Lower alloimmunization rates in pediatric sickle cell patients on chronic erythrocytapheresis compared to chronic simple transfusions.

BACKGROUND: Erythrocytapheresis (ECP), automated red blood cell exchange, is increasingly being used for chronic transfusion therapy in sickle cell disease (SCD) as it is an isovolumetric transfusion, is more effective in lowering hemoglobin (Hb)S, and can limit iron overload. Because ECP requires increased blood exposure compared to simple transfusions there is concern for increased transfusion complications, including alloimmunization. We compared alloimmunization rates between patients receiving simple or exchange chronic transfusions. STUDY DESIGN AND METHODS: Data were retrospectively collected for 45 SCD patients (n = 23 simple, n = 22 ECP) on a chronic transfusion program as of December 2010 to determine the rate of antibody formation (antibodies formed per 100 units transfused). RESULTS: The 45 patients received 10,949 units and formed six new alloantibodies during the study period (1994-2010); therefore, the overall alloimmunization rate was 0.055 alloantibodies per 100 U. There were three antibodies formed in three patients on ECP, one allo (anti-rh(i) ) and two autoantibodies. There were six antibodies in four patients on a simple transfusion program, five allo (anti-Le(a) , M, D, C, and Kp(a) ) and one autoantibody. The ECP group received significantly more blood (338.5 units/patient vs. 152.2 units/patient, p = 0.001). The rate of antibody formation (auto plus allo) was 0.040 antibodies per 100 U in the ECP group and 0.171 antibodies per 100 U in the simple transfusion group (p = 0.04). The alloantibodies formed per 100 units was 0.013 in the ECP group and 0.143 in the simple transfusion group (p = 0.03). CONCLUSION: Chronic ECP should be considered in patients requiring optimal management of HbS levels and iron burden. Concerns about increased alloimmunization with ECP may be unjustified.

Weekend delay in initiation of chemotherapy for acute lymphoblastic leukemia: does it matter?

The Friday afternoon admission of a child with a potential diagnosis of leukemia creates perceived delays in treatment initiation. Although generally not felt to affect prognosis, the effect of a few days delay in chemotherapy for children with acute lymphoblastic leukemia (ALL) has not been fully investigated. We retrospectively analyzed 207 patients consecutively diagnosed with ALL at Children's Hospital & Research Center Oakland from 1995 to 2007 to determine if delay in chemotherapy increased the risk of relapse, death, transfer to the intensive care unit, or bacteremia. Friday admission did not significantly delay chemotherapy initiation with treatment started at a mean of 4.13±2.40 days for Friday admits versus 3.72±1.57 days for all others (P=0.29). There was no significant association between treatment delay days and relapse (P=0.94) or death (P=0.55). In Cox regression analysis, treatment delay was not a predictor of time to relapse (P=0.80) or longer duration of hospitalization (corrected for delay, P=0.15). There were trends toward significant associations between treatment delay and bacteremia (P=0.07) and intensive care unit admissions (P=0.08), although both were associated with shorter, not longer, treatment delays.We were unable to demonstrate a significant effect of delay in chemotherapy initiation for pediatric patients with newly diagnosed ALL on the examined outcome variables.

Current issues in blood transfusion for sickle cell disease.

PURPOSE OF REVIEW: Although blood transfusion has been felt to be a beneficial therapy for sickle cell disease (SCD) since the 1950s, associated complications initially limited this therapy for these patients. With advances now reducing the side effects of transfusion and several landmark studies over the last decade clearly defining the efficacy for decreasing sickle cell morbidity, the indications for transfusion have increased. This review will discuss the indications, methods and goals of transfusion as well as complications and recent changes in transfusion therapy for SCD. RECENT FINDINGS: Recently studies have established the efficacy of transfusion for prevention of stroke, treatment of acute chest syndrome and perioperative transfusion management of SCD. Pulmonary hypertension is increasingly recognized as a significant source of morbidity and mortality and is an evolving indication for transfusion therapy. Phenotypically matching transfused blood has been shown to decrease alloimmunization, and genotyping for antigen matching may help match donors to patients in the future. SUMMARY: The increased use of transfusions may ultimately be balanced by hydroxyurea and other newer therapies developed as the complex pathophysiology of SCD is better understood; however, red cell transfusion is currently the most studied and accepted therapy for most acute and many chronic complications of SCD. Physicians caring for patients with sickle cell disease should be aware of the unique complications and transfusion requirements in this population.

Pulmonary hypertension in hemolytic anemias.

Pulmonary hypertension (PH) has been reported with nearly all forms of the inherited as well as the acquired hemolytic anemias. Recent research investigating the pathophysiology of PH in sickle cell disease and thalassemia has helped elucidate the central role of hemolysis-mediated endothelial dysfunction in the development of PH in these populations. Although the most appropriate treatment of PH in patients with hemolytic anemia is not clearly defined, the associated significant increased risk of death underscores the need for randomized clinical trials in this area.