Impact of chronic transfusion on incidence of pain and acute chest syndrome during the Stroke Prevention Trial (STOP) in sickle-cell anemia

Objective: The Stroke Prevention Trial (STOP) demonstrated that chronic transfusion is highly effective in reducing the risk of stroke in children with sickle-cell disease and an abnormal transcranial Doppler ultrasonography examination result. Our objective was to determine whether chronic transfusion therapy reduces the incidence of pain and acute chest syndrome. Methods: During STOP, 130 children with sickle-cell anemia or sickle beta (0)-thalassemia and abnormal transcranial Doppler ultrasonography examination result were randomly assigned to chronic transfusion (n = 63) or observation (n = 67). In addition to monitoring for stroke, nonneurologic sickle-cell complications were identified and recorded. Results: Mean age at STOP study entry was 8.3 +/- 3.3 years, and mean followup was 19.6 +/- 6.5 months. Hospitalization rates (based on intent-to-treat analysis) for acute chest syndrome were 4.8 and 15.3 per 100 patient-years (P = .0027) and for pain were 16.2 and 27.6 per 100 patient-years (P = .13) in the chronic transfusion and observed groups, respectively. If analyzed according to treatment actually received, the difference in pain rate becomes significant (9.7 vs 27.1 events per 100 patient-years, P = .014), and transfusion remains protective from acute chest syndrome (2.2 vs 16.7 events per 100 patient-years, P = .0001). Conclusions: Compliance with aggressive chronic transfusion reduces the frequency of acute chest syndrome and pain episodes.