Abnormal Transcranial Doppler Ultrasound Research Articles

Impact of the 2014 NHLBI Hydroxyurea Guidelines on Cerebrovascular Events in Sickle Cell Disease

Background: Cerebrovascular disease (CVD) is a common cause of morbidity in patients with sickle cell disease (SCD). An estimated 37% of children with SCD have silent cerebral infarcts (SCI) by age 14, leading to increased stroke risk and neurocognitive impairment. In the DISPLACE trial (Kanter et al, 2021), 2.9% of patients had abnormal cerebral blood flow as measured on transcranial Doppler ultrasound (TCD). The 2014 National Heart, Lung, and Blood Institute (NHLBI) guidelines recommend hydroxyurea (HU) for all patients with SCD-SS and SCD-Sβ 0 starting at age 9 months, a significant shift from prior practice. In patients who have already developed TCD abnormalities, HU is protective against stroke and CVD progression. The real-world impact of universal early HU on the development of CVD, particularly on SCI, is not well defined . We hypothesize that the 2014 guidelines led to an increase in HU use and a reduction in the initial development of CVD. Methods: We performed a single center, retrospective cohort study investigating trends in HU prescriptions and CVD before and after the publication of the 2014 NHLBI guidelines. Patients with SCD-SS and SCD-Sβ 0 who initiated hematology care at the Children's Hospital of Philadelphia between 2009 and 2023 were identified using an institutional registry. Incident HU was defined as the first outpatient HU prescription in patients with a minimum of two orders. Incident CVD was defined as a composite outcome consisting of the first documentation of: abnormal TCD, brain magnetic resonance imaging (MRI) with silent infarct, or overt ischemic stroke. Patients with known CVD before care initiation, prematurity < 28 weeks gestational age, or non-SCD neurologic disease were excluded. For time-to-HU analysis, patients with HU prescriptions before enrollment at our center also were excluded. Patients were followed from their first hematology visit until the outcome of interest or censoring. Censoring criteria included loss to follow up, transition of care, or bone marrow transplant. All brain MRI and TCD reports were manually reviewed. Ages at HU initiation pre- and post- guideline were compared using the Wilcoxon rank-sum test . Times to 1) HU and 2) CVD were summarized using Kaplan-Meier estimators, with the guideline publication date of September 1, 2014 incorporated as a time-varying exposure. Unadjusted associations were calculated using a Cox proportional hazard regression. Results: A total of 446 patients met inclusion criteria and contributed to analyses. Median age at baseline was 2.4 months, and median duration of follow-up was 5.0 years (IQR: 2.3-8.7). Most patients (430/446, 96%) had SCD SS, and 51% were male. The proportion of patients ever prescribed HU increased with time (Fig 1), with a peak prevalence of 82% in 2022. Of 385 patients not exposed to HU at baseline, 277 (72%) were prescribed HU during study follow-up. Incident HU prescriptions significantly increased after NHLBI guideline publication (HR 3.40, CI: 2.50 to 4.63, p < 0.001) with an older age at HU initiation before (median 4.0 y, IQR 2.5-7.7) than after (median 2.9 y, IQR 1.1-5.8) publication of the guideline (p = 0.002). Over a total of 2,395 person-years of follow-up, 66 incident CVD outcomes occurred in this longitudinal cohort, corresponding to a cumulative incidence of 14.8%. These events included 53 SCI, 10 abnormal TCD, and 3 overt ischemic strokes. CVD outcome occurrence was lower after guideline publication than before (HR 0.58, CI: 0.32-1.05), though the association did not reach statistical significance (p = 0.071, Fig. 2). Discussion: After the NHLBI guideline publication, HU prescriptions increased significantly at our center.Our data suggest that the 2014 guideline-directed care may have led to a greater than 40% reduction in CVD, though this reduction was not statistically significant in our small sample size. Despite guideline recommendations and strong evidence for the role of HU in reducing pain and acute chest syndrome, few patients across the United States are prescribed HU therapy. Adherence and care continuity challenges further lessen the number of patients benefitting from HU. Evidence of efficacy of early and universal HU in CVD prevention would strengthen guideline recommendations and improve clinical care in patients with SCD. Ongoing analysis includes an expanded cohort and adjustment for clinical covariates to better examine the direct impact of early HU on CVD.

Successful Implementation Trial to Improve Stroke Risk (TCD) Screening in Children with Sickle Cell Anemia: A Roadmap to Care Enhancement

Stroke remains a devastating complication of sickle cell anemia (SCA). The STOP (Stroke Prevention Trial in Sickle Cell Anemia) protocol adopted in 2014 by the National Heart Lung and Blood Institute (NHLBI) guidelines includes stroke-risk screening using transcranial Doppler ultrasound (TCD) and prevention with chronic red cell transfusion therapy (CRCT). Theserecommendations were reinforced by the American Society of Hematology guidelines.However, despite the evidence supporting TCD screening in stroke prevention, the DISPLACE study (Dissemination and Implementation of Stroke Prevention Looking at the Care Environment) showed that real-world implementation was insufficient. To evaluate and improve sickle stroke screening, we conducted the NHLBI-funded multi-center DISPLACE study to identify barriers to TCD implementation and test novel methods for improving outcomes. DISPLACE is a 4-part study: 1) Retrospective calculation of TCD screening rates; 2) Assessment of barriers and facilitators; 3) Implementation trial to improve TCD screening and 4) Comparison of implementation sites to controls. Importantly, DISPLACE is the largest prospective study of children with SCA. This study employed a multi-level, multi-faceted cluster-randomized study of interventions to improve implementation rates of TCD. Methods: DISPLACE is a 28-center US consortium representing a range of: regions (urban vs rural), size (patient number), and institution type (academic vs community). In Part 1, sites performed a rigorous retrospective review of TCD screening from 2012-2016 to collect baseline rates. Part 2 included a barriers and facilitators assessment to TCD screening to inform the trial interventions: 1) Re-branding TCD as Sickle Stroke Screen, a meaningful name for SCD stakeholders; 2) Using a Single Coordinator (SC) for each site's TCD scheduling, and follow-up; 3) A custom designed provider-focused application, ProviderMinder TM (PM) created to remind providers to track TCD appointments and follow-up on results. When a TCD was due, PM alerted the provider to enter scan results or reason(s) missed. Once the TCD results (normal/conditional/abnormal) were entered in PM, providers were prompted to enter the next TCD date and/or intervention plan (if not normal). If a result was not entered, PM alerted the provider q3 days until the TCD was recorded as completed or rescheduled. The implementation trial (parts 3 and 4 of DISPLACE) included 16 sites that had the lowest TCD rates in part 1. The implementation trial included children with SCA aged 2-7 years (the group at highest risk for an abnormal TCD). Cluster randomization was used to allocate sites to PM alone (8 sites) or PM + SC (8 sites). The primary outcome was comparison of TCD rates between PM and PM+SC sites. Secondary outcomes included comparisons between 1) Part 3 sites' TCD rates and Part 1 baseline rates 2) Part 3 sites and control sites (to assess the impact of the educational rebranding of TCD). Results: Part 1 included 28 centers with 5246 children with SCA. Of the 16 intervention sites, 3 sites could not implement the interventions due to administrative issues but remained in the study and were re-designated as “control sites” and a 4th control site was added (they were not informed prospectively to avoid bias). Thus, there were 13 evaluable sites for the primary endpoint including 776 patients; 484 in sites using PM and 292 in sites using PM+SC. Control sites included 185 patients. The trial demonstrated superiority of the PM arm compared to the PM + SC arm (P<.0001 year 1 and p=0.002 year 2) in both years of implementation and in comparison, to the control sites (P<.0001 year 1, p=.009 year 2) with an overall improvement in mean TCD screening from part 1 by 25% (table 1). Conclusions: This was a highly successful implementation study in SCA. This study emphasizes the importance of performing barrier and facilitator assessments when introducing new guideline-recommended screenings into clinical practice. These findings also highlight the importance of ongoing quality assurance in SCA to ensure prevention practices are maintained. Despite the benefit of TCD (sickle stroke screening) in children with SCA, implementation was poor prior to these interventions. Results from this study will guide ongoing optimization of TCD screening and demonstrate the importance of adopting these interventions in the real world.

