Blood transfusion for preventing stroke in people with sickle cell disease

Abstract

Background: Sickle cell disease is a common inherited haemoglobin disorder. The abnormal haemoglobin causes distortion of red blood cells, anaemia, vaso-occlusion and dysfunction in virtually any organ system in the body. Stroke occurs in around 10% of children with sickle cell anaemia, and recurrences after a first stroke are likely. Chronic blood transfusion regimes are often used in an attempt to dilute the sickled red blood cells, thus reducing the risk of vaso-occlusion and stroke. However, the side-effects of such regimens can be severe.

Objectives: To assess the relative risks and benefits of chronic blood transfusion regimes in patients with sickle cell disease to prevent a first stroke or further strokes.

Search strategy: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group specialist register which comprises references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings. Date of the most recent search of the Group's specialised register: July 2001

Selection criteria: All those randomised or quasi-randomised controlled trials in which blood transfusion as a preventative measure for stroke in patients with sickle cell disease are compared to an alternative treatment or to no treatment.

Data collection and analysis: Both reviewers independently assessed trial quality and extracted data from the study included.

Main results: One trial was identified by the initial search and this met the inclusion criteria for the review. The trial compared a chronic transfusion regime to maintain sickle haemoglobin at less than 30% with standard care in 130 children with sickle cell disease who were judged to be at high risk of a first stroke through transcranial doppler ultrasonography. Eleven children in the standard care group suffered a stroke during the trial, compared to only one in the transfusion group. Because of this 92% relative risk reduction, the trial was terminated 16 months early. It had been planned that all patients would be treated for 30 months, but median follow-up only 21.1 months. However, a high rate of complications such as iron overload, alloimmunisation and transfusion reactions were seen in the children who were receiving transfusions. No randomised controlled trials were identified which investigated use of transfusion for preventing recurrence of stroke.

Reviewer's conclusions: While the included study demonstrated a significantly reduced risk of stroke in patients receiving regular blood transfusions, the degree of risk must be balanced against the burden of a chronic transfusion regime. Further research is required to establish the use of transfusion in preventing secondary stroke, the age, or length of time after an event, at which transfusion can safely be stopped, and to further define risk factors for stroke in order to reduce the chance of unnecessarily putting children onto a chronic transfusion regime.