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Background: The coronavirus disease pandemic of 2019 (COVID-19) has been associated with coagulopathy and an increased rate of thrombosis in adults. Medical practitioners have been prompted to consider prophylactic anticoagulation in special populations diagnosed with COVID-19. Patients with sickle cell disease (SCD) are predisposed to a hypercoagulable state. Despite the concern for development of venous thromboembolism (VTE) in these patients, there are no standardized guidelines for routine thromboprophylaxis in either adults or children with SCD. Thus, VTE management options are often extrapolated from guidelines for the general population. Methods: A cross-sectional electronic survey was distributed to pediatric and adult hematology oncology practitioners through 7 SCD specific interest groups. Pediatric and adult practitioners were defined as those who medically manage patients 0-21 years of age and >21 years of age respectively. We examined responses to survey questions focused on routine thromboprophylaxis practices in children and adults with SCD prior to the pandemic and in patients with SCD admitted with COVID-19. Chi-square analyses or Fisher's exact tests for small samples were used to compare proportions as needed. Results: The survey was distributed to approximately 2,550 providers. Of 93 total responses, 14% (N=13) only treat patients >21yo; 38.7% (N=36) only treat patients 0-21yo and 47.3% (N=44) treat both. Nearly all adult practitioners (96.6%) would recommend pharmacologic prophylaxis, mechanical prophylaxis or both for hospitalized adults, but only 76% of pediatric treaters would recommend any prophylaxis (PPX) in hospitalized children (p21yo patients, 51% preferred to use both pharmacologic and non-pharmacologic PPX, 25% preferred pharmacologic alone, with just 5.3% preferring non-pharmacologic PPX only. Enoxaparin was the most frequently used anticoagulant among both pediatric and adult practitioners [78% vs 89% respectively] (Figure 2). Direct oral anticoagulants (DOACS) were infrequently recommended (3.8% for SCD children and 10.9% for adults); of these, rivaroxaban was used most often. The most common indication for starting thromboprophylaxis for both 0-21yo and >21yo patients was history of prior VTE [81% and 81% respectively], followed by hip replacement [57% and 75% respectively]. In patients admitted with COVID-19, prophylactic anticoagulation was recommended for adults by 94% of treaters. There was a significant increase in the use of prophylactic anticoagulation in children with COVID-19 vs. those without (84% vs. 40%; p=.0001). Figure 3 shows extended thromboprophylaxis practices upon discharge for COVID related admissions. Almost half of respondents (46%) would not recommend any thromboprophylaxis for children on discharge; 37% would recommend either 2-4 weeks or >4weeks of post-discharge PPX. The majority of adult providers would recommend discharge thromboprophylaxis for adults with 2 weeks post discharge (33%), and 2-4 weeks (30%) being the most common regimens. Conclusion: This pilot survey describes the thromboprophylaxis practices used for adult and pediatric SCD patients by specialty practitioners. In general, practitioners were likely to prescribe pharmacologic thromboprophylaxis for adults while mechanical PPX was preferred for children. However, in the high-risk setting of COVID-19 infection, pediatric practitioners would modify their practice to include pharmacologic thromboprophylaxis. Interestingly, despite the long-term availability of direct oral anticoagulants in adults, and recent completion of pediatric studies, the most commonly used pharmacologic agent pre-COVID in adults and children was enoxaparin. Of note, this survey was conducted prior to release of the International Society on Thrombosis and Haemostasis guidelines regarding discharge PPX in COVID-19. (Spyropoulos AC, J Thromb Haemost, 2020) These results highlight the influence of COVID-19 on the use of pharmacologic thromboprophylaxis, specifically in the pediatric population. Due to frequent hospitalization, studies are needed to guide decision making surrounding VTE PPX for the adult and pediatric inpatient SCD population. Disclosures Davila: Spire Learning: Speakers Bureau; ATHN: Other: Grant Funding. Minniti:Bluebird bio: Consultancy, Research Funding; TauTona: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Emmaus: Consultancy, Research Funding; CLS Bering: Consultancy; Novartis: Consultancy, Research Funding; Global Blood Therapeutics: Consultancy, Research Funding. Desai:Pfizer, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; GBT, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Ironwood Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Rockpointe Continuing Medical Education Company: Consultancy. O'Brien:Bristol Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Enoxaparin used as a form of thromboprophylaxis in children.

