The effect of long-term red blood cell transfusions on chronic chest complications of sickle cell disease

Review question

We reviewed the evidence to see if regular long-term red blood cell transfusions helped to reduce the occurrence or progression of chronic chest complications compared to hydroxycarbamide (hydroxyurea), any other treatment or standard care in people with sickle cell disease.

Background

Oxygen is transported from our lungs to all parts of our body by haemoglobin, which is a major component of red blood cells. Sickle cell disease is an inherited disorder of haemoglobin. In people with sickle cell disease red blood cells become rigid once they have given up their oxygen and are often shaped like crescents. These rigid cells can block blood vessels, which causes problems throughout the body, including the lungs. The two most common chronic chest complications due to sickle cell disease are pulmonary hypertension and chronic sickle lung disease. Pulmonary hypertension is high blood pressure in the pulmonary arteries (the arteries that supply blood to the lungs). High blood pressure in these arteries are associated with an increased risk of death. Chronic sickle lung disease arises as a result of lung damage and loss of lung tissue.

Regular blood transfusions for people with sickle cell disease reduce the amount of the person's own sickled cells in their blood by replacing them with donated, non-sickled cells. Regular transfusions have already been shown to reduce the risk of strokes in people with sickle cell disease.The aim of this review was to find out if regular long-term blood transfusions in people with sickle cell disease lead to a reduction in new chronic chest complications or slowed the progression of any chronic chest complications that have already developed. It also aimed to consider death rates due to chronic chest complications and any adverse effects of the transfusion programme.

Study characteristics

The evidence is current to March 2016. We found no studies in this update of the review.

Key results

There are no results because we found no relevant randomised controlled trials. We would need to design a study with at least 946 participants to be able to detect a decrease in the number of people who died from 12 in 100 to six in 100.

Quality of the evidence

There is no evidence from randomised controlled trials to answer our review questions.

Authors' conclusions: 

There is a need for randomised controlled trials looking at the role of long-term transfusion therapy in pulmonary hypertension and chronic sickle lung disease. Due to the chronic nature of the conditions, such trials should aim to use a combination of objective and subjective measures to assess participants repeatedly before and after the intervention.

Read the full abstract...
Background: 

Sickle cell disease is a genetic haemoglobin disorder, which can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Sickle cell disease is one of the most common severe monogenic disorders in the world, due to the inheritance of two abnormal haemoglobin (beta globin) genes. The two most common chronic chest complications due to sickle cell disease are pulmonary hypertension and chronic sickle lung disease. These complications can lead to morbidity (such as reduced exercise tolerance) and increased mortality.

This is an update of a Cochrane review first published in 2011 and updated in 2014.

Objectives: 

We wanted to determine whether trials involving people with sickle cell disease that compare regular long-term blood transfusion regimens with standard care, hydroxycarbamide (hydroxyurea) any other drug treatment show differences in the following: mortality associated with chronic chest complications; severity of established chronic chest complications; development and progression of chronic chest complications; serious adverse events.

Search strategy: 

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register. Date of the last search: 25 April 2016.

We also searched for randomised controlled trials in the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1, 26 January 2016), MEDLINE (from 1946), Embase (from 1974), CINAHL (from 1937), the Transfusion Evidence Library (from 1950), and ongoing trial databases to 26 January 2016.

Selection criteria: 

We included randomised controlled trials of people of any age with one of four common sickle cell disease genotypes, i.e. Hb SS, Sß0, SC, or Sß+ that compared regular red blood cell transfusion regimens (either simple or exchange transfusions) to hydroxycarbamide, any other drug treatment, or to standard care that were aimed at reducing the development or progression of chronic chest complications (chronic sickle lung and pulmonary hypertension).

Data collection and analysis: 

We used the standard methodological procedures expected by Cochrane.

Main results: 

No studies matching the selection criteria were found.

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