The STOP study was the first randomized trial of primary stroke prevention in sickle cell disease (Hb SS). 130 Hb SS children, age 2-16, at risk for stroke by Transcranial Doppier (TCD) were randomized to standard care (STC) (n=67) or transfusion (Tx)(n=63). There were no significant clinical or hématologie differences between the two groups except for a lower Hb (7.2 vs 7.6 g/dl, p=.001 ) and Hct (20.4 vs 21.7%, p=.002) in the Tx arm. Tx arm patients (transfused every 3-4 weeks to maintain Hb S <30%) maintained higher pre-TxHb(9.1 vs 7.8 g/dl), Hct (27.1 vs 22.4%), lower relics (7.8% vs 12.7%), ROW (17.0 vs 21.6%, p=.OOOI), and platelets (356 vs 387K, p=.04). WBC did not differ significantly between the two arms (11.4 for Tx vs 11.9 for STC, p=.34). Bilirubin (2.8 vs 4.2 mg/dl, p=.0001) and LDH (593 vs 732, p=.0003) were also lower in patients in the Tx arm. Mean pre-Tx Hb S was 21.5±10.6%. As of 08/00, the total number of strokes is 17(15 STC, 2 Tx arm). Hematologie parameters were not significantly different in the 17 stroke patients from the remainder of the STC arm (n=50) except for a higher WBC (13.1 vs 11.8, p=0.046). Deletional a-thal (-013.7) was seen in 15.5% of the entire randomized group, significantly lower (p=.001) compared to 32.1% for 1294 unselected Hb SS patients <16 years of age in CSSCD. Only 2/17 stroke patients had a-thal (11.8%, p<.001). The distribution of S haplotypes for the 130 patients (55% BEN, 25.7% CAR, 13.1% SEN, 2.3% CAM and 3.9% atypical) was not significantly different compared to CSSCD; however, among the 17 stroke patients, SEN haplotype was underrepresented (8.8%) and CAM appeared to be higher (8.8%). These observations confirm earlier reports of a protective effect of a-thal against stroke in Hb SS patients (Hsu et al, 2000). Also, among patients in the STC arm, high WBC appears to be a risk factor for subsequent stroke. Significant changes were observed in Hb, Hct, retic count, platelets, bilirubin, and LDH with Tx. The precise mechanism(s) whereby Tx reduces the stroke risk is unknown. Potential mechanisms include improvement in anemia, decrease in circulating sickle RBC, decrease in hemolysis, decrease in reticulocyte count, suppression of sickle erythropoiesis, and modification of the hypercoagulable state (decrease in platelets and presumably in platelet activation).
|Original language||English (US)|
|Issue number||11 PART II|
|State||Published - Dec 1 2000|