Voxelotor Use in Adults with Sickle Cell Disease in a
Real‐World
Setting
Abstract Background: Sickle cell disease (SCD) is among the most common, lethal and poorly recognized diseases globally. Over 300,000 children are born each year with SCA and most die by five years, primarily due to the lack of timely and accurate diagnosis. In high-resource countries, early identification of SCD through newborn screening (NBS) is routine and subsequent delivery of preventive measures and comprehensive care is highly effective in reducing morbidity and early mortality. In lower-resource settings, where the incidence of SCD is much higher, NBS is limited to only a few pilot programs. Despite the proven efficacy of NBS, large-scale implementation remains infeasible in many sub-Saharan countries due to inadequate financial, laboratory, and technical resources. In the pilot NBS program in Angola, only 56% of infants with SCD were able to be contacted to relay results due to delays in traditional laboratory diagnostic methods, lack of traditional mailing system or primary care providers, and inconsistent telephone numbers. The development and deployment of low-cost, rapid, user-friendly, and accurate diagnostic testing for SCD is imperative. There are two promising point-of-care (POC) tests (Sickle SCAN and HemoTypeSC) that may allow for a simplified approach to newborn screening for SCD. There have been few real-world studies that compare these tests head to head, particularly in the setting of NBS, where accurate diagnosis amidst high levels of fetal hemoglobin is critical. We performed a study at maternity centers and immunization centers in Luanda, Angola to evaluate the real-world accuracy of these tests. Methods: The study was a prospective evaluation of two rapid, POC tests (Sickle SCANÔ or HemoTypeSCÔ) ain Luanda, Angola, with laboratory confirmation using a dried blood spot (DBS) by isoelectric focusing (IEF), defined as the gold standard. To evaluate the real-world feasibility and accuracy, with the guidance of the Angolan Ministry of Health, we selected 10 sites, including both birth hospitals and vaccination sites, to screen infants < 6 months of age. Due to the complexity of performing more than one POC at once, we focused on one POC test at a time and planned to test 100 infants with each test at each site, for a total of 2,000 infants tested overall. The study was designed to mimic a real-world setting with all POC testing performed and interpreted by local healthcare staff (nurses, students, and laboratory technicians) with basic instructions as to the use of each test. Results: Blood samples were collected from 2,000 infants from age 0 to 6 months of age, including 1,000 with Sickle SCAN and 1,000 with HemoTypeSC. 42 HemoTypeSC samples (4.2%) and 6 Sickle SCAN results (0.6%) were not included in the final analysis, as results were not interpreted in the recommended time frame (5 minutes for Sickle SCAN an 10 minutes for HemoTypeSC). Consistent with prior studies in Angola, the burden of sickle cell trait (AS, 21.9%) and sickle cell anemia (HbSS, 1.7%) was high. 63% of the tests were performed in maternity wards at the time/day of birth and 37% were performed in immunization centers through the first 6 months of life. The HemoTypeSCÔ took an average of 15 minutes to obtain a result, was repeated 68 times (6.8%) due to invalid results, and was read incorrectly 4 times (0.4%). The SickleScanÔ took an average of 7 minutes to run, was repeated 2 times (0.2%) due to invalid results, and read incorrectly 11 times (1.1%). All results were compared to the gold standard IEF and both tests correlated perfectly (100%) with the IEF results, excluding 12 samples that had inconclusive IEF results. Conclusions: This study demonstrates the feasibility and accuracy of both HemoTypeSC and Sickle SCAN for diagnosing SCD in newborns in a limited-resource setting of Luanda, Angola. Given the complexities of testing in the newborn period at busy maternity hospitals, it appears that testing at immunization centers may be a more practical solution to early infant diagnosis programs for SCD. While both HemoTypeSC and Sickle SCAN were accurate, Sickle SCAN was preferred by local staff likely due to the shorter time to interpretation and reduced need for repeating the test. Further implementation studies are needed, including careful analysis of end-user cost, to determine the appropriate strategy for these POC tests in low-resource setting of sub-Saharan Africa. Disclosures No relevant conflicts of interest to declare.
