Algorithm for Apherisis Monitoring and Prescription Assistance in Sickle Cell Patients (ALGODREP)
Algorithm for Apherisis Monitoring and Prescription Assistance in Sickle Cell Patients (ALGODREP)
The main objective of this study is to prove the superiority of a procedure which calculates
 the volume of RBCs to transfuse and the time between apheresis based on this algorithm,
 compared to the current procedure. The primary endpoint would be the number of patients with
 individually achieved objectives in terms of % HbS before each apheresis (which reflects the
 effectiveness of the previous apheresis) over a period of 12 months. The secondary objectives
 would be to compare the volume differences of transfused RBCs in both groups over a period of
 12 months, the occurrence of clinical events and the satisfaction of patients and physicians.

 The investigators hope that this study would improve the efficiency and the performance of
 apheresis in sickle cell patients. The investigators also hope to facilitate the organization
 of procedures with the flexibility that would allow the use of this algorithm.
Sickle cell disease (SCD) is the most common genetic disease leading to abnormal hemoglobin
 (HbS). Chronic complications can be severe and affect multiple organs. Among them,
 cerebrovascular disease is one of the most serious leading to a high risk of stroke. These
 complications often require blood exchange transfusions (BET) in order to replace red blood
 cells (RBC) containing HbS (from patients) by GR containing HbA (blood donors), and thereby
 stop the harmful pathophysiological cascade. The indications of long-term apheresis are
 mostly, but not exclusively, represented by cerebral vasculopathy (85% in our center), and
 chronic organ damages. Long-term BET in cerebral vasculopathy may considerably reduce the
 risk of stroke while stopping them leads to a recurrence of this risk, hence there is a need
 to do them regularly (on average every 4 to 6 weeks) with an objective of HbS ≤ 30%. This
 objective may be less stringent in the case of other indications.

 Two methods are used: a manual method which is feasible anywhere and the apheresis which is
 preferred because of its better efficacy in achieving the targets of HbS percentage. It also
 limits transfusion hemochromatosis.

 The volume required for BET by apheresis as well as the optimal period between apheresis
 sessions are empirically determined.

 In our practice, the investigators noticed that this method did not allow to steadily
 obtaining the %HbS objective and the interval between apheresis was variable, in part
 conditioned by the availability of machines. This implies a real risk of occurrence of
 recurrent stroke in patients with cerebral vascular disease and may cause a lack of
 flexibility in the timing of appointments.

 Thereby the principal investigator and the biostatistician created an algorithm to compute
 the volume of blood to be transfused and the interval between apheresis which are necessary
 to maintain an individual objective of HbS percentage. This algorithm has been obtained by
 statistical analysis of apheresis performed at Henri Mondor Hospital over a period of 3
 years.
Inclusion Criteria:

 -  Age 18 years or older

 -  Have sickle cell disease, defined as those individuals with HbSS or HbSβ0Thal

 -  Included in a Blood Exchange Transfusion program (apherisis)

 -  Benefiting from social insurance

 -  Accepting to participate in the study and having signed the informed consent

 Exclusion Criteria:

 -  Have sickle cell disease defined with S-β+thal

 -  Receiving EPO treatment

 -  Pregnant or breast-feeding women

 -  Lack of effective contraception in women in childbearing age

 -  Patient under guardianship