Red Blood Cell Storage Duration and Outcomes For Acute Chest Syndrome In Children and Young Adults With Sickle Cell Disease

Red Blood Cells (RBCs) undergo physical and metabolic changes during storage. The clinical impact of the storage duration of transfused blood remains unclear. There is no published literature investigating the storage duration of transfused RBCs as it pertains to outcomes in patients with Sickle Cell Disease (SCD), yet surveys of RBC transfusion practices indicate that 50-60% of pediatric centers preferentially transfuse RBCs of shorter storage duration to patients with SCD. SCD patients with Acute Chest Syndrome (ACS) often require RBC transfusions to improve oxygenation and prevent or treat respiratory failure. The objective of our study is to determine if there is an association between the storage age of transfused RBCs and clinical outcomes for SCD patients with ACS.

In this retrospective cohort study, we included patients aged </= 22 years old with hemoglobin SS, hemoglobin SC, hemoglobin S-β⁰ thalassemia, hemoglobin S-β⁺ thalassemia or hereditary persistent fetal hemoglobin, diagnosed with ACS that were treated with at least one RBC transfusion between January 2007 and May 2012. We excluded episodes of ACS treated with exchange transfusion, and patients with a history of stem cell transplant or receiving chronic RBC transfusion therapy at the time of the ACS episode. ACS was defined as an infiltrate on chest x-ray consistent with a consolidation (not atelectasis) in addition to at least one of the following symptoms: cough, fever >/= 38.5 degrees Celsius, age-defined tachypnea, wheezing or chest pain. The primary outcome measure was length of hospital stay (LOS) after transfusion. Secondary outcomes included duration of supplemental oxygen and IV opioid utilization after transfusion. All analyses utilized the storage age of the oldest unit transfused per ACS episode if multiple units were given. Storage age of RBC units was dichotomized as less than or greater than 14 days, and less than or greater than 21 days (van de Watering, 2011). Outcomes were tested versus each resulting categorical variable. Multiple episodes of ACS in the same patient were analyzed as separate events. Non-parametric data is presented as median (interquartile range (IQR)). The Mann-Whitney U test was used to compare median values between groups tested. Future examination of the data will include generalized linear modeling with multivariate analysis. SPSS version 20 (Armonk, NY) was used for all statistical analyses.

One hundred and forty-six episodes of ACS in 85 patients (46 male, 39 female, 77 HbSS, 1 HbSC, 4 Hb Sβ⁰, 1 Hb Sβ⁺, 2 HPFH) were included. Median (IQR) age of the patients was 8.9 (5.5-13.5) years. Median (IQR) storage age of the oldest unit of transfused RBCs was 18.5 (12.0-27.0) days. Median (IQR) volume transfused standardized by weight was 12.7 (10.6-16.9) mL/kg, with 29/146 (19.9%) receiving more than one RBC transfusion. In all 146 episodes of ACS, median (IQR) LOS after transfusion was 3.0 (2.0-5.0) days. Supplemental oxygen was required prior to transfusion in 109/146 (74.7%) of ACS episodes and for a median of 2.0 (1.0-3.0) days after transfusion. IV opioids were administered prior to transfusion in 93/146 (63.7%) of ACS episodes and for a median of 3.0 (2.0-6.0) days after transfusion. Table 1 describes outcomes compared with RBC age thresholds of 14 and 21 days.

We did not identify an association between storage duration of transfused RBCs and clinical outcomes in pediatric and young adult SCD patients with ACS in this hypothesis generating, retrospective cohort study. These preliminary data do not support the commonly practiced, preferential transfusion of RBCs of lesser storage duration in this population. Prospective, randomized, controlled trials are needed to determine if the common practice of transfusing RBCs of decreased storage age is beneficial in children and young adults with SCD.

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No relevant conflicts of interest to declare.