Background: Sickle Cell Disease (SCD) is a severe, potentially life threatening hereditary hemoglobin disorder requiring multidisciplinary care including screening, prevention, health education and management of acute and chronic complications. [ME Houwing et al, Blood Rev 2019] Although it affects millions of people throughout the world mainly individuals of African descent, Mediterranean (Caucasian) and Asiatic population, global migration from regions where the disease is endemic are changing its geographical distribution with a significant impact on patient survival, quality of life and costs for health systems requiring new treatment and preventive approaches. Data on epidemiological and clinical profiles of SCD have deeply changed also in Italy, a country with a high prevalence of hemoglobinopathies and where SCD is already present in the native population, due to an increasing number of immigrants from countries with high disease prevalence. Currently, approximately 2,000 SCD patients live in Italy. The creation of an Italian National Registry of Thalassemia and Hemoglobinopathies - was approved in 2017 thanks to a strong joint initiative of the Italian Society of Thalassemias and Hemoglobinopathies (SITE) and national patients associations. However the Registry is not yet completed, thus, the information currently available is very limited. [G Russo et al, Orphanet J Rare Dis. 2019] The Italian National Health Service is organized in Regions and Local Health Units (LHU). Each LHU reimburses health providers (eg, public and private hospital, general practitioners, outpatient services providers) for health assistance provided to citizens referring to the LHU, and uses specific databases to track the health assistance provided containing useful data to describe the type of assistance (eg, patient beneficiary, date of assistance) and to calculate the related charge. The main purpose of GREATalyS trial (CSEG101AIT01) is to collect data on SCD which may be representative of the national picture to better understand the burden of illness in terms of patient population, key disease features and resources consumption in Italy. Methods: Observational retrospective analyses will be carried out by integrating administrative databases for healthcare resources consumption (pharmaceuticals database, hospitalizations database, diagnostic tests and specialist visits database) from a sample of Italian Regions and LHUs, geographically distributed across the National territory (balanced between regions and number of covered residents). A representative sample of the whole national landscape through the involvement of approximately 11 LHUs and Regions will allow capture of approximately 23 million covered residents, representing about 38% of the entire Italian population. Patient Socio-Demographic characteristics (age, gender), all hospitalizations (SCD related and not related), previous SCD treatment type, co-morbidity profiles, patient treatment patterns, resources use and health services cost will be collected and analyzed. Anonymized patient data will be extracted into the Hospitalization database searching the relevant International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM codes). All analyses will be performed by STATA SE, version 12.0. The Local Ethics Committee of each participating Region/LHU has been notified about the study. Objectives: Composite objectives will collect both epidemiological and burden of illness data. Primary study objective is to estimate SCD prevalence and incidence rate from January 2010 to December 2018. Key secondary objectives include description of demographic and clinical characteristics, therapeutic pathways, health care resource use and direct costs (derived from health care resource utilization in term of drug treatments, diagnostic tests, specialist visits and hospitalizations) for patients affected by SCD. Conclusions: GREATalyS is to our knowledge the first SCD real world evidence study in Italy leveraging National Health System administrative databases to collect epidemiological and burden of illness data, and represents a useful health assessment model to better understand the evolving scenario in Italy, a country where SCD is becoming an emerging health problem. Figure Disclosures Castiglioni: Novartis Farma SpA: Employment. Condorelli:Novartis Farma SpA: Employment. Amore:Novartis Farma SpA: Employment. Perrone:CliCon srl: Employment. Alessandrini:CliCon srl: Employment. Veronesi:CliCon srl: Employment. Degli Esposti:CliCon srl: Employment. Premoli:Novartis Farma SpA: Employment. Fiocchi:Novartis Farma SpA: Employment.
