Red blood cell alloimmunization in myelodysplastic syndromes: Associations with sex, DAT-positivity, and increased transfusion needs.

BACKGROUND: Many patients with myelodysplastic syndromes (MDS) need repeated red blood cell transfusions which entails a risk of immunization and antibody formation. Associations between alloantibodies, autoantibodies and increased transfusion requirements have been reported, but their relationship remains unclear. In this study, we analyzed factors potentially associated with red blood cell alloimmunization, as well as changes in transfusion intensity and post-transfusion hemoglobin increments. METHODS: In a retrospective cohort study, we linked Swedish MDS patients diagnosed between 2003 and 2017 to transfusion and immunohematology data. Potentially associated factors were analyzed using Cox proportional hazards regression. The transfusion rate after detected alloimmunization was analyzed using a fixed effects Poisson regression. Post-transfusion hemoglobin increments before and after alloimmunization were compared using a mixed effects regression. RESULTS: Alloantibodies following MDS diagnosis were detected in 50 out of 429 patients (11.7%). Female sex and a positive direct antiglobulin test (DAT) were independently associated with alloimmunization, with hazard ratios of 2.02 (95% confidence interval [CI] 1.08-3.78) and 9.72 (95% CI, 5.31-17.74), respectively. The transfusion rate following alloimmunization was increased with an incidence rate ratio of 1.33 (95% CI, 0.98-1.80) and the post-transfusion hemoglobin increment after alloimmunization was 1.40 g/L (95% CI, 0.52-2.28) lower per red blood cell unit (p = .002) compared to before alloimmunization, in multivariable analyses. DISCUSSION: Alloimmunization against blood group antigens was associated with sex, DAT-positivity, increased transfusion needs, and lower post-transfusion hemoglobin increments. These findings warrant further investigation to evaluate the clinical significance of up-front typing and prophylactic antigen matching in patients with MDS.

A longer duration of red blood cell storage is associated with a lower hemoglobin increase after blood transfusion: a cohort study.

BACKGROUND: RBC concentrates are commonly stored for up to 42 days but there has been conflicting evidence on the effect of storage duration and clinical outcomes. Most clinical studies have focused on possible associations between duration of storage time and risk for adverse outcomes, including mortality. Recent clinical trials did not find any such associations, but fewer studies have addressed whether storage time affects component efficacy. The main aim of this study was to determine the effect of RBC storage time on hemoglobin increment in transfused patients. STUDY DESIGN AND METHODS: Transfusion data on a cohort of patients with myelodysplastic syndromes were linked to hemoglobin measurements taken between 2 days before and 28 days after a transfusion episode. We applied a mixed-effect linear regression model, accounting for patient characteristics and time from transfusion to next hemoglobin measurement, to study the effect of RBC storage on the hemoglobin increment. RESULTS: The study population consisted of 225 patients who received 6437 RBC units. Compared to units stored less than 5 days, transfusion of blood units stored 5 to 9, 10 to 19, 20 to 29, or 30 or more days resulted in hemoglobin increases that were 0.83 (95% confidence interval [CI], 0.24-1.41), 0.92 (95% CI, 0.34-1.51), 1.33 (95% CI, 0.65-2.02) and 1.51 (95% CI, 0.58-2.43) g/L lower, respectively, per RBC unit. Results were consistent in sensitivity analyses. CONCLUSIONS: Longer RBC storage was associated with a smaller increase in hemoglobin concentration after transfusion. Although statistically significant, the effect was modest, and its clinical relevance in subgroups of patients should be investigated in prospective clinical trials.

Blood use in hematologic malignancies: a nationwide overview in Sweden between 2000 and 2010.

BACKGROUND: Patients with hematologic malignancies receive large numbers of blood transfusions, and transfusion practices for this patient group are increasingly being scrutinized by randomized controlled trials. However, no studies so far have presented current transfusion statistics on a population level for this patient group. STUDY DESIGN AND METHODS: A retrospective descriptive study was conducted that was based on the Scandinavian Donations and Transfusions Database (SCANDAT2), which includes data on all blood donations and transfusions in Sweden and Denmark since the 1960s. Incident cases of hematologic malignancies were identified in the Swedish Cancer Register between 2000 and 2010. Cases were divided into nine patient groups based on diagnosis. RESULTS: A total of 28,693 patients were included in the cohort. Overall, the transfusion pattern varied depending on diagnosis and age. Patients with aggressive and acute diagnoses generally received more transfusions with immediate decline in transfusion incidence after diagnosis, whereas chronic diagnoses generally maintained more stable, but lower, transfusion incidence. In general, patients with leukemia received more transfusions than patients with lymphoma, and patients with acute leukemia as well as patients that had undergone allogeneic stem cell transplantations received the most transfusions. Within 2 years after diagnosis, patients with acute myeloid leukemia diagnosed at ages 0 to 65 years received on average between 30 to 40 red blood cell transfusions and platelet transfusions, respectively, corresponding to direct material costs close to 200,000 SEK (23,809 USD). CONCLUSION: Results from this population-based overview of blood use in hematologic malignancies showed high variability depending on diagnosis and age.