Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment and blinding) and by imprecise results (limited study size for each comparison).
A Cochrane review [Abstract] 1 included 3 studies with a total of 990 subjects. The first study compared an aggressive transfusion regimen (decreasing sickle haemoglobin to less than 30%) to a conservative transfusion regimen (increasing haemoglobin to 10 g/dl) in 604 elective operations in people with sickle cell disease. The conservative regimen was found to be as effective as the aggressive regimen in preventing perioperative complications (aggressive vs. conservative transfusion regimen: OR for perioperative mortality 4.95, 95% CI 0.24 to 103.49; OR for acute chest syndrome 1.10, 95% CI 0.65 to 1.86; OR for painful crisis 0.69, 95% CI 0.35 to 1.37; OR for neurological event 0.99, 95% CI 0.20 to 4.96; OR for renal complication 3.00, 95% CI 0.31 to 29.00), and was associated with fewer transfusion-related adverse events (alloimmunisation 10% in the aggressive transfusion vs. 5% in the conservative group, OR 2.34, 95% CI 1.22 to 4.49; haemolysis, delayed or immediate, 6% in the aggressive group vs. 1% in the conservative group, OR 4.97, 95% CI 1.67 to 14.78).
Two trials (434 participants) compared a preoperative transfusion plus standard care to a group receiving standard care. There was no difference in all-cause mortality between people receiving preoperative transfusions and those receiving no preoperative transfusions (two trials, 434 participants, no deaths occurred).One trial showed a reduced number of people developing acute chest syndrome between people receiving preoperative transfusions and those receiving no preoperative transfusions, risk ratio 0.11 (95% confidence interval 0.01 to 0.80) (65 participants), whereas the other trial did not, risk ratio 4.81 (95% confidence interval 0.23 to 99.61) (369 participants).
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