Abstract Background: Hydroxyurea (HU) and chronic transfusion therapy (CTT) are the only disease modifying therapies (DMTs) currently available as standard of care in the UK and Italy for patients with sickle cell disease (SCD), with hematopoietic stem cell transplant (HSCT) available to a small fraction of patients. Few registries capture long-term follow up of real-world outcomes among patients with SCD and there is a need for natural history studies demonstrating morbidity and mortality under existing standard of care. The East London Newborn Sickle Cohort Study (ELNSCS) at the Royal London Hospital and the Sickle Cell Disease Cohort (SCDC) at the University of Padova (UNIPD) collect biomarker and clinical data on patients followed comprehensively at two expert referral centers and provide an opportunity to understand SCD real-world outcomes. Here, we report severe acute complications under standard of care during years when HU and CTT were widely available and accepted. Methods: Inclusion of patients in the ELNSCS required being born in a designated region in London, diagnosed by newborn screening between 1983-2018 and, for this analysis, followed during 2015-2018. Inclusion in the SCDC required being followed, for this analysis, at the UNIPD during 2016-2019. Analyses were restricted to patients with β Sβ S, β Sβ 0, and, for ELNSCS, β Sβ +. Data were entered into clinical databases at each site and subsequently validated against institutional records. Severe vaso-occlusive events (VOEs) were defined as events requiring admission (inpatient, ED, or hematology day unit) for acute chest syndrome (ACS), acute painful crisis, acute hepatic/splenic sequestration, acute ischaemic stroke, dactylitis and priapism. Statistical analysis was aligned between both sites. Patients were categorized into three mutually exclusive treatment groups (HU, CTT, no treatment) according to treatment during study period. Results: One hundred seventy-two patients in the ELNSCS and 62 patients at UNIPD met study inclusion criteria in the four-year analysis period. HbSS genotype accounted for 161 (93.6%) of ELNSCS cohort and 58 (93.5%) of UNIPD cohort. Median age at study entry was 11.6 (range 0.2 - 31.4) years in the ELNSCS and 7.66 (range 0.12 - 19.96) years at UNIPD. Median age differed across treatment groups; HU group tended to be younger, while CTT group tended to be older. According to institutional standards of care, 47 (27.3%) patients from the ELNSCS and 50 (80.6%) from UNIPD received HU, 53 (30.8%) from the ELNSCS and 8 (12.9%) from UNIPD received CTT, and 72 (41.9%) from the ELNSCS and 4 (6.5%) from UNIPD received no treatment during the four year study period. Differences in treatment allocation reflect slightly different patient populations and approaches to care at the two centers. Severe VOEs persist among patients in all three treatment groups at both sites. Of those receiving HU, 83.0% from the ELNSCS and 68.0% at UNIPD had ≥1 severe VOE, including 21.3% from the ELNSCS and 44.0% at UNIPD experiencing ≥1 ACS event. The rate of severe VOEs in the HU group was 0.75 (range 0 - 39.5) per patient year from the ELNSCS and 0.49 (range 0 - 3.00) per patient year from UNIPD. HU dosing and adherence will be explored using data collected on hematologic parameters. In the ELNSCS, of those receiving CTT, 60.4% experienced ≥1 severe VOE (20.8% had ≥1 ACS event); of those receiving no therapy, 56.9% experienced ≥1 severe VOE (11.1% had ≥1 ACS event). At UNIPD, severe VOEs were observed in 62.5% of the CTT group and 50% of the no treatment group, though sample sizes were very small. C onclusions: Despite receiving expert care in accordance with local and international guidelines at two large academic centers, a significant sub-group of patients continue to experience severe VOEs. Results show that real-world usage of HU and CTT may not be optimized and, even if optimized, some patients may continue to experience severe acute complications including ACS. Both cohorts confirm that implementation of existing standard of care is insufficient to prevent significant morbidity in patients with SCD. Findings suggest the need to introduce DMT early in life to reduce and prevent acute complications and minimize disease progression. There is a persistent need for maximizing effective DMTs, as well as further developing curative therapies such as HSCT and gene therapy for both pediatric and adult patients. Figure 1 Figure 1. Disclosures Colombatti: Novartis: Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; BlueBirdBio: Membership on an entity's Board of Directors or advisory committees, Research Funding. Chawla: BlueBirdBio: Current Employment. Puri-Sharma: BlueBirdBio: Current Employment. Walls: BlueBirdBio: Current Employment. Kommera: BlueBirdBio: Current Employment. Telfer: Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Emmaus: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Addmedica: Membership on an entity's Board of Directors or advisory committees; ApoPharma: Membership on an entity's Board of Directors or advisory committees; Global Blood Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BlueBirdBio: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Terumo: Honoraria; Roche: Membership on an entity's Board of Directors or advisory committees.