Dissemination and Implementation Looking at the Care Environment (DISPLACE) Study Evaluates Novel Interventions to Improve TCD (Sickle Stroke Screening) Implementation

Background: Stroke is a devastating complication of sickle cell anemia (SCA). The STOP (Stroke Prevention Trial in Sickle Cell Anemia) protocol was adopted in 2014 by the National Heart Lung and Blood Institute (NHLBI) guidelines for stroke-risk screening using transcranial Doppler ultrasound (TCD) and prevention with chronic red cell transfusion therapy (CRCT). These guidelines were upheld in the recent American Society of Hematology guidelines. Despite strong evidence supporting TCD screening (and CRCT initiation) in stroke prevention, wide scale implementation has not been achieved 4. DISPLACE (Dissemination and Implementation Looking at the Care Environment) is a multicenter, NHLBI-funded study conducted to identify barriers to TCD implementation and test novel methods for improving outcomes. DISPLACE is a 3-part study: 1) Retrospective assessment of current practice; 2) Assessment of barriers and facilitators; and 3) Implementation trial to improve TCD screening. This report focuses on Part 3. Methods: DISPLACE is a 28-center consortium across the US representing a range of: region (urban vs rural), size, and institution type (academic vs community). During Part 1, sites performed a rigorous retrospective chart review of children with SCA aged 2-16 years from 2012-2016 to collect baseline TCD rates. Part 2 included a rigorous mixed methods of the barriers and facilitators assessment to TCD screening was performed that resulted in 3 main interventions: 1.Re-branding TCD as Sickle Stroke Screen, a meaningful name selected by patients/families with SCD; 2. A Single Coordinator (SC) for each site's TCD screening, scheduling, and follow-up; 3. A newly designed application, Provider Minder (trademarked; PM). PMwas created to remind providers of patient appointments (versus reminders only sent to patients/families). Data entry in PM included birth date (to calculate age), city/state of residence, distance from SCD clinic and insurance. Date of last TCD was recorded to calculate date of next screen. When the TCD was due, the system alerted the provider to enter appointment completion or reason(s) why it was missed. TCD results were entered for PM to prompt for the next TCD date in a 10-14 month window (normal screens), 2-6 weeks (conditional screens), and intervention plan (abnormal screens): repeat scan in <2 weeks or other. If the provider failed to enter a patient's result, PM alerted the provider q3 days until the TCD was recorded as completed/rescheduled. Part 3 included 16 sites who successfully completed data entry in Part 1 and had the lowest TCD implementation rates. Part 3 inclusion criteria were the same as Part 1 except to specifically select children with SCA now aged 2-7 (the highest risk group to have an abnormal TCD in Part 1). All 28 sites received re-branding educational material (also disseminated to non-study sites). Cluster randomization was used to allocate sites to PM (8 sites) or PM + SC (8 sites). The primary outcome is which intervention results in the best TCD rates. Secondary outcomes include Part 3 sites’ improvement in TCD rates (compared to historical rates) and impact of the educational/rebranding of TCD to "Sickle Stroke Screen” in sites (4) that did not participate in Part 3. Stroke status, presence of CRCT after an abnormal TCD, missed TCD appointments, and medical decisions following TCD were also recorded. Results: Part 1 included 28 centers with 5223 individuals with SCA in the database. Of the 16 Part 3 sites, three could not implement the interventions due to a simultaneous change in hospital administration and site PI (1), inability to use PM due to institutional firewall (1) and inability to implement due to site specific issues (1). These 3 sites remained in the study as "control sites” and a fourth control site was added. Thus, 13 sites implemented the interventions with 877 patients; 520 were in sites using PM and 357 were in sites using PM+SC. Demographic data for the 877 children with SCA are in Table 1. The study ended on May 31, 2022. Calculations of TCD rates at all sites are in process and will be presented. Conclusions: Despite the benefit of TCD screening in children with SCA, guideline-based implementation remains poor. The range of barriers to screening has been previously reported by the DISPLACE study team and were used to design the study interventions. Results from this study will guide optimization of the intervention protocol proven to enhance TCD implementation. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Association Between Patent Foramen Ovale and Overt Ischemic Stroke in Children With Sickle Cell Disease

Ischemic stroke is one of the most devastating complications of sickle cell anemia (SCA). Previous studies have shown that intracardiac shunting including patent foramen ovale (PFO) can be a potential risk factor for stroke in children with SCA. This study investigates the association between PFO and overt ischemic stroke in the DISPLACE (Dissemination and Implementation of Stroke Prevention Looking at the Care Environment) study cohort of 5,247 children with SCA of whom 1,414 had at least one clinical non-contrast transthoracic echocardiogram. Presence of PFO was taken from the clinical report. Further, we assessed the association between PFO and other clinical and hemolytic factors in children with SCA such as history of abnormal sickle stroke screen [elevated Transcranial Doppler ultrasound (TCD) velocity] and patient's baseline hemoglobin. In 642 children for whom all data were available, the adjusted odds ratio (OR) for overt stroke was higher in those with PFO but this was not statistically significant (OR: 1.49, 95% CI: 0.20–11.03, p = 0.6994). With an OR of 0.85, the study suggested less PFOs in those with abnormal TCD, but this was not statistically significant (95% CI: 0.17–4.25, p = 0.8463). Overall, the prevalence of PFO in this large sub study of non-contrast echocardiography amongst children with SCA is much lower than previous smaller studies using bubble contrast echocardiography. Overt stroke was non-statistically more common in children with SCA and PFO, but there was no evidence that PFO was more common in those with abnormal TCD, the most important pediatric sickle stroke screen.

Transcranial Doppler Ultrasonographic Evaluation of Cerebrovascular Abnormalities in Children With Acute Bacterial Meningitis.

Introduction: Bacterial meningitis (BM) is a global public health concern that results in significant morbidity and mortality. Cerebral arterial narrowing contributes to stroke in BM and may be amenable to intervention. However, it is difficult to diagnose in resource-limited settings where the disease is common.Methods: This was a prospective observational study from September 2015 to December 2019 in sub-Saharan Africa. Children 1 month−18 years of age with neutrophilic pleocytosis or a bacterial pathogen identified in the cerebrospinal fluid were enrolled. Transcranial Doppler ultrasound (TCD) of the middle cerebral arteries was performed daily with the aim to identify flow abnormalities consistent with vascular narrowing.Results: Forty-seven patients were analyzed. The majority had Streptococcus pneumoniae (36%) or Neisseria meningitides (36%) meningitis. Admission TCD was normal in 10 (21%). High flow with a normal pulsatility index (PI) was seen in 20 (43%) and high flow with a low PI was identified in 7 (15%). Ten (21%) had low flow. All children with a normal TCD had a good outcome. Patients with a high-risk TCD flow pattern (high flow/low PI or low flow) were more likely to have a poor outcome (82 vs. 38%, p = 0.001).Conclusions: Abnormal TCD flow patterns were common in children with BM and identified those at high risk of poor neurological outcome.

