starting dose will be feasible in 80% of participants. Materials and methods: To test this hypothesis, we will conduct the Alternative Dosing and Prevention of Transfusions (ADAPT) trial, a prospective cohort study of children with SCA in Jinja, Uganda (Figure). Transfusion rates and indications will be prospectively recorded during a 3-month pre-treatment period and compared to a 12-month treatment period. Every participant will undergo baseline hydroxyurea PK testing using timed serum collections based on our published sparse-sampling method and HPLC analysis. If generated, the participant will start on their PK-guided dose; when PK testing is not feasible, the participant will be started on 20 mg/kg/day per Ugandan guidelines. Regardless of starting dose (PK or default), all participants will undergo the same laboratory monitoring schedule with dose escalation and adjustments as necessary. Hydroxyurea will be purchased from a local commercial source using 500mg capsules. Results: The primary endpoint will be incidence rate ratio of transfusions per 100-patient years during hydroxyurea treatment as compared with the pre-treatment period. Based on sample size analysis, a total of 100 children with SCA (HbSS genotype), aged 1 to 10 years, will be enrolled in ADAPT. A student’s t-test will be performed to compare the rate of transfusions per 100 patient-years prior to and during hydroxyurea treatment. The secondary endpoints include feasibility of determining a PK-based starting dose and the rates of transfusions, clinical events, dose-limiting toxicities, and dose adjustments in participants on PK-based versus default start dose. Conclusion: Overall, the potential for hydroxyurea to reduce the rate of blood transfusions in children with SCA will have important individual and public health implications. Determining the feasibility and accuracy of PK-dosing of hydroxyurea could simplify the safe and effective treatment of SCA. ADAPT is a collaborative research partnership that will provide important data toward increasing the use of hydroxyurea in Uganda and potentially across sub-Saharan Africa.Item Provider Attitudes, Preferences, and Practices Regarding Sexual and Reproductive Health for Adolescents and Young Adults with Sickle Cell Disease(Elsevier, 2021) Leroy-Melamed, Maayan; Jacob, Seethal; Shew, Marcia L.; Kazmerski, Traci M.; Pediatrics, School of MedicinePurpose: With improvements in life expectancy, adolescents and young adults (AYAs) with sickle cell disease (SCD) increasingly face sexual and reproductive health (SRH) concerns. As subspecialists often serve as primary care providers for those with chronic disease, this study examines pediatric SCD providers' practices and attitudes related to SRH of AYA women with SCD. Methods: We developed an adapted survey to identify SCD provider attitudes and practices in addressing menses, sexual activity, contraception, and pregnancy for their female patients. We electronically distributed this survey to the American Society of Pediatric Hematology/Oncology SCD interest group. We used descriptive statistics to analyze results. Results: A total of 78 pediatric SCD providers completed the survey. A majority (95%) rated SRH discussions as moderately important or higher, with 89% agreeing this care should be standardized. Most respondents reported discussing SRH, such as menses (78%), teratogenic medications (61%), and contraception (90%), with their female patients with SCD at least annually. Although most refer AYAs with SCD for birth control (83%), 39% endorsed a preferred method, with 33% of these favoring levonorgestrel intrauterine devices in this population and 40% injectable contraception. Approximately half of respondents (57%) reported that the use of combined hormonal contraceptives was unacceptable despite published guidelines that support potential benefits outweighing theoretical risk in AYAs with SCD. Conclusions: The range of SRH conversations and contraceptive recommendations for AYAs from pediatric SCD providers is broad. SCD providers and AYAs with SCD would benefit from improved evidence and educational resources related to contraception as well as coordinated SRH counseling.Item Risk factors for recurrent severe anemia among previously transfused children in Uganda: an age-matched case-control study(Biomed Central, 2019-01-18) Dhabangi, Aggrey; Idro, Richard; John, Chandy C.; Dzik, Walter H.; Opoka, Robert; Ssenyonga, Ronald; van Hensbroek, Michael Boele; Pediatrics, School of MedicineBACKGROUND: In resource-poor settings, transfused children often experience recurrence of severe anemia (SA) following discharge from hospital. This study determined the factors associated with recurrent severe anemia (RSA) among previously transfused Ugandan children aged less than 5 years. METHODS: A case-control study was conducted in five hospitals in Uganda from March 2017 to September 2018. We prospectively enrolled 196 hospitalised children who had been transfused for severe anemia 2 weeks to 6 months prior to enrollment. Of these, 101 children (cases) were re-admitted with a hemoglobin [Hb] level of ≤6 g/dL and required transfusion; and 95 children (age-matched controls) were admitted for other clinical illness with a Hb > 6 g/dL. Children known to have sickle cell anemia, cancer, or bleeding disorders were excluded. Clinical and laboratory evaluation were done. Conditional logistic regression adjusted for age, was used to determine factors associated with RSA. RESULTS: The median time (IQR) between the earlier transfusion and enrollment was 3.5 (1.9-5.7) months for cases, and was 5.0 (2.9-6.0) months for controls (p-value = 0.015). Risk factors (adjusted odds ratio, 95% confidence interval, and significance) for development of RSA were: hemoglobinuria (36.33, 2.19-600.66, p = 0.012); sickle cell anemia - newly diagnosed (20.26, 2.33-176.37, p = 0.006); history of earlier previous transfusions (6.95, 1.36-35.61, p = 0.020) and malaria infection (6.47, 1.17-35.70, p = 0.032). CONCLUSION: Malaria chemoprevention, follow up visit for Hb check after discharge from hospital and sickle cell screening among previously transfused children represent practical strategies to prevent and identify children at risk for recurrent severe anemia. The cause of hemoglobinuria in children merits further investigations.