Patients with sickle cell disease (SCD) are now routinely living into adulthood, but SCD has deleterious effects on multiple organ systems which can lead to increased complications from illness. SCD patients generally auto-splenectomize in childhood secondary to infarctions from their hemoglobinopathy, thus increasing their risk of infection with encapsulated organisms such as S. pneumoniae. Although there are data to demonstrate that vaccination has drastically decreased the incidence of invasive pneumococcal disease (i.e. bacteremia or meningitis) in children, the situation for adults is less clear. There are no data to guide the decision to use conjugated and/or polysaccharide pneumococcus vaccines in adults. In addition, there are few data available on the efficacy of pneumococcal vaccination on non-invasive disease such as pneumonia. Two landmark studies have demonstrated the efficacy of polysaccharide-based pneumococcal vaccines in the general adult population to be approximately 56%. However, there are data to suggest that immune responses in SCD patients may be impaired, and thus responses to vaccines may be suboptimal. Current sickle cell guidelines for pneumococcal vaccination, which are based on expert opinion, recommend one dose of Prevnar 13 (conjugated vaccine) followed by one dose of Pneumovax 23 (polysaccharide vaccine) with a booster of Pneumovax 23 at age 65. However, some clinicians choose to vaccinate every 5 years due to fear of waning immunity. There is a lack of data on which to base guidelines, and there are also no data nor any guidelines to help decide if patients needs additional boosters of vaccine. Besides the potential for suboptimal immune responses in sickle cell patients, the standard definition used to define a responder to pneumococcal vaccine may not translate to protection from disease in the real world. Most studies define a responder as having a protective titer to 50-70% of the serotypes tested. However, this definition has no consideration for the prevalence of serotypes causing disease in the community. Therefore it's possible to have a patient who responds to 50% of the serotypes in the assay and is considered immune, but if those serotypes are all uncommon, then the patient may still be at high risk for serious disease. Determining a better way to identify patients at risk for pneumococcal disease and optimizing vaccination strategies to prevent this disease would help to improve the lives of patients. We performed a retrospective study to investigate immunity to pneumococcus in adult patients with SCD. We used the electronic medical record and collected data on patient demographics, sickle cell genotype, dates of previous pneumococcal vaccination (both conjugated and polysaccharide vaccines), quantitative antibody levels to individual pneumococcus serotypes, as well as information on comorbidities. In our sample of n=28 patients with SCD and available antibody data, 68% met a commonly accepted definition of immunity, which we defined by having an antibody concentration ≥ 1 mcg/mL for at least 50% of any of the serotypes tested. Immunity was inversely correlated with time from last pneumococcal vaccination, and it did not matter whether the most recent vaccine was the conjugated or polysaccharide product (Fig 1a). We then sought to analyze the data with consideration for the prevalence of various serotypes based on epidemiologic data published in The Lancet Infectious Diseases15,301-309 (2015). Interestingly, only 21% of patients who met the traditional definition of being a vaccine responder had protective titers to all 3 of the most prevalent serotypes tested, and 10% of patients who would traditionally be characterized as vaccine responders did not have sufficient antibody production to any of the 3 most prevalent serotypes tested in the assay (Fig. 1b, left). Of the 9 patients who were categorized as vaccine nonresponders based on the traditional definition, one subject was actually immune to all 3 of the most common serotypes in the community (Fig 1b, right), suggesting that he may actually be well-covered for pneumococcus in the real world. This study raises concern about the definition of immunity following vaccination, and highlights the challenge to identify which patients are at risk for disease. Future studies should examine how immunity wanes post vaccination and how the lack of immunity to prevalent serotypes might lead to clinical disease. Disclosures Lanzkron: Pfizer: Research Funding; Global Blood Therapeutics: Research Funding; Ironwood: Research Funding; HRSA: Research Funding; NIH: Research Funding; PCORI: Research Funding.