Evaluation of STOP Protocol Implementation for Abnormal TCD in Children with Sickle Cell Anemia at Risk for Stroke: Displace Consortium

Introduction: Without intervention, children with sickle cell anemia (SCA) have an 11% chance of overt ischemic stroke. The Stroke Prevention Trial in Sickle Cell Anemia (STOP) proved that children with SCA at increased risk of stroke can be identified using transcranial Doppler ultrasound (TCD) and, for those at risk, chronic red cell transfusion (CRCT) therapy is effective at preventing stroke. The 2014 National Heart, Lung, and Blood Institute (NHLBI) guidelines include annual TCD screening for children with SCA ages 2 - 16, and CRCT for primary and secondary ischemic stroke prevention. The NHLBI-funded Dissemination and Implementation of Stroke Prevention Looking at the Care Environment (DISPLACE) project was designed to 1.) evaluate current stroke screening and prevention practices in a 28-site consortium through intensive medical record review and an electronic data capture system, 2.) determine barriers and facilitators to stroke prevention practices through qualitative methods, and 3.) design and deliver interventions to increase rates of 'sickle stroke screening' using implementation strategies. The purpose of this abstract is to describe initial (pre-study) consortium actions following abnormal TCD results including whether all children had a repeat TCD within the next 4 weeks, whether they initiated CRCT, characteristics of which children received CRCT, and what alternate treatments were used. Methods: DISPLACE data collection years were 2012 - 2016. 5247 children with SCA who met criteria for annual TCD screening were entered into the electronic data capture system with clinical and demographic information. 163 children with abnormal TCD results were identified from the cohort database. Additional data were collected and subsequently adjudicated including timing of follow-up testing (repeat TCD or MRI) after abnormal TCD, implementation of CRCT following abnormal TCD, alternate treatment following abnormal TCD, and whether the STOP protocol was implemented. Data were analyzed using descriptive statistics. Results: In response to abnormal TCD, 75% of children had a repeat TCD ordered (Table 1). Of these, most repeat TCDs were completed within 3 months, with &amp;lt;10% delayed (longer than 12 weeks). CRCT was initiated in 69% of children with abnormal TCD (Table 2); of these, 17% had delayed initiation of CRCT. After abnormal TCD, 10% of families declined CRCT though suggested by providers. When some of these children later suffered an ischemic stroke, (20%) started CRCT at that time. The TWiTCH protocol (CRCT transitioning to HU in children without severe vasculopathy) was followed in about 1/4 of children on CRCT. Additional treatments following abnormal TCD included initiation of HU (64%) and bone marrow transplant (4%) (Table 3). Characteristics of children on CRCT are described in Table 4. Notably, of the 19 children whose CRCT was delayed, 15 (79%) had a stroke. There were 48 instances in which the STOP protocol was not implemented following abnormal TCD. Half of these were the result of decisions at the parent level (e.g., the parent refused CRCT, parent requested HU instead of CRCT). Five were provider decisions (e.g., provider suggested HU), and 15 were systems-level issues (e.g., repeat TCD was delayed). One was a combination of parent decision and system-level issue, and in 4 cases, the reason was unknown. Conclusions: In this nationally representative sample of children with SCA at risk for stroke, nearly ¾ of children had a repeat TCDs, suggesting confirmation of abnormal results was common prior to beginning CRCT. Notably, there were a large number of ischemic strokes in children when CRCT was delayed futher confirming the utility of the screening and stroke prevention protocol. An additional key concern identified in this study were the barriers to STOP protocol implementation. Common reasons for lack of implementation included the parent's decision for HU instead of CRCT, delays in CRCT initiation, and delays in obtaining repeat TCDs. Difficulties implementing the STOP protocol suggest the need for interventions for more rapid initiation of CRCT and stroke prevention. Disclosures Kanter: AGIOS: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; Sanofi: Consultancy; bluebird bio, inc: Consultancy, Honoraria; Medscape: Honoraria; Guidepoint Global: Honoraria; GLG: Honoraria; Jeffries: Honoraria; Cowen: Honoraria; Wells Fargo: Honoraria; NHLBI Sickle Cell Advisory Board: Membership on an entity's Board of Directors or advisory committees; SCDAA Medical and Research Advisory Board: Membership on an entity's Board of Directors or advisory committees; BEAM: Membership on an entity's Board of Directors or advisory committees.

Practice patterns for neuroimaging and transfusion therapy for management of neurologic complications in sickle cell anemia: DISPLACE consortium.

Children with sickle cell anemia (SCA) are at risk for neurologic complications (stroke and silent cerebral infarct). The 2014 National Heart, Lung, and Blood Institute (NHLBI) guidelines for sickle cell disease include recommendations for initiation and maintenance of chronic red cell transfusion (CRCT) therapy for children with SCA at risk for or with ischemic stroke. The guidelines do not include well-delineated recommendations for cerebral imaging for stroke screening. The purpose of this study was to evaluate current stroke risk screening, prevention, and intervention practices amongst the Dissemination and Implementation of Stroke Prevention Looking at the Care Environment (DISPLACE) study sites. A survey was administered to DISPLACE site principal investigators to identify current stroke prevention practices relative to the Stroke Prevention Trial in Sickle Cell Anemia (STOP) study protocols and the 2014 NHLBI guidelines. Data were analyzed using descriptive statistics and line-by-line analysis of comments. Sites consistently applied NHLBI recommendations to initiate CRCT for ischemic stroke and abnormal transcranial Doppler ultrasound (TCD) results. Similarly, nearly all sites reported obtaining an magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) following an abnormal TCD result. There was wide variation for other indications for MRI/MRA, frequency of MRI/MRA, and other neurological indications for initiating CRCT. Guideline-based practices for preventing ischemic stroke through TCD and CRCT initiation were evident in nearly all sites. Wide variation in practices pertaining to MRI/MRA exists, potentially influenced by more recent stroke prevention trials. New guidelines from the American Society of Hematology were published in April 2020, which may reduce practice variation.

Characteristics of Children with Abnormal TCD in the Modern Era: Results from the Displace Consortium

Background: Stroke is one of the most devastating complications of sickle cell anemia (SCA). In 1998, the Stroke Prevention Trial in Sickle Cell Anemia (STOP), demonstrated that a high-risk group of children with SCA could be identified using Transcranial Doppler ultrasound(TCD) and that chronic red cell transfusion therapy (CRCT) could reduce the risk of first ischemic stroke in this group by over 90% (Adams, et al NEJM 1998).At STOP studyenrollment, 9.7% of children with SCA were identified as having an abnormal TCD. Baby HUG, (NCT00006400), an NHLBI supported phase III trial showed that severe anemia in SCA was associated with elevated white blood cell (WBC) and higher TCD velocities (Lebensburger, et al Blood 2010 ). It is unclear if lower hemoglobin (Hb) and/or higher WBC are causative of elevated TCD velocities or correlative biomarkers. As new disease therapies become available, it is important to know the current rate of abnormal TCD and characteristics of those patients. The DISPLACE (Dissemination and Implementation Looking at the Care Environment) project is a multicenter, NHLBI-funded study whose primary purpose is to identify barriers to implementation of stroke screening in SCA and test novel methods for improving outcomes. DISPLACE is a 3-part study: retrospective assessment of current practice, qualitative review of barriers and facilitators to screening and a cluster-randomized intervention implementation project to improve stroke screening. Part 1 of the study showedthat TCD screening rates varied widely among institutions ranging from 30-75.2% (mean 48.4%, median 47%). We are now reporting on the rate of abnormal TCD and the characteristics and outcomes of patients with abnormal TCD. Methods: DISPLACE is a consortium of 28 US centers. Each site performed a rigorous retrospective chart review of children with SCA aged 2-16 years from 2012-2016. To be eligible for inclusion, children must have been seen at their institution at least 2x during the study period and have confirmation of SCA. A custom electronic data capture (EDC) system facilitated entry of de-identified data including demographics, TCD and MRI results, medications, transfusions, and laboratory values. For children with SCA who had TCD or central nervous system imaging prior to 2012, these results were also entered into the EDC. TCD results were recorded in the EDC as normal, conditional or abnormal based on their institutional interpretation. Labs and vitals were entered for each patient in closest proximity to each TCD. Confirmation and adjudication of each abnormal TCD and associated outcomes were performed. Stroke status was also recorded as well as presence or absence of CRCT. Results: In total, 5247 children with SCA are included in the database of whom 5225 should have received a TCD. Of this cohort, 4210 children (80.6%) had at least one TCD recorded in the database. Within this group, 207 (4.9%) of children had an abnormal TCD and 816 (19.4%) had a conditional TCD. For those children who underwent TCD during the study (2012-2016) period, there were 105 (2.9%) abnormal TCD and 501 (13.6%) conditional TCD (Table 1). The mean age of children at the time of abnormal TCD was 6.6 years (range 2-16 yr). The majority of children were &lt;10 yr at first abnormal TCD. Over 30% of patients with an abnormal TCD were identified as receiving hydroxyurea.The mean Hb associated with an abnormal TCD was 7.8 +/- 1.1g/dl (range 5.7-10.6) and the mean WBC was 13 x109/L+/- 3.6 (range 3.9-23.4) (Table 2). Of the 105 patients with abn TCD during the study period, 18% had a stroke. Of the total 5247 patients in the database, 3093 (59%) had been prescribed hydroxyurea (HU) and 999 (19%) were prescribed CRCT. CRCT was prescribed most often for abnormal TCD (37%) or secondary stroke prevention (31%). Discussion: DISPLACE is the largest contemporary cohort of children with SCA. The incidence of abnormal TCD in the DISPLACE cohort is significantly lower than at randomization in the STOP study. The number of children receiving CRCT is higher than expected which may partly account for the decrease in frequency of abnormal TCD. Many patients with abnormal TCD were receiving HU when their TCD was abnormal and were started on CRCT. Additionally, while the outcomes of children with conditional TCD are still being evaluated, many of those children reverted to normal TCD without intervention. These data may also help us redefine the use and interventions needed for abnormal TCD. Disclosures Kanter: NHLBI: Membership on an entity's Board of Directors or advisory committees; bluebird bio, Inc.: Consultancy; SCDAA: Membership on an entity's Board of Directors or advisory committees; Guidepoint Global: Consultancy; GLG: Consultancy; Sangamo: Consultancy, Honoraria; Modus: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Imara: Consultancy; Cowen: Consultancy; Jeffries: Consultancy; Medscape: Honoraria; Rockpointe: Honoraria; Peerview: Honoraria. Adams:GBT: Consultancy, Other: consultancy to companies GBT and Blueburd Bio; Bluebird: Consultancy.

