The follow-up Stroke Prevention Trial (STOP II) attempts to optimize tx therapy for primary stroke prevention in children with SCD who are at increased risk due to an abnormal Doppler ultrasound. A survey of participating investigators (PIs) was performed in order to assess tx practices; 12 PIs out of 26 responded. To begin chronic tx, 42 % of the PIs preferred erythrocytapheresis (ECP), partial or total exchange to bring hemoglobin (Hb) S <30%, 33% used frequent txs over a month, and the rest used either method. For continuation of chronic tx, 5 PIs used only simple tx for their pts, 2 used partial exchange (phlebotomy and simple tx), and 5 used either simple tx or exchange to transfuse their patients (pts). The most common reason to choose a method was intravenous (IV) accessibility. 4 PIs mentioned that they start with simple tx but later might use exchange if unable to keep Hb S <30% or to avoid iron overload. For simple tx, most PIs ordered 10–15 ml/kg leucoreduced, Rh and Kell compatible, S negative packed red blood cells (PRBC). Pts returned for the next tx, depending on prior pre-tx Hb S (goal < 30%), or every 4 weeks unless Hb S was >30%. Most PIs had a post-tx target hematocrit (Hct) 35–36%, but a third of them did not have one. Pre-tx Hct and/or Hb S (but not post-tx values) were used to predict the timing of the next tx by 83% of the group. When performing ECP, the PIs participated in the decision of how much to exchange pts only 33% of the time; generally ECP was planned by a blood bank physician and/or by machine programming. Chelation began either after 12–30 months of tx (median 18 months), or after serum ferritin 1000–2500 ng/ml (median 2000). 67% of the PIs obtained liver biopsies in all or some of the STOP II pts. Indications for liver biopsies were cited as routine for transfused pts (5 PIs) or depending on ferritin values (6 PIs). Deferoxamine 25–50 mg/kg was infused subcutaneously over 8–10 hours 5–7 nights a week in all pts. Eight PIs reported the use of central venous lines (ports) in some pts to facilitate IV access. Barriers cited to effective chronic tx were: pt compliance with chelation (7 reported it as most important), IV access, pt compliance with tx schedule, hypersplenism, and alloimmunization. We conclude that hematologists :(1) Administer leucoreduced Rh and Kell compatible, S negative PRBC to keep pre-tx Hb S levels <30%, (2) use pre-tx Hb S and Hct to predict next tx, usually every 3–4 weeks, (3) monitor and treat iron overload, and (4) report that poor compliance with chelation is a key barrier to an effective tx program. Although liver biopsy to monitor iron stores and partial/total exchange to limit iron overload are accepted interventions, medical practice still varies.
Research and Implementation of Machine Programming Based on Agile Thinking