Abstract Background: Vaso-occlusive crises (VOC) are the most common acute complication of sickle cell disease (SCD). Crizanlizumab, an anti-P-selectin monoclonal antibody, is an FDA-approved disease-modifying therapy (DMT) for SCD patients (pts) aged ≥16 yrs to reduce the frequency of VOC. To better understand its use and impact, the National Alliance for Sickle Cell Centers (NASCC) conducted a retrospective study of pts prescribed crizanlizumab from 11/2019-6/30/2021. NASCC is a non-profit organization formed to support SCD centers in delivering quality comprehensive care by setting and adopting specific standards and advocating for improved health outcomes in SCD. This study describes the largest real-world cohort of pts treated with crizanlizumab. Methods: This is a two-part study. Part 1 was to evaluate NASCC center crizanlizumab practice and to summarize data on insurance approval and the frequency of drug discontinuation. Part 2 includes pt level data to evaluate reasons for discontinuation and acute care utilization pre and post therapy. Acute care use includes day hospital/infusion, emergency department visits, and hospitalizations for VOC (excluding COVID-19). The index date for each pt is defined as the 1st crizanlizumab infusion date. Chart review (electronic health records) was used to identify all acute care visits 12 months pre-index and ≤12 months post index. Acute care data will be analyzed in aggregate. Evaluation of center-specific use of crizanlizumab, time to initial site level formulary approval and drug discontinuation were analyzed. Pt level data collection is ongoing to include sufficient time post index date. VOC characteristics will be summarized using medians, median differences (pre/post treatment), and 95% confidence intervals. Additional evaluation of effectiveness of crizanlizumab will include analysis based on number of doses received, pre-treatment VOC burden, concomitant hydroxyurea (HU) use and genotype. Results: Data includes pts prescribed crizanlizumab at 11 NASCC centers. Site- formulary approvals to use crizanlizumab varied from 12/2019-12/2020. As a result, the 1st pt to receive treatment at each site varied from 1/15/2020-1/20/2021. Mean time from site-level approval to first infusion was 77 days (range: 0-394). Over 50% of sites received insurance denials mainly due to "insufficient medical necessity" or "medication not covered by the prescription plan." Sites were able to successfully appeal denials for 71% of pts (Table 1). Treatment Delivery: Each site gives infusions over 30 minutes and the majority (64%) do not use pre-medication unless pts had reactions. Some sites use diphenhydramine/acetaminophen (3) or normal saline and ketorolac (1). All sites prescribe crizanlizumab to pts of all SCD genotypes. Pts Treated: 297 pts were prescribed crizanlizumab of whom 238 received ≥ 1 infusion. There was variation in number of pts/site (range 6-73, mean 21) due to time to site-level approval, insurance and pt population. Of these 238, 75 pts (32%) discontinued treatment (0-17 pts/site). Sites reported pts perceived lack of improvement or feeling their overall pain was increased, transportation issues and infusion related reactions (IRRs) characterized by pain as some of the reasons for discontinuation. Evaluation of real-world efficacy measured by changes in acute care utilization, including sub-analysis by genotype, pre-treatment VOC burden and concomitant HU use, are pending sample size dependent feasibility. Discussion: This is the first multi-center real-world analysis of crizanlizumab. Findings demonstrate some insurance barriers to therapy. The majority of pts who initiated crizanlizumab have remained on therapy; however, 1/3 of pts had lack of effect or barriers to care. Pt level data will include characteristics related to treatment failure or IRR. Improving the understanding of phenotype-specific response to novel therapies is essential in SCD. Conclusion: Post-approval therapies for rare diseases must undergo real-world evaluation to ensure study results translate to the community. NASCC uses defined criteria for multidisciplinary care for Alliance inclusion and findings reflect the use of DMT in such centers. This is the