Association between Inflammatory Markers and Abnormal Neurological, Neurocognitive and Magnetic Resonance Imaging (MRI) Findings in Children with Sickle Cell Anemia in Uganda

Background: Children with sickle cell anemia (SCA) are highly susceptible to stroke and other manifestations of pediatric cerebral vasculopathy. Inflammation is a risk factor for acute stroke. In a cross-sectional study of Ugandan children, we asked whether inflammatory markers correlated with findings on neurological and neurocognitive testing and magnetic resonance imaging (MRI). Methods: Stored plasma samples were obtained at a well study visit from 81 children, a subset within a larger sample of study participants with HbSS ages 1-12 years recruited at the Mulago Hospital sickle cell clinic in Kampala. Participants underwent 4 standardized assessments: neurocognitive testing using the Mullen Scales of Early Learning (for ages 1-4 years) or Kaufman Assessment Battery for Children, 2nd edition (for ages 5-12) (abnormal at z-score of -2 or lower), examination for prior stroke (PedsNIHSS) and transcranial Doppler ultrasound (TCD) using criteria for pediatric SCA, plus a non-contrast MRI/MRA on a 1.5 Telsa scanner, analyzed for T1- and T2- weighted images and T2 FLAIR. MR scans were interpreted by clinical and research methods, the latter per SWiTCH protocol (Helton, Blood 2014). Adjudication of differing reads was performed by a blinded third neuroradiologist. Participants undergoing MRI intentionally included 29 without any abnormal findings on the three other evaluations. Plasma samples were examined for key cytokines and markers of vascular activation by a 20-plex Luminex immunoassay. Immune markers included IL1b, IL1RA, IL2, IL4, IL10, IL18, IL22, IFNg, TNFa, TNFb, sFasL, CXCL1, CXCL8 (IL8), PDGFBB, VEGFA, serpin E1 (Plasminogen Activator Inhibitor (PAI)-1), sICAM1, VCAM1, TGFa, plus assay of hsCRP. Raw immune data were transformed using Box-Cox transformations and standardized; markers with persistently skewed (non-Gaussian) distributions after transformation were dichotomized for analysis. Continuous immune variables were analyzed by repeated measures ANOVA (unadjusted) and ANCOVA (adjusted for baseline covariates of age, sex, hemoglobin and 25-hydroxy-vitamin D3/D2. Dichotomized biomarkers were analyzed using generalized linear mixed-effects models. For these exploratory biomarker discovery-focused analyses, all significance tests were performed 2-tailed without adjustment for multiple comparisons, with a=0.1 for main effects. Results: Mean age was 6.48 ± 2.75 years, 50.6% male. Mean hemoglobin was 7.26±0.90 g/dl; 16.7% were malnourished using standard international measures established for age and sex. Infarcts on MRI were detected in 42 (52%), including 13 (25%) with no other test abnormalities. Of the 20 inflammatory markers tested, the levels of 13 markers were associated with one or more abnormality. One or more infarcts on MRI as the sole abnormality ("silent" stroke) were associated with levels IL1b, IL2 and TGFb (Table 1). Neurocognitive dysfunction alone was associated only with levels of IL22. Abnormal TCD (primarily "conditional" values) or prior stroke was associated with levels of VEGFA, IL4 and TNFb. In contrast, abnormal TCD or stroke by examination plus neurocognitive dysfunction was associated with nine cytokines levels: CXCL8, CXCL1, IFNg, TNFa, sFasL, IL18, IL22, sICAM1 and VEGFA. In all cases, cytokine levels were negatively associated with each of the abnormal neurological, neurocognitive or imaging results. Adjusting for age, sex, hemoglobin and malnutrition had only modest effects on statistically significant results. No associations were found between the test results and any of the other eight inflammatory markers, including hsCRP. Conclusions: In this exploratory biomarker analysis in a sample with highly prevalent abnormal test results, the presence of those abnormalities correlated with levels of a majority of the inflammatory markers assayed. The clinically well status at sampling and the finding of lower markers levels associated with existing abnormalities suggest that these children were not currently inflamed. As a cross-sectional analysis, cerebral vasculopathy underlying those abnormalities had previously occurred. Lower levels of inflammation may reflect a survivor status of children affected by a chronic illness with high local mortality. Our findings need to be confirmed in a prospective study children, and may be most interesting at acute events and for subjects receiving disease-modifying therapy. Disclosures No relevant conflicts of interest to declare.

