Although it might be a rare event, one should be aware of acquired GT as a cause of an unexpected primary disorder of haemostasis in patients with lymphoma or autoimmune disease. The lack of platelet destruction in these cases of acquired GT can be explained, either by the subclass of the autoantibodies (i.e. IgG2 or IgG4) or by the arrested platelet destruction by IgG1 (or IgG3) autoantibodies after splenectomy.

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Objectives Assessment of “real‐world” treatment strategies and outcome in Dutch polycythemia vera (PV) patients. Methods Retrospective chart review in 150 patients with PV (WHO 2008 diagnostic criteria) from 10 major non‐academic hospitals in the Netherlands. Results Patients (median age 64 years, 49% male) frequently had cardiovascular risk factors (56%) and prior vascular events (31%). About 70% of patients were high‐risk, based on ELN criteria. However, the majority of patients were treated with phlebotomies alone (55%). Cytoreduction with hydroxyurea (HU) was received by 44% as part of their initial therapy, with or without phlebotomies. The time to achieve the 45% hematocrit target was shortest in patients treated with phlebotomies with or without HU (125 ± 99 and 197 ± 249 days, respectively) compared to patients treated with only HU (232 ± 216 days). Leukocyte and platelet levels were lower in HU‐treated patients, and ELN response targets were more often reached. During the median follow‐up period of 4.1 years, 14 patients (9%) suffered a thrombotic vascular event. Conclusions In Dutch clinical practice, there is major clinical variation in treatment strategies for PV. Phlebotomizing patients shorten the time to achieve hematocrit control, while HU better controls platelet and leukocyte levels. The thrombotic vascular event rate remains clinically significant.

Background North Middlesex University Hospital (NMUH) is a 400 bed acute hospital in London, United Kingdom. The hospital is a specialist centre for the treatment of inherited red cell disorders caring for approximately 500 adult patients with Sickle Cell Anaemia (SCA) and performing a large number of emergency and elective blood transfusions including automated exchange transfusions, which are an increasingly important cornerstone in the treatment of SCA. In order to minimise risks of allo-immunisation, international guidelines recommend that sickle cell patients are fully phenotyped prior to first transfusion and receive red cell units that are ABO, Rh (DCcEe) and K matched. This has been implemented at NMUH since the 1990s. However, there is concern that the rate of generation of allo-antibodies is still significant. Methods NMUH undertook a retrospective cross-sectional survey of all currently registered adult (>18 years old) patients with haemoglobin genotypes SS and SC, using local transfusion records dating back to 1991. The Laboratory Information Management System (LIMS) was interrogated to provide the current antibody status of each patient as well as the number of red cells received. To account for transfusions before 1991, outpatient annual review data was examined where numbers of units transfused were recorded. Multivariate logistic regression models were used to explore the relationship between the presence of allo-antibodies and the following variables: sex, age, genotype, cumulative number of transfusions and pregnancy. Results A total of 336 patients with HbSS (n=207) and HbSC (n=129) were identified. The mean age was 39. Male to female split was 43% to 57%. In the HbSS group, 73% (n=173) had received at least one blood transfusion. This was 40% (n=52) in the HbSC group. Number of units received ranged from 1 to greater than 500 for those on regular exchange programmes. An estimate of the number of cumulative red cell units given is shown in Figure 1. 18% (n=42) of transfused patients had alloantibodies ranging from 1 (50% of patients) to a maximum of 5 antibodies). 79% (n=33) of those with allo-antibodies were female. 76 antibodies were identified in total and the breakdown of antibody frequency is shown in Figure 2. 38% (n=29) of antibodies were directed against antigens of the MNSs/Fy system and 33% (n=25) were Rh and /K directed. Multivariable regression showed female sex (OR = 3.54; CI 1.55 - 9.00), age (OR = 1.03; CI 1.00 - 1.05) and number of units transfused (OR = 1.40; CI 1.18 - 1.65) were all independent predictors for antibody formation (p<0.05). Subgroup regression analysis of the female patients showed no impact of pregnancy (p>0.05). Conclusion We presented retrospective data from a large cohort of patients with SCA. Limitations included the fact that transfusions prior to 1991 could not be retrieved from the LIMS and were recorded based on annual review data, which although comprehensive, cannot guarantee to fully account for transfusions received elsewhere. The data suggests that despite transfusing in accordance with international guidelines, the level of allo-immunisation remains significant and is particularly marked in females. The majority consisted of potentially hazardous antibodies (Rh/K/Ss/Fy), with only 18% being of limited clinical importance (M/Le). The relatively high frequency of anti-Rh/K requires further investigation to ascertain if these are due to phenotype/genotype mismatch or due to transfusion of inappropriate units at other centres. The high incidence of Ss/Fy antibodies is in line with findings from other papers [Compernolle et al, Transfusion 2018;58;1555-1566] and warrants further research into selecting Ss/Fy compatible units, especially in the younger generation of SCA patients. Disclosures No relevant conflicts of interest to declare.

Background In hematology patients with high risk neutropenia due to intensive chemotherapy the optimal antibiotic treatment duration for fever of unknown origin (FUO) is unknown. Early antibiotic discontinuation has been advocated to reduce unnecessary exposure to broad-spectrum antibiotics, but there is limited evidence for the safety of this strategy. We aimed to assess if short treatment with carbapenems is non-inferior to extended treatment for neutropenic patients with FUO. Methods Multicenter, open-label, randomized clinical trial in 6 centers in the Netherlands. Hematology patients with FUO during high risk neutropenia (≥7 days) were eligible for participation. Eligible patients who gave informed consent were randomly assigned (1:1) to either the short treatment arm, where the carbapenem was discontinued after 72 hours, irrespective of presence of fever, or the extended treatment arm, where the carbapenem was continued for ≥ 9 days until afebrile for 5 days or end of neutropenia (EON), whichever came first. The primary endpoint was treatment failure defined as a composite of recurrent fever or a carbapenem-sensitive infection between day 4 and day 8 and septic shock or death from day 4 until EON. Secondary endpoints included all-cause and infection-related mortality until 30 days post-EON. We used 10% as noninferiority margin. Trial Intervention Flowchart Results Between December 2014 and August 2019 292 patients were included. Risk of treatment failure in the modified intention-to-treat analysis (mITT) was 23.5% (32/136) in the short treatment versus 18.3% (24/131) in the extended treatment arm (adjusted risk difference (ARD) 3.7% (90% CI -2.6% to 9.9%)) and in the per-protocol analysis 27.9% (29/104) versus 18.2% (22/121) (ARD 8.9% (90% CI 0.6% to 17.2%). Short treatment was non-inferior to extended treatment in the mITT population, but not in the per protocol population. All-cause mortality until 30 days post-EON was significantly higher in the short treatment group: 3.7% (5/136) versus 0.8% (1/131) (ARD 2.8%, 95% CI 1.3 to 4.4%), but infection-related mortality until 30 days post-EON was not statistically different between the treatment arms. Primary and Secondary Endpoint Results Subgroup Analyses Results Bloodstream infections after day 3 Conclusion Short treatment with a carbapenem in neutropenic patients with fever was noninferior to extended treatment with regard to treatment failure. Conclusion Summary Disclosures All Authors: No reported disclosures