Clinical Benefit and Costs’ Evaluation of Erythocytapheresis Compared to Manual Exchange Transfusion for Children with Sickle Cell Disease: A Single Center Experience
Authors: Dedeken Laurence , Lê Phu Quoc , Rozen Laurence , El Kenz Hanane , Huybrechts Sophie , Devalck Christine , Sauvage Delphine , Heijmans Catherine , Ferster Alina 
Published: October 2019

Abstract
Chronic transfusion in sickle cell disease (SCD) remains the gold standard therapy for primary and secondary stroke prevention and is indicated for patients with recurrent severe vaso occlusive crisis (VOC) or acute chest syndrome (ACS). Automatized apheresis (AA) has several advantages compared to manual exchange transfusion (MET): shorter procedure, continuous control of fluid balance, etc. The aim of our study was to assess the safety and efficacy of AA in SCD patients previously treated with MET at Hôpital Universitaire des Enfants Reine Fabiola, Brussels, Belgium and to evaluate the change of the costs related to transfusion and chelation overtime.
From January 2012, the AA program for SCD patients started in our institution. Patients on chronic transfusion program (CTP) and previously treated with MET were eligible to switch to AA if sufficient peripheral venous access to allow AA without the use of central venous line and if weight ≥ 30kg. On CTP, target HbS was <30% in case of stroke risk and <50% for other indications. Data on biological values, duration of the procedure, intervals between procedures as well as adverse events were recorded for the last 6 months on MET and compared to the data on AA. The overall costs of last year on MET, 1st year and 2nd year on AA were analysed. The cost of packed red blood cell (RBC), one-day care facility, apheresis kit and chelation were recorded. For patients on AA for less than 2 years, costs for the 2nd year were extrapolated taking into account the data from the 6 previous months. Data were collected for this analysis until June 2014. Friedman test was used to compare treatment across years and Dunn's Multiple Comparison Test to compare each year of treatment among them.
Ten patients switched from MET to AA at a median age of 11.8 years (range, 9.6-16.8y). The median duration of MET before start of AA was 1.9 years (range 0.5-4.4y). The median duration of AA was 1.7 years (range 1-2.4y). Four patients are on AA for > 2 years, 4 ≥ 20 months and 2 > than 12 months. Indications for CTP were overt stroke (2), pulmonary hypertension (2), recurrent VOC/ACS (5) and poorly tolerated severe anemia (1). All patients remained stable without any SCD related event, except one child who presented seizures without evidence of new stroke and for whom anticonvulsivant therapy was resumed. HbS level remained in the target values for all patients despite a slightly but significantly higher value on AA. The ferritin level and the duration of the procedure decreased significantly (Table 1). The 2 patients on iron chelation stopped it after 10 and 1 AA procedures. Interval between 2 AA was significantly longer than on MET (P<0.0001). On 181 procedures, 9 adverse events (4.9%) required medical intervention: transient hypotension (1), symptomatic hypocalcemia (2), transient headache (2), fever (1), nausea-vomiting (1) and abdominal pain (2). On AA, the requirement of packed RBC was significantly higher than on MET. During the 1st year, costs of AA were significantly higher than MET (132937€ vs.107560€; P=0.01). Nevertheless, during the 2nd year of treatment, the costs of AA were not significantly different from those on MET (102965€ vs. 107560€). Indeed chelation could be stopped in patients previously treated.
AA is useful and safe for SCD patients requiring exchange transfusion program. It is less time consuming for nurses and patients, improves iron overload and interval between 2 procedures is significantly reduced. Despite higher costs related to the increase packed RBC requirement, the costs of AA and MET in the Belgian Health Care System are the same as chelation could be stopped in previously treated patients. Abstract 4091. Table 1.Changes in age, weight, biological data and procedure parameters on MET and on AA On METOn AAP value 1st year 2nd yearMedianRangeMedianRangeMedianRangeMedian age (years)11,89,7-16,812,810,8-17,713,311,8-18,6<0,0001Median weight (kg)45,530,4-66,349,933,8-72,05336,1-76,0<0,0001Median height (cm)153,5138-178161143-180165145-182<0,0001Hb (g/L)9,958,6-10,89,958,8-10,6109,2-11,7NSHb S (%)33,525-424028,5-424631-480,0002Ferritin (µg/L)666182-151225552-8111489-622<0,001Duration of procedure (min)245195-36087,375,5-1269164-1540,0002Interval between procedures (d)2821-293428-35,54228-42<0,0001Packed RBC requirement (ml/kg)18,315,1-2032,227,4-36,13026,8-36<0,0001Packed RBC requirement (unit)39,515-796749-12065,538-137<0,0001

Disclosures
No relevant conflicts of interest to declare.