Background: There are currently four direct oral anticoagulants (DOACs) approved for the acute treatment and prevention of venous thromboembolism (VTE) in adults. Pediatric hematologists across the United States (US) are using DOACs for their patients based on extrapolated data from adult studies and recently published phase 3 pediatric-specific studies. (Brandao LR, et al. Blood, 2019 and Male C, et al. Lancet Haematol, 2020.) Because further data regarding DOAC use in children are needed, ATHN 15: Characterizing the Real-World Use of Direct Oral Anticoagulants in Pediatric Patients, was developed and is being sponsored by the American Thrombosis and Hemostasis Network (ATHN). The study is being conducted at ATHN-affiliated sites in the US and aims to characterize the real-world use of DOACs in children diagnosed with VTE. ATHN is a nonprofit network of over 140 federally funded hemophilia treatment centers (HTCs) that provides the infrastructure for clinical research and public health surveillance. Methods: Data being captured includes demographics, clinical characteristics, anticoagulation management, and treatment outcomes (bleeding and recurrent thrombosis) of patients Results: As of May 31, 2020, 76 patients from 9 sites have been enrolled (see Table 1 for demographics). Deep venous thrombosis (DVT) of the lower extremities or pelvis is the most prevalent VTE (n = 23, 30.26%), followed by DVT of the upper extremity or upper thorax and pulmonary embolism plus VTE (n = 22, 28.95 and n = 13, 17.1% respectively). 82.89% of patients did not have a history of prior VTE at the time of enrollment. Of the 15 patients with a radiologically confirmed anatomic anomaly, Paget Schroetter/Thoracic Outlet Syndrome and May-Turner Syndrome are the most common (n = 6, 40% and n = 4, 26.7%, respectively). Factor V Leiden heterozygosity, reported in 8 patients, is the most prevalent inherited thrombophilia. Forty-eight patients were identified as having a medical risk factor associated with their VTEs. Sixteen (33.3%) were classified as obese and another 13 (27.1%) had a hospital admission stay greater than 7 days and within 30 days prior to the VTE. At least one specific drug or environmental risk factor was reported in 44 patients. Concomitant use of hormonal contraception (currently taking/stopped within 4 weeks prior to VTE) and the presence of a central venous catheter (present at time of VTE or within 30 days prior to VTE) were the most commonly reported (n = 18, 40.9% and n = 15, 34.09%, respectively). Rivaroxaban is the most prescribed DOAC with 59.2% (n = 45) of patients using this agent. Apixaban and dabigatran use is also reported (n = 29; 38.2% and n = 2; 2.6% respectively). Of the 76 patients, 65 received a different anticoagulant prior to starting a DOAC. Enoxaparin and unfractionated heparin are most commonly prescribed prior to the institution of a DOAC regimen (n = 52, 80% and n = 17, 26.2%). Conclusions: Despite lack of an FDA-approved pediatric indication, hematologists in the US are already using DOACs for children with VTE. Most pediatric patients treated with a DOAC are older than 13 years of age, although we anticipate this will change as providers develop more comfort with these drugs. Interestingly, most of these patients were started on a different anticoagulation regimen prior to starting a DOAC. As enrollment continues, ATHN 15 will serve as a resource for pediatric hematologists to characterize the real-world use of DOACs in children. Further analysis will evaluate DOAC-specific utilization, efficacy and adverse events, including heavy menstrual bleeding. Disclosures Davila: Spire Learning: Speakers Bureau; ATHN: Other: Grant Funding. Corrales-Medina:Bayer: Consultancy; Takeda: Consultancy; Octapharma: Consultancy, Speakers Bureau. Raffini:XaTek: Other: Advisory Board; CSL Behring: Other: Advisory Board; HemaBiologics: Other: Advisory Board; Bayer: Other: Advisory Board; Roche: Other: Advisory Board. Thornburg:Sanofi Genzyme: Consultancy, Other: Data Safety Monitoring Board, Research Funding; NovoNordisk: Research Funding; Genentech: Speakers Bureau; Biomarin: Consultancy, Speakers Bureau; Bayer Pharmaceuticals: Research Funding; American Thrombosis and Hemostasis Network: Research Funding; National Hemophilia Foundation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Ironwood Pharmaceuticals: Consultancy, Other: Data Safety Monitoring Board; Bluebird Bio: Consultancy; Spark Therapeutics: Consultancy. OffLabel Disclosure: Apixaban, Rivaroxaban, Dabigatran and Enoxaparin use in the pediatric population.