Plasma BDNF Levels Are Associated with Stroke in Children with SCD

Background: Cerebrovascular disease, particularly overt stroke, is one of the most critical clinical complications of sickle cell disease (SCD). Individual stroke risk for patients with SCD is assessed by measuring trans-cranial Doppler ultrasound (TCD) velocity. While TCD screening and resulting use of chronic blood transfusion therapy in patients with abnormal TCDs has reduced stroke incidence in patients with SCD from 11% to 1%, the test has significant limitations. It can only be performed on children old enough to remain still for the assessment, or young enough to have open bony windows; typically 2-16 years of age. Additionally the test has poor positive predictive value, causing patients to be placed on chronic transfusion therapy who would not have gone on to have a stroke. Hydroxyurea (HU) is replacing chronic transfusion therapy in many institutions for primary stroke prevention, but many sites initiate a "cooling off" period of transfusions prior to initiating HU, and transfusion therapy may be indicated for abnormal TCD velocities in patients already on HU. The pathophysiology of stroke in SCD patients is not completely understood, but vascular remodeling, abnormal cerebral blood flow, and vaso-occlusion all play a role. Plasma levels of Brain derived neurotrophic factor (BDNF), myeloperoxidase (MPO), vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) have been shown to be associated with high trans-cranial Doppler ultrasound (TCD) velocity in children with SCD; but there is limited data on their potential association with stroke in this population. BDNF is a neurotropin that is responsive to hypoxia and promotes neurogenesis as well as playing a key role in the regulation of the cell survival pathway; myeloperoxidase (MPO) promotes vascular injury by oxygen radical generation, leukocyte/neutrophil recruitment, and oxidative stress; vascular cell adhesion molecule 1 (VCAM-1) is and endothelial adhesion molecule involved in the pathophysiology of vaso-occlusion in SCD through promoting RBC adhesion; and intercellular adhesion molecule 1 (ICAM-1) is expressed on endothelial and immune system cells and is thought to be a ligand for leukocyte adhesion. We hypothesized that BDNF, MPO, VCAM-1 and ICAM-1 may be involved in stroke in SCD, and may be potential biomarkers to be used to assess an individual with SCD's stroke risk in addition to TCD. Methods: We collected plasma samples from the peripheral blood of fifteen SCD patients (HbSS) at the time of either silent cerebral infarct (SCI) or stroke. Stroke (n=8) or SI was confirmed by MRI using diffusion imaging and T2 FLAIR. The cohort included 6 females and 9 males between the ages of 3 and 20 years. Plasma from fifteen age and gender matched control patients with HbSS but had normal MRIs and TCD velocities less than 170 m/s. We measured plasma levels of BDNF, MPO, VCAM-1 and ICAM-1 using antibody immobilized fluorescent beads (Millipore, Billerica, MA) and Luminex xMAP technology (Bio-Rad, Hercules, CA). Student's t-test was used to analyze the difference in plasma levels between the stroke and control groups. Results and Conclusions: BDNF levels were significantly higher in the stroke group than in the control group; 2978.2 ± 960.3 pg/ml compared to 2200.8 ± 758.4 pg/ml, p=0.005. Difference in MPO levels between the two groups approached significance; 36617.2 ± 14828.9 pg/ml compared to 29521.9 ± 7889.6 pg/ml, p=0.07. Difference in VCAM-1 levels also approached significance; 143997.0 ± 9963.8 pg/ml compared to 138126.9 ± 11902.0 pg/ml, p=0.08, but there was no significant difference in ICAM-1 levels. Only BDNF plasma levels positively correlated with the area and volume of the infarct, p=0.009. These results further support the assertion that BDNF is involved in the pathophysiology of cerebrovascular disease in SCD. It is possible that MPO and VCAM-1 may also play a role, and that a significant difference was not found due to sample size limitations. Plasma BDNF levels, and possibly MPO and VCAM-1 plasma levels, have potential as biomarkers for stroke risk to improve the positive predictive value of TCD velocities in patients with SCD, or to assess risk in patients unable to receive TCDs. Disclosures No relevant conflicts of interest to declare.

Radiological Findings By Magnetic Resonance (MRI) and Arteriography (MRA) Brain Imaging Compared to Neurological, Stroke and TCD Assessment in Children with Sickle Cell Anemia in Uganda

Background: Children with sickle cell anemia (SCA) are highly susceptible to stroke and other manifestations of pediatric cerebral vasculopathy. Detailed evaluations of children with SCA in sub-Saharan Africa are limited, especially magnetic resonance imaging and angiography (MRI/MRA). In a sample of Ugandan children receiving care at the Mulago Hospital sickle cell clinic in Kampala and were not on disease-modifying therapy, we examined the range of MR imaging findings, and how those findings correlated with standardized demographic, clinical, neurological and neurocognitive assessments. Methods: From within a larger sample of 265 participants with HbSS ages 1-12 years not taking disease-modifying therapy and enrolled in the BRAIN SAFE study, a sub-sample of 81 underwent non-contrast MRI/MRA on a 1.5 Telsa scanner. Participants also underwent 3 standardized assessments: neurocognitive testing by experienced testers using the Mullen Scales of Early Learning (for ages 1-4 years) or Kaufman Assessment Battery for Children, 2nd edition (for ages 5-12) (abnormal z-score of -2 or lower), stroke examination (PedsNIHSS) and transcranial Doppler ultrasound (TCD) using criteria for pediatric SCA. Participants undergoing MRI/MRA intentionally included 29 without any abnormal findings. MRI scans included T1- and T2- weighted images, T2 FLAIR and MRA three-dimensional time-of-flight technique. MR scans were interpreted by clinical and research methods, the latter per SWiTCH protocol (Helton, Blood 2014). Adjudication of differing reads was performed by a blinded third neuroradiologist. Results: A total of 81 children with SCA were examined by MRI/MRA. Mean age was 6.48 ± 2.75 years; 50.6% were male. Mean hemoglobin was 7.26±0.90 g/dl; 75% had hemoglobin &lt;8.0. In all, 16.7% were malnourished using standard international measures established by age and sex. Infarcts and/or arterial stenoses on MRI/MRA were detected in 42 (52%), including 13 (25%) with no other abnormalities detected. There were 35 children (43.2%) who had medium or large infarcts seen; an additional 16 (19.8%) had 1-2 small infarcts. Four had moya moya. Of the 29 children categorized as normal on each of the 3 other tests, 14 (48.3%) had one or more medium or large infarct(s) on MRI, and 3 (10.3%) had 1-2 small infarcts (Figure 1). The proportion of children with malnutrition was higher among those with an abnormal MRI compared to those with a normal MRI, whereas no children with a small infarct was malnourished (29.4% vs. 10.7% vs. 0% p=0.019). A higher proportion of participants with stroke by exam had medium or large infarct(s) compared to participants with normal or small infarct (28.6% vs. 10% vs. 6.3%; p=0.061). Stroke on exam was associated with medium or large infarct(s) compared to normal or small infarct (unadjusted OR 4.2; 95% CI 1.19-14.8), and remained after adjusting for age and hemoglobin (OR 3.90 95%CI 1.10-13.9). The proportion of abnormal psychological testing was higher in the small infarct group than in the group with larger infarct(s) or the normal group (37.5% vs. 28.6% vs. 17.2%; p=0.307). Conclusion: High prevalence of pediatric cerebral vasculopathy was found on MR scanning. Despite clinical evidence suggesting abnormal neuropsychological testing or a prior stroke, not all of the children who had clinical evidence of neurological disorders had MRI evidence of a stroke. Additionally, a number with no evidence of stroke had infarct(s) on MRI, so-called "silent stroke." The strongest predictors of an abnormal MRI reading included having a detectable stroke or an abnormal TCD. MR imaging is a critical aspect of evaluating cerebral vasculopathy in this patient population, and will be an important measure when prospectively assessing impact in a treatment trial. Disclosures No relevant conflicts of interest to declare.

Ischemic stroke in children and young adults with sickle cell disease in the post-STOP era.

The Stroke Prevention Trial in Sickle Cell Anemia (STOP) and Optimizing Primary Stroke Prevention in Sickle Cell Anemia (STOP 2) trials established routine transcranial Doppler ultrasound (TCD) screening, with indefinite chronic red cell transfusions (CRCT) for children with abnormal TCD as standard of care. Implementation failures and limitations to the STOP protocol may contribute to continued ischemic stroke occurrence. In the "Post-STOP" study, we sought to assess the impact of the STOP protocol on the incidence of ischemic stroke in a multicenter cohort of former STOP and/or STOP 2 trial participants. A central team abstracted data for 2851 (74%) of the 3835 children who took part in STOP and/or STOP 2. Data included TCD and neuroimaging results, treatment, laboratory data, and detailed clinical information pertaining to the stroke. Two stroke neurologists independently confirmed each stroke using pre-specified imaging and clinical criteria and came to consensus. Among the 2808 patients who were stroke-free at the start of Post-STOP with available follow-up, the incidence of first ischemic stroke was 0.24 per 100 patient-years (95% CI, 0.18, 0.31), with a mean (SD) duration of follow-up of 9.1 (3.4) [median 10.3, range (0-15.4)] years. Most (63%) strokes occurred in patients in whom the STOP protocol had not been properly implemented, either failure to screen appropriately with TCD (38%) or failure to transfuse adequately patients with abnormal TCD (25%). This study shows that substantial opportunities for ischemic stroke prevention remain by more complete implementation of the STOP Protocol.

