Large Population Dataset Linkage to Understand Evolving Practice in Red Cell and Platelet Transfusion and Clinical Outcomes in Patients with Myelodysplastic Syndromes (MDS): A 15-Year Study

Aim: Transfusions are frequently administered for anemia and thrombocytopenia in MDS. However, evidence to guide transfusion remains sparse, along with data about real-world MDS transfusion practices, transfusion-related outcomes and changes over time with increasing access to disease-modifying therapies. In Australia, from 2011, 5-azacitidine was funded through the Pharmaceutical Benefit Scheme (PBS) for patients with IPSS classification intermediate-2 or high-risk MDS, or Chronic Myelomonocytic Leukemia-2 (CMML-2). Australian Patient Blood Management (PBM) guidelines were also first published in 2011. We aimed to characterise red blood cell (RBC) and platelet transfusion practices, and transfusion-related outcomes of MDS and CMML patients over a 15 year period, and explore whether access to disease-modifying therapies or the introduction of PBM guidelines impacted on transfusion requirements.

Methods: Retrospective longitudinal cohort study including all patients with MDS/CMML admitted to hospitals in Victoria, Australia's second most populous state, from 2002-2017. Data linkage from the Victorian Admissions Episode Dataset (VAED) (contains data from all public and private hospital admissions in Victoria, including all transfusion episodes), the Victorian Cancer Registry and the Victorian Death Index was performed. We analysed transfusion episodes and outcome events (cardiac ischemia/failure, transfusion reactions, bleeding).

Results: 6771 patients with a diagnosis of MDS/CMML reported to the Cancer Registry were included (5970 MDS; 801 CMML). The cohort was elderly (>50% aged 70y and over) and predominantly male (male 61%; female 39%). The majority of patients had a low number of comorbidities (Charlson Comorbidity Score: 60% low (0-2); 32% moderate (3-5); 8% high (≥6)).

Of the 179 patients on 5-azacitidine, 38 (21.2%) commenced prior to 2011 and 141 (78.8%) from 2011 onwards. Patients on 5-azacitidine were more likely to be RBC transfusion dependent (TD) (defined as 2 or more RBC transfusions within 16 weeks) (77.7.1% vs 49.9%, p<0.001) and receive platelet transfusions (54.2% vs 28.6%, p<0.001).

During the study period, the patients had a total of 142,765 hospital admissions. 66,068 (46.3%) admissions involved RBC transfusion, with median 3 admissions (IQR 1-10) per patient and median 14 days (IQR 14-33) between transfusions. 3433 (50.7%) of patients were RBC transfusion-dependent (TD). Comparing pre-and post-2011, the proportion of admissions involving RBC transfusion, median number of RBC transfusion admissions per patient, and rates of RBC-TD decreased (table 1). Cardiac events were common, and more frequent in RBC-TD patients (acute cardiac ischemia 14.6% vs 10.3%, p<0.001; acute cardiac failure 27.3% vs 14.1%,p<0.001).

10,049 (7.0%) admissions involved platelet transfusion. Platelet transfusion admissions increased over time (table 1). Median time between platelet transfusions was 7 days (IQR 4-16). 2436 patients (36.0%) experienced bleeding, including 51.3% of platelet-transfused patients. The commonest bleeding site was gastrointestinal (n=1388, 20.5%). Intracranial bleeding occurred in 175 patients (2.6%). 300 patients (4.4%) died from bleeding complications, with higher bleeding-related mortality in platelet-transfused patients (7.0% vs 3.4%, p<0.001) and RBC-TD patients (5.2% vs 4.0%, p=0.001).

Conclusion: This study highlights the high transfusion burden in MDS patients, and related adverse cardiac and bleeding outcomes and mortality. RBC transfusion requirements reduced over time but platelet transfusions increased. This may be related to changing availability or use of MDS therapies, or clinical transfusion decision-making practices, or both - although national PBM guidelines do not specify a particular hemoglobin threshold for chronically transfused MDS patients, clinicians may be extrapolating from recommendations for restrictive transfusion thresholds in other settings (e.g. critical care, perioperative transfusion). These data will help design future MDS transfusion trials, which should include quality-of-life and health economics outcomes, given the burden of transfusion on these elderly patients.

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