first NASCC study of DMT in SCD. Part 2 of the study will give early insights into the effectiveness of crizanlizumab; long term follow-up is needed for a full understanding of its utility in SCD. Figure 1 Figure 1. Disclosures Kanter: Fulcrum Therapeutics, Inc.: Consultancy; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Forma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees; Beam: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Graphite Bio: Consultancy; GuidePoint Global: Honoraria; Fulcrum Tx: Consultancy. Manwani: Novartis: Consultancy. Idowu: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Forma Therapeutics, Inc.: Research Funding; Ironwood: Research Funding. Treadwell: National Alliance of Sickle Cell Centers: Other: Early Evaluation of the Use of Crizanlizumab in Sickle Cell Disease. Clay: GBT: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria. Little: Hemex Health, Inc.: Patents & Royalties; Biochip Labs: Patents & Royalties. Desai: Global Blood Therapeutics: Honoraria, Research Funding; Novartis: Research Funding, Speakers Bureau; Pfizer: Other: Publication Fee, Research Funding; Forma: Consultancy; Foundation for Sickle Cell Research: Honoraria. Lanzkron: Shire: Research Funding; Pfizer: Current holder of individual stocks in a privately-held company; Bluebird Bio: Consultancy; Teva: Current holder of individual stocks in a privately-held company; Novo Nordisk: Consultancy; GBT: Research Funding; Imara: Research Funding; CSL Behring: Research Funding; Novartis: Research Funding.
Background Sickle cell disease (SCD) is a progressively debilitating monogenic disease characterized by unpredictable, acute, life-threatening episodes and chronic complications such as hemolytic anemia and end-organ damage. It presents with a range of severity resulting in significant morbidity, poor quality of life, and early mortality. Real-world data on treatments and clinical outcomes for patients (pts) with SCD are limited, particularly in the community clinical care setting. The objectives of this retrospective real-world study were to characterize clinical manifestations and management of pts with SCD treated at the Foundation for Sickle Cell Disease Research (FSCDR). Methods A retrospective longitudinal analysis of an electronic health records (EHR) database from the FSCDR, which captured laboratory testing, treatments, and records on outpatient, emergency, and inpatient visits, was conducted. All unique pts with SCD assigned a medical record number in the EHR (N=172) were considered. Data from external records were manually entered into the EHR to supplement the EHR database. To address limitations of a real-world database, medical records for all pts included were manually reviewed and validation was performed on 10% of the sample. Pt demographics, clinical characteristics, hydroxyurea (HU) treatment (as captured by prescriptions and usage notes), administration of red blood cell transfusions, vaso-occlusive crisis (VOC) events and acute chest syndrome (ACS) (based on physician assessment) were described. Annual VOC rates were summarized by dividing the number of events by the total follow-up duration in years. Results In total, 122 pts with SCD were included. Twenty-three pts were excluded as they were not actively seeking care and/or had no relevant clinical data from 01/01/15-07/19/19. Data for 27 pts <22 years of age were unavailable at time of analysis (results of this cohort will be included in the presentation). Among all pts, 76 (62.3%) were female and 118 (96.7%) were Black or African American. The mean age at time of analysis was 39.1 (standard deviation [SD] 12.3) years with 9 (7.4%) 22-24 year-olds, 67 (54.9%) 25-40 year-olds, 35 (28.7%) 41-55 year-olds, and 11 (9.0%) ≥ 56 year-olds. The most common genotypes were HbSS (77.0%) and HbSC (17.2%). Over a mean follow-up period of 2.9 (interquartile range: 2.0, 4.4) years, 27 (22.1%) pts were treated with HU and 66 (54.1%) pts received transfusions, of which 1 (1.5%) pt chronically received episodic transfusions (i.e., continuous monthly transfusions for ≥ 6 months). The mean total hemoglobin (Hb) was 8.3 (SD 1.7) for HbSS pts and 10.9 (SD 1.5) for HbSC pts. Among pts who never received