S855 TCD IMPLEMENTATION RATES AND RESULTS IN THE MODERN ERA OF SICKLE CELL ANEMIA: RESULTS FROM THE DISPLACE STUDY

Background:Stroke is one of the most devastating complications of sickle cell anemia (SCA). The STOP (Stroke Prevention Trial in Sickle Cell Anemia) protocol was adopted in 2014 by the National Heart Lung and Blood Institute (NHLBI) guidelines for stroke‐risk screening using transcranial Doppler ultrasound (TCD) and prevention with chronic red cell transfusion therapy (CRCT) 1. Despite high‐level evidence supporting the use of TCD screening (and CRCT initiation) in stroke prevention2,3, wide scale implementation has not been achieved 4.Aims:The DISPLACE (Dissemination and Implementation Looking at the Care Environment) project is a multicenter, NHLBI‐funded study whose primary aim is to identify barriers to implementation of the STOP protocol and test novel methods for improving outcomes. DISPLACE is a 3‐part study: retrospective assessment of current practice, qualitative review of barriers and facilitators to screening and a cluster‐randomized intervention project using implementation science to improve TCD screening and CRCT implementation. We are reporting on part 1 of this project evaluating implementation rates of TCD screening and TCD outcomes (abnormal and conditional) in a large contemporary cohort.Methods:DISPLACE is a large multi‐site study consortium of 28 centers across the United States representing a range of characteristics: region (urban vs rural), size, and institution type (academic vs community). Each site performed a rigorous retrospective chart review of children with SCA aged 2–16 years from 2012–2016. To be eligible for inclusion, children had to have been seen at their institution at least 2x/calendar year (for 1 year) and have confirmation of SCA. A custom electronic data capture (EDC) system facilitated entry of de‐identified data including demographics, TCD and MRI results, medications, transfusions, and laboratory values. The primary study outcome is to assess implementation of TCD screening (per center). TCD screening rates were calculated per center (TCD/child/year/center). TCD results were recorded in the EDC as normal, conditional or abnormal. Stroke status was also recorded as well as presence or absence of CRCT. Data included missed TCD appointments and medical decisions based on TCD results.Results:The study included 28 centers. In total, 5223 individuals with SCA (50.2% male, 93.7% HbSS) are included in the database (5187 of those eligible in the study period). This is the largest cohort of children with SCA ever studied. TCD screening rates varied widely among institutions ranging from 30–75.2% (mean 48.4%, median 47%). Of the total in the database, 3718 patients had a TCD during the study period (71.7%). Of those patients who had a TCD, 138 (3.7%) had an ABNORMAL TCD per STOP guidelines which is notably lower than the STOP study with a rate of abnormal TCD of 9.7% at study entry. Characteristics of patients with abnormal TCD (vs. those without) are forthcoming.Summary/Conclusion:Despite the benefit of TCD screening in children with SCA, guideline‐based implementation remains poor. The range of barriers to screening will help investigators optimize the intervention protocol to enhance TCD implementation. Notably, there are fewer children with abnormal screening rates in the modern era which may represent partial penetration of the STOP Protocol from prior screening and/or effect of disease‐modifying therapy. Data analysis is in process to further qualify these findings.

S856 ALTERATION OF IRON HOMEOSTASIS IN A MOUSE MODEL OF LIVER-STAGE PLASMODIUM INFECTION

Background: Stroke is one of the most devastating complications of sickle cell anemia (SCA). The STOP (Stroke Prevention Trial in Sickle Cell Anemia) protocol was adopted in 2014 by the National Heart Lung and Blood Institute (NHLBI) guidelines for stroke-risk screening using transcranial Doppler ultrasound (TCD) and prevention with chronic red cell transfusion therapy (CRCT) 1. Despite high-level evidence supporting the use of TCD screening (and CRCT initiation) in stroke prevention2,3, wide scale implementation has not been achieved 4. Aims: The DISPLACE (Dissemination and Implementation Looking at the Care Environment) project is a multicenter, NHLBI-funded study whose primary aim is to identify barriers to implementation of the STOP protocol and test novel methods for improving outcomes. DISPLACE is a 3-part study: retrospective assessment of current practice, qualitative review of barriers and facilitators to screening and a cluster-randomized intervention project using implementation science to improve TCD screening and CRCT implementation. We are reporting on part 1 of this project evaluating implementation rates of TCD screening and TCD outcomes (abnormal and conditional) in a large contemporary cohort. Methods: DISPLACE is a large multi-site study consortium of 28 centers across the United States representing a range of characteristics: region (urban vs rural), size, and institution type (academic vs community). Each site performed a rigorous retrospective chart review of children with SCA aged 2–16 years from 2012–2016. To be eligible for inclusion, children had to have been seen at their institution at least 2x/calendar year (for 1 year) and have confirmation of SCA. A custom electronic data capture (EDC) system facilitated entry of de-identified data including demographics, TCD and MRI results, medications, transfusions, and laboratory values. The primary study outcome is to assess implementation of TCD screening (per center). TCD screening rates were calculated per center (TCD/child/year/center). TCD results were recorded in the EDC as normal, conditional or abnormal. Stroke status was also recorded as well as presence or absence of CRCT. Data included missed TCD appointments and medical decisions based on TCD results. Results: The study included 28 centers. In total, 5223 individuals with SCA (50.2% male, 93.7% HbSS) are included in the database (5187 of those eligible in the study period). This is the largest cohort of children with SCA ever studied. TCD screening rates varied widely among institutions ranging from 30–75.2% (mean 48.4%, median 47%). Of the total in the database, 3718 patients had a TCD during the study period (71.7%). Of those patients who had a TCD, 138 (3.7%) had an ABNORMAL TCD per STOP guidelines which is notably lower than the STOP study with a rate of abnormal TCD of 9.7% at study entry. Characteristics of patients with abnormal TCD (vs. those without) are forthcoming. Summary/Conclusion: Despite the benefit of TCD screening in children with SCA, guideline-based implementation remains poor. The range of barriers to screening will help investigators optimize the intervention protocol to enhance TCD implementation. Notably, there are fewer children with abnormal screening rates in the modern era which may represent partial penetration of the STOP Protocol from prior screening and/or effect of disease-modifying therapy. Data analysis is in process to further qualify these findings.

Relationship between Hemolytic Index Early in Life with Development of Abnormal Transcranial Doppler Velocities in Pediatric Patients with Sickle Cell Anemia

Introduction: Sickle cell disease is a complex disease process highlighted by a high phenotypic variability associated with a myriad of acute and chronic complications. Cerebrovascular disease is a serious complication in SCD associated with a high degree of morbidity and mortality. The utility of transcranial doppler ultrasound (TCD) to measure velocity within major arteries of the brain has been validated as a way to predict those at increased risk for stroke. Unfortunately, despite the availability of TCD, individuals may develop stroke and/or silent stroke prior to obtaining an abnormal study. Hemolysis via a hemolytic index variable has been shown to be associated with other complications associated with SCD. This study aimed to evaluate an association between a hemolytic index variable obtained in the first two years of life and development of abnormal or conditional TCD velocities later in childhood in patients with sickle cell anemia (SCA) with thoughts this may provide an earlier tool to determine those who may be at increased risk for stroke prior to either obtaining a TCD or developing an abnormal TCD.Methods: This study was a single-center, retrospective chart review of patients with SCA receiving their disease related care at our center over a 17 year period. Laboratory values, including lactate dehydrogenase (LDH), aspartate aminotransferase (AST), total bilirubin (TB), absolute reticulocyte count (ARC), and hemoglobin (HB), obtained in the first two years of life were extracted; these values were utilized to calculate a hemolytic index (HI) via principle component analysis to determine if a relationship existed between HI and development of conditional or abnormal TCD. All TCD results obtained from 2-14 years of age were also extracted from the patient's record. Cox proportional hazards models were then used to determine if the hemolytic index was a risk factor for abnormal or conditional TCD results.Results: A total of 193 patients with SCA between ages 2 - 21 years were reviewed with 109 included in the analysis. Laboratory values were averaged from included patients, then principle component analysis was used to find a linear combination of LDH, AST, TB and ARC to calculate a HI. The HI accounted for 49% of the total variation and had a correlation of 0.58 with mean LDH, 0.38 with mean AST, 0.46 with mean TB and 0.56 with mean ARC. Cox regression hazards model utilizing HI revealed a hazard ratio of 1.33 (95% CI 1.04‐1.70, p = 0.025) for developing a conditional or abnormal TCD velocity.HB was then included along with the other four laboratory values for principle component analysis in creation of a hemoglobin HI (HHI); in this case, the index accounts for 44% of the total variance and it has a correlation of 0.52 with mean LDH, 0.33 with mean AST, 0.38 with mean TB, 0.55 with mean ARC and ‐0.42 with mean HB. Cox regression hazards model utilizing HHI revealed a hazard ratio of 1.31 (95% CI 1.04‐1.66, p = 0.024).Conclusions: This retrospective study noted an increased risk for development of an abnormal or conditional TCD with an increased HI. The addition of hemoglobin to the HI to form HHI showed an elevated risk for abnormal or conditional TCD to the same degree as HI itself. These results could offer an additional tool in the evaluation of the pediatric SCA population, although these results would benefit from a prospective look. Further look into a possible association between HI and other SCD related complications such as stroke and acute chest syndrome could provide further information for the treating team for the overall management of this complex disease. [Display omitted] DisclosuresWoods:Global Blood Therapeutics: Research Funding; Pfizer: Research Funding; Guidepoint: Honoraria; Putman: Honoraria; Children's Mercy Hospital: Employment, Membership on an entity's Board of Directors or advisory committees.

