Implementation of national blood conservation recommendations at an adult sickle cell center

Adding hydroxyurea to chronic transfusion therapy for sickle cell anemia reduces transfusion burden

BACKGROUND

Chronic red blood cell (RBC) transfusion is an established therapy to prevent stroke in patients with sickle cell anemia (SCA). It is unclear if adding daily hydroxyurea treatment to chronic transfusion is beneficial.

STUDY DESIGN AND METHODS

We conducted a phase 2 clinical trial (NCT03644953) investigating the addition of dose-escalated hydroxyurea to chronic transfusion for patients with SCA receiving simple chronic transfusion for stroke prevention. Simple chronic transfusion therapy was administered as per the same protocol before and after hydroxyurea treatment in which the volume transfused was dependent on the pretransfusion hemoglobin (Hb).

RESULTS

A total of 14 participants enrolled with nine completing one year of combination hydroxyurea and transfusion (HAT) therapy after reaching hydroxyurea target dose. No participant who discontinued the study prematurely had a serious adverse event attributed to HAT. Among the nine participants who completed the study, eight participants achieved a reduction in RBC transfusion volume with a median reduction of -19.4 mL/kg/year (interquartile range -31.8, -2.8 mL/kg/year), p = .02, when comparing pre- and post-HAT time periods. With the addition of hydroxyurea participants had a significant increase in pretransfusion Hb S% but this was balanced by an increased Hb F% and decreased lactate dehydrogenase. One participant developed a pretransfusion Hb >11 g/dL and Hb S > 45% that required holding hydroxyurea and changing to partial manual exchange transfusions. No patient had evidence of cerebrovascular disease progression.

DISCUSSION

Hydroxyurea added to chronic transfusion therapy for patients with SCA is feasible and decreases RBC transfusion volume requirements.

Revisiting the benefits of isovolemic hemodilution red cell exchange for sickle cell disease

BACKGROUND

Isovolemic hemodilution red cell exchange (IHD-RCE) is a modified form of the standard red cell exchange (STD-RCE), intended to reduce red cell requirements in patients with sickle cell disease (SCD). This retrospective crossover analysis of nine patients aims to add to the limited existing literature on IHD-RCE and address the equipoise regarding whether the benefits of (a) decreased RBC usage per exchange and (b) increased interprocedure interval (via lower fraction of cells remaining, FCR) can be observed at the same time, in the same patient.

METHODS

At a single center, we identified 37 patients with SCD undergoing chronic RCE between 2014 and 2021. We excluded those patients who did not have at least six consecutive procedures of each type (STD- and IHD-RCE), arriving at nine patients for analysis.

RESULTS

When using greater decreases in hematocrit than previously published, we did not find that IHD-RCE resulted in any clinically apparent adverse events. We did find greater decreases in diastolic blood pressure and increases in heart rate in some patients, as compared to STD-RCE. After correcting for total blood volume, seven of the nine patients had significantly reduced red cell requirements with each IHD-RCE. Because the pattern of achieving a lower FCR than programmed was seen to an equal extent with both IHD-RCE and STD-RCE, none of the nine patients showed any statistical difference in actual FCR between procedure types.

DISCUSSION

Our data do not support the observation of both IHD-RCE benefits, decreased red cell usage per exchange and lower FCR/increased interprocedure interval, simultaneously.