HU or transfusions during follow-up, mean Hb was 9.4 (SD 1.7) for HbSS pts and 11.4 (SD 1.6) for HbSC pts. Among pts who ever received HU or transfusions, mean Hb was 7.7 (SD 1.3) for HbSS pts and 10.3 (SD 1.1) for HbSC pts. Eleven (9.0%) pts had ≥ 1 ACS whereas 97 (79.5%) pts had ≥ 1 VOC event. ACS and VOC events occurred mostly in pts 25-55 years of age (ACS: 9 [81.8%] pts aged 25-40 years and 2 [18.2%] pts aged 41-55 years; VOC: 54 [55.7%] pts aged 25-40 years and 29 [29.9%] pts aged 41-55 years). Annual rates of VOC are described in Figure 1. Conclusions This is one of the first studies to describe clinical characteristics and management of pts with SCD in a community practice setting. Higher Hb levels among pts who never vs ever received HU or transfusions during follow-up may be a reflection of who were selected for treatment and additional studies to take into account timing of treatment and Hb assessments and confounding factors need to be conducted. The study found high VOC rates particularly among pts aged ≤ 40 years. Lower VOC rates among older pts do not necessarily indicate less severe disease. One potential reason for lower VOC rates among older pts with SCD is that cumulative exposure to ischemia-related tissue injury and resulting end organ damage may decrease VOC-related pain over time. Further investigation to elucidate the rate of VOC decline observed in older pts is needed, including looking at underlying health and end organ damage. While limitations are inherent in real-world studies, these findings underlie the ability to and importance of studying SCD management and clinical outcomes in community care settings. This study highlights the clinical burden of SCD and possibly higher than expected unmet need in this community setting. Disclosures Bronté-Hall: bluebird bio: Research Funding. Huynh:bluebird bio: Research Funding. Puri-Sharma:bluebird bio: Employment. Chang:bluebird bio: Research Funding. Chawla:bluebird bio: Employment. Signorovitch:bluebird bio: Research Funding.
Abstract Background and purpose Sickle cell disease (SCD) is a collection of rare inherited blood disorders affecting approximately 100,000 people in the U.S. and 20–25 million people globally. Individuals with SCD experience recurrent episodes of severe and unpredictable pain that are caused by vaso-occlusive crises (VOCs), a hallmark of the disease. VOCs are the primary cause of hospitalization in SCD, result in missed workdays and school days, and decrease quality of life (QoL). Although VOCs cause significant burden in the lives of individuals with SCD, there is no synthesis on the frequency of VOCs in the real world. This systematic literature review sought to identify literature describing the frequency of VOCs experienced by individuals with SCD in real-world settings. Methods MEDLINE and 6 congresses were searched (date range: January 1, 2000 to June 30, 2020). Studies were reviewed independently by two researchers. Studies assessing frequency or prevalence of VOCs or VOC-related outcomes were included. Results Of 1438 studies identified in the search, 52 met pre-specified inclusion and exclusion criteria. Reported frequency of VOCs varied widely ranging from a mean or median of 0 VOCs/year to 18.2 VOCs/year. The proportion of patients experiencing ≥ 3 VOCs/year ranged from 4 to 67% and the proportion of patients experiencing ≥ 5 VOCs/year ranged from 18 to 59%. Measures of VOC severity were limited, with 13 studies considering frequency of complicated VOCs and only 1 study reporting duration of VOC episodes. Conclusions This is the first study to systematically assess published evidence pertaining to VOCs in real-world settings. Reported VOC frequency in real-world settings varied widely, with a majority of studies only considering VOCs managed in an inpatient or outpatient setting. Studies that considered VOCs managed at home reported a higher frequency of VOCs, suggesting that many studies may underestimate the frequency of VOCs. This systematic literature review (SLR) highlights the need for consistent reporting of (1) self-reported VOCs, including those managed at home, (2) definitions of VOCs, (3) complicated VOCs, and (4) duration of VOC episodes in literature.