Results from the Displace Consortium: Practice Patterns on the Use of Transcranial Doppler Screening for Risk of Stroke in Children with Sickle Cell Anemia

Abstract Introduction: Stroke is one of the most devastating complications of sickle cell anemia (SCA). The STOP (Stroke Prevention Trial in Sickle Cell Anemia) protocol has been adopted by National Heart Lung and Blood Institute (NHLBI) as the guideline for stroke screening using transcranial Doppler ultrasound (TCD) and prevention with chronic red cell transfusion therapy (CRCT). Evidence from the STOP I/II studies indicates the protocol is highly effective, yet wide scale implementation has not been achieved. The DISPLACE (Dissemination and Implementation Looking at the Care Environment) project is a multicenter, NHLBI funded consortium of 28 sites across the United States whose purpose is to identify barriers to the implementation of the STOP protocol and test novel methods for overcoming barriers. The purpose of this study was to use data on practice patterns to evaluate current measurement and practice standards at DISPLACE consortia sites. This abstract presents reported TCD screening and CRCT practices. Methods: A practice patterns survey was sent to the principal investigator (PI) for each DISPLACE site via RedCap ©. PIs were hematology/oncology specialty care providers for children with SCA. Sites represent urban and rural regions, large and small academic institutions, and community-based institutions. The survey was developed by the study investigators; questions were predominantly in a multiple-choice format. Items pertaining to TCD screening included: screening technique (including type of TCD); screening frequency; follow-up for abnormal, conditional, and inadequate results; standard value ranges. Results: All 28 PIs completed the survey. About half of the respondents were female (53.5%). Most identified as White (77.8%), followed by Asian (11.1%) and Black or African American (7.4%). Two identified as Hispanic or Latino (7.4%). Slightly more sites reported using standard TCD (57.1%) versus imaging TCD (TCDi) (42.9%). To calculate the time-averaged mean of the maximum (TAMM) velocities and characterize TCD results, nearly all sites use the middle cerebral artery (96.4%); a majority also use the anterior cerebral artery and/or the terminal internal cerebral artery or distal internal cerebral artery (71.4%). Fewer sites use the posterior cerebral artery (35.7%) or the basilar artery (14.3%). In 7.1% of sites, the radiologist determines which vessels to use during the exam. TCD screening is ordered for children with SCA annually in 92.9% of sites and every 6 months in 7.1% of sites. When TCD screening indicates abnormal TAMM velocities, 85.7% of sites initiate CRCT, 7.1% initiate hydroxyurea (HU) therapy, and 3.6% initiate both HU and CRCT. For additional evaluation, an MRI/MRA is obtained at 64.3% of sites. For high conditional results, the most common action is to initiate HU (67.9%). Other responses include obtaining an MRI/MRA (46.4%) and/or repeating the TCD in 2-4 weeks (25.0%), 6-8 weeks (35.7%), or 12-16 weeks (7.1%). Results deemed inadequate led to repeating the TCD in 2-12 weeks (57.1%) or in one year (3.6%), obtaining an MRI/MRA (57.1%), beginning HU therapy (7.1%), or no repeat TCD or change in management (3.6%). Actions for low conditional results include repeating the TCD (71.4%), obtaining an MRI/MRA (32.3%), and/or initiating HU therapy (57.1%). Surprisingly, sites use different TAMM ranges to characterize the normal/abnormal findings (Table 1). Conclusions: Nearly all DISPLACE sites order TCD screening annually, as recommended in the guidelines, with some ordering screening more frequently. A few sites did not report initiation of CRCT per STOP protocol for abnormal TCD results; however, over half of the sites reported following up with an MRI/MRA, which may suggest evaluating for vasculopathy prior to CRCT. Some sites reported beginning HU therapy for abnormal results; this may reflect consideration of patients for whom CRCT is not possible, but data were not collected for confirmation. Interestingly, results suggest a reliance on MRI/MRA since sites commonly reported ordering neuroradiology studies for abnormal, conditional, and inadequate TCD results. This may suggest an unclear pathway for children with borderline TCD results, and an area for future study. While reported value ranges closely approximated those in the STOP protocol, results indicate sites conducting screening with TCDi may use more conservative values than the validated protocol. Disclosures Phillips: NHLBI: Research Funding. Mueller:NHLBI: Research Funding. Schlenz:NHLBI: Research Funding. Melvin:NHLBI: Research Funding. Adams:NHLBI: Research Funding. Kanter:AstraZeneca: Membership on an entity's Board of Directors or advisory committees; bluebird bio: Membership on an entity's Board of Directors or advisory committees, Research Funding; Global Blood Therapeutics: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sancilio: Research Funding; NHLBI: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Apopharma: Research Funding; ASH: Membership on an entity's Board of Directors or advisory committees.

Evaluation of von Willebrand Factor and Factor VIII Levels in Sickle Cell Disease Children With Abnormal Transcranial Doppler Ultrasound Scan in Lagos University Teaching Hospital

Evaluation of von Willebrand Factor and Factor VIII Levels in Sickle Cell Disease Children With Abnormal Transcranial Doppler Ultrasound Scan in Lagos University Teaching Hospital

Haemoglobin oxygen saturation, leucocyte count and lactate dehydrogenase are predictors of elevated cerebral blood flow velocity in Nigerian children with sickle cell anaemia

Background: Transcranial Doppler ultrasound (TCD) scan, which measures blood flow velocity through the time-averaged mean of maximum velocities (TAMMVs) in the internal carotid arteries and middle cerebral arteries, is a useful screening tool for predicting stroke risk in children with sickle cell anaemia (SCA).Aim: To investigate which clinical and laboratory indices predict abnormal TCD velocity in children with SCA.Methods: Fifty-four SCA patients with normal TCD (TAMMV < 170 cm/s), classified as negative TCD (NTCD), and 93 patients with conditional and abnormal TCD velocities (TAMMV ≥ 170 cm/s) classified as positive TCD were recruited. The haemoglobin oxygen saturation, haematological variables, nitric oxide metabolites and lactate dehydrogenase activity of the patients were analysed.Results: The mean (SD) age was 7.16 (3.84) years (range 2–16). The median SpO2 of the patients in the positive TCD group was significantly lower than that of the negative TCD group (p = 0.002). Multivariate logistic regression analysis indicated that the MCV [odds ratio (OR) 1.12, 95% confidence interval (CI) 1.04–1.22, p = 0.01)], MCH (OR 1.34, 95% CI 1.02–1.77, p = 0.04), leucocyte count (OR 1.26, 95% CI 1.07–1.49, p = 0.01) and lactate dehydrogenase (LDH) level (OR 1.00, 95% CI 1.00–1.01, p = 0.01) were independent predictors of high cerebral blood flow velocities.Conclusions: These clinical and laboratory indices are characteristic of chronic hypoxia and severe anaemia and are predictors of abnormal cerebral blood flow velocity. They can be used to predict stroke risk in children with SCA when access to TCD screening is limited.

