What is the target parameter for transfusion in a patient with Sickle Cell Disease?

From the Guidelines

For patients with sickle cell disease requiring transfusion, the target parameter is to maintain hemoglobin S (HbS) levels below 30% for most indications, with a hemoglobin level generally between 9-10 g/dL. This target is based on the most recent and highest quality study, which suggests that maintaining HbS levels below 30% can reduce the risk of stroke and other complications in patients with sickle cell disease 1.

Key Considerations

• Simple transfusions are appropriate for acute anemia, while exchange transfusions are preferred for acute complications like stroke or acute chest syndrome.
• When performing chronic transfusions for stroke prevention, maintain HbS below 30% and hemoglobin between 9-10 g/dL.
• Transfuse with leukocyte-reduced, phenotypically matched red blood cells to reduce the risk of alloimmunization.
• Extended matching for Rh, Kell, Duffy, Kidd, and other minor antigens is recommended, especially for patients on chronic transfusion regimens.
• Monitor for iron overload with serum ferritin levels every 3 months in chronically transfused patients, and consider chelation therapy when ferritin exceeds 1,000-1,500 ng/mL.

Rationale

The American Society of Hematology 2020 guidelines for sickle cell disease recommend using automated red cell exchange (RCE) over simple transfusion or manual RCE for chronically transfused patients with sickle cell disease 1. The guidelines also suggest that the target HbS%, hematocrit, and overall fluid balance can be precisely programmed with automated RCE 1.

Evidence-Based Recommendations

The evidence suggests that maintaining HbS levels below 30% can reduce the risk of stroke and other complications in patients with sickle cell disease 1. The STOP study, a randomized trial, compared periodic blood transfusion with standard care in children with sickle cell disease and found that the risk of stroke was reduced from 10% per year to <1% per year with transfusion therapy 1.

Clinical Implications

The target parameter for transfusion in patients with sickle cell disease is to maintain HbS levels below 30% for most indications, with a hemoglobin level generally between 9-10 g/dL. This target can help prevent sickling events by reducing the proportion of sickled cells while maintaining adequate oxygen-carrying capacity. The matching protocols can minimize transfusion reactions in this frequently transfused population.

From the Research

Target Parameter for Transfusion in Sickle Cell Disease

• The target parameter for transfusion in a patient with Sickle Cell Disease is to maintain a hemoglobin S (HbS) level of ≤30% or <40% between treatments 2.
• A post-transfusion HbS level of ≤10% can be used as a goal to help maintain an HbS <30% for 1 month, and a post-HbS ≤15% allowed patients to maintain HbS <40% 2.
• The decision to transfuse blood should be aimed to increase tissue delivery of oxygen, and the transfused blood should be HbS negative, Rh and Kell antigen matched 3.
• Predicting the post-transfusion HbS value using estimates of the patient's total hemoglobin and the transfused hemoglobin can be reliably predicted using complete blood cell measurements and simple arithmetic equations 4.

Indications for Blood Transfusion

• Blood transfusion has only limited indications such as acute hemolytic, aplastic or sequestration crises, and chronic transfusion protocols are implemented in cases of strokes or high cerebral blood flow ultrasonic studies as a prophylactic measure 3.
• Exchange blood transfusion is used in some complications of the disease such as acute chest syndrome (ACS), priapism or peri-operatively 3.
• ACS was the leading indication for transfusion, occurring in 32 patients (32.3%), followed by hemolytic crisis in 18 patients (18.2%), stroke prevention in 11 patients (11.1%), and splenic sequestration in eight patients (8.1%) 5.

Management of Sickle Cell Disease

• Manual chronic partial exchange transfusion (MCPET) is safe to prevent iron overload, and is effective and easy to use in patients with SCD 6.
• Hydroxyurea non-compliance was notably high, with 64 patients (64.6%) not adhering to the regimen, highlighting the need for standardized transfusion guidelines and enhanced patient education 5.