Impact of TCD Screening Protocol on the Incidence of Hemorrhagic Stroke in Children and Young Adults with Sickle Cell Disease

Background: Primary hemorrhagic stroke is a rare complication of sickle cell disease (SCD) that usually occurs in adults. The Stroke Prevention Trial in Sickle Cell Anemia (STOP) and Optimizing Primary Stroke Prevention in Sickle Cell Anemia (STOP 2) established routine transcranial Doppler ultrasound (TCD) screening with indefinite chronic red cell transfusions (CRCT) for patients with abnormal TCD as standard of care. Despite a notable improvement in the incidence of infarctive stroke in children with SCD after the introduction of TCD screening protocols, it is unclear how this protocol will affect the rate of hemorrhagic stroke. Presumably, early TCD screening and subsequent initiation of CRCT in high risk patients will prevent the progression of cerebral vasculopathy, which should decrease the risk of hemorrhagic stroke; however this has not been proven. Using the large multicenter cohort of children who participated in STOP and/or STOP 2 trials, we sought to assess whether the rate of hemorrhagic stroke was impacted by the use of TCD screening and/or CRCT.Subjects and Methods: Between 1995 and 2005, STOP and STOP 2 (STOP/2) were conducted at 26 sites in the US and Canada. These studies included 3835 children, ages 2 to 16 y with SCD type SS or S-beta-0-thalassemia. Participation in STOP/2 required at least a single screening TCD for randomization. Patients on STOP 2 also had an observational arm for children started on CRCT who had an abnormal TCD. The Post-STOP study was designed to follow-up the outcomes of children who participated in one or both of trials. For all participants the date of their last encounter in STOP/2 was defined as the start of their Post-STOP period. 19 of the 26 original study sites participated in Post-STOP, contributing a total of 3539 (92%) of the STOP/2 subjects. After exit from STOP/2, these children received TCD screening and treatment according to local practices. Data abstractors visited each clinical site and obtained retrospective data from STOP/2 study exit to 2012-2014 including follow-up TCD and brain imaging results, clinical information, and laboratory results. Two separate neurologists, blinded to STOP/2 status and prior TCD and neuroimaging results adjudicated all suspected strokes.Results: Follow-up data were available for 2850 of the 3539 subjects (81%). Twelve children who had a stroke during the STOP study period were further excluded from this analysis resulting 2838 subjects. The mean age at the start of Post-STOP was 10.5 years and mean duration of follow-up after exiting STOP/2 until time of last medical encounter was 9.1 years. A total of 31 patients had a primary hemorrhagic stroke during the Post-STOP observation period (incidence 0.12 per 100 pt years). The mean age at time of stroke was 16.2+5.6 (median 15.3 range (4.8-30.2) years of age. Of those 31 patients, only 52% had a TCD during Post-STOP prior to the event. Seven of those children who underwent screening had documentation of an abnormal TCD prior to the event (5 during STOP era and/or 3 Post-STOP). However, only 1/7 patients (14%) were documented on CRCT at the time of the stroke (4 patients were receiving HU and 2 patients had unknown treatment).Discussion: Although less common than infarctive stroke, patients with SCD are at increased risk for hemorrhagic stroke. There is an increased risk of mortality for patients who suffer from hemorrhagic stroke (up to 26% in some reports in the 2 weeks after the event). It is unclear if TCD screening and subsequent initiation of CRCT will impact the rate of hemorrhagic stroke in the long term. In our results, a similar incidence of primary hemorrhagic stroke was noted although the patients were overall younger than previously reported (16.5+/- 5.5 years versus 20-29 years in Cooperative Study of Sickle Cell Disease). Many patients who had a hemorrhagic stroke (48%) had not undergone TCD screening during the Post-Stop period. Additionally, although a safe stopping point for CRCT has not been established in patients who have had an abnormal TCD, only 1 patient was documented on CRCT at the time of the event (14%). Thus, it is unclear at this time whether TCD screening and subsequent, lifelong continuation of CRCT could have prevented these other events. Clearly, these results demonstrate that improved implementation of STOP protocol is needed as well as further evaluation of the impact of this protocol on the incidence of hemorrhagic stroke. DisclosuresNo relevant conflicts of interest to declare.

Ischemic Stroke in Children and Young Adults with Sickle Cell Disease (SCD) in the Post-STOP Era

Background: The Stroke Prevention Trial in Sickle Cell Anemia (STOP) and Optimizing Primary Stroke Prevention in Sickle Cell Anemia (STOP 2) established routine transcranial Doppler ultrasound (TCD) screening with indefinite chronic red cell transfusions (CRCT) for children with abnormal TCD as standard of care. To identify children at high-risk of stroke, annual TCD screening is recommended from ages 2 to 16 years, with more frequent monitoring if the result is not normal. A reduction in stroke incidence in children with SCD has been reported in several clinical series and analyses utilizing large hospital databases when comparing rates before and after the publication of the STOP study in 1998. We sought to determine the rate of first ischemic stroke in a multicenter cohort of children who had previously participated in the STOP and/or STOP 2 trials and to determine whether these strokes were screening or treatment failures.Subjects and Methods: Between 1995 and 2005, STOP and STOP 2 (STOP/2) were conducted at 26 sites in the US and Canada. These studies included 3,835 children, ages 2 to 16 y with SCD type SS or S-beta-0-thalassemia. Participation in STOP/2 ranged from a single screening TCD to randomization. STOP 2 also had an observational arm for children on CRCT for abnormal TCD whose TCD had not reverted to normal. The Post-STOP study was designed to follow-up the outcomes of children who participated in one or both trials. 19 of the 26 original study sites participated in Post-STOP, contributing a total of 3,539 (92%) of the STOP/2 subjects. After exit from STOP/2, these children received TCD screening and treatment according to local practices. Data abstractors visited each clinical site and obtained retrospective data from STOP/2 study exit to 2012-2014 (depending on site) including follow-up TCD and brain imaging results, clinical information, and laboratory results. Two vascular neurologists, blinded to STOP/2 status and prior TCD and neuroimaging results, reviewed source records to confirm all ischemic strokes, defined as a symptomatic cerebral infarction; discordant opinions were resolved through discussion. For the first Post-STOP ischemic stroke, prior TCD result and treatment history subsequently were analyzed.Results: Of the 3,539 subjects, follow-up data were available for 2,850 (81%). Twelve children who had a stroke during STOP or STOP2 were excluded from these analyses resulting in data on 2,838 subjects. The mean age at the start of Post-STOP was 10.5 y and mean duration of follow-up after exiting STOP/2 was 9.1 y. A total of 69 first ischemic strokes occurred in the Post-STOP observation period (incidence 0.27 per 100 pt years). The mean age at time of stroke was 14.4±6.2 (median 13.8, range 3.5-28.9) y. Twenty-five of the 69 patients (36%) had documented abnormal TCD (STOP/2 or Post-STOP) prior to the stroke; 15 (60%) were receiving CRCT and 9 (36%) were not (treatment data not available for 1 subject). Among the 44 subjects without documented abnormal TCD, 29 (66%) had not had TCD re-screen in the Post-STOP period prior to the event; 7 of these 29 (24%) were 16 y or older at the start of Post-STOP, which is beyond the recommended screening age. Four of the 44 (9%) patients had inadequate TCD in Post-STOP (1 to 10.7 y prior to event). Six (14%) had normal TCD more than a year before the event (1.2 - 4 y); all but one of these children were younger than 16 y at the time of that TCD. Only 5 (11%) had a documented normal TCD less than 1 year prior to the event.Conclusions: In the Post-STOP era, the rate of first ischemic stroke was substantially lower than that reported in the Cooperative Study of Sickle Cell Disease, prior to implementation of TCD screening. Many (39%) of the Post-STOP ischemic strokes were associated with a failure to re-screen according to current guidelines, while only 11% occurred in children who had had recent low-risk TCD. Among those known to be at high risk prior to stroke, treatment refusal or inadequate treatment may have contributed. While TCD screening and treatment are effective at reducing ischemic stroke in clinical practice, significant gaps in screening and treatment, even at sites experienced in the STOP protocol, remain to be addressed. Closing these gaps should provide yet further reduction of ischemic stroke in SCD. DisclosuresNo relevant conflicts of interest to declare.