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Prophylactic versus selective blood transfusion for sickle cell disease in pregnancy

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Abstract

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Background

Pregnant women with sickle cell disease (HbSS, HbSC and HbSβThal) may require blood transfusion to prevent severe anaemia or to manage potential medical complications. Preventive blood transfusion in the absence of complications starting from the early weeks of pregnancy or blood transfusion only for medical or obstetric indications have been used as management policies. There is currently no consensus on the blood transfusion policy that guarantees optimal clinical benefits with minimal risks for such women and their babies. The present review replaces and updates a Cochrane review that was withdrawn in 2006.

Objectives

To assess the benefits and harms of a policy of prophylactic versus selective blood transfusion in pregnant women with sickle cell disease.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2013) and reference lists of retrieved studies. We did not apply any language restrictions.

Selection criteria

Randomised and quasi‐randomised trials evaluating the effects of prophylactic versus selective (emergency) blood transfusion in pregnant women with sickle cell disease. Trials were considered for inclusion whether the unit of randomisation was at individual or cluster level, however, no cluster‐randomised trials were identified.

Data collection and analysis

Two review authors independently assessed trials for inclusion and assessed trial quality. Two review authors independently extracted data. Data were checked for accuracy.

Main results

Out of six relevant reports identified by the search strategy, two trials involving 98 women with sickle cell anaemia (HbSS) met our inclusion criteria. The two trials were at moderate risk of bias. Overall, there were few events for most of the reported outcomes and the results were generally imprecise. One trial (involving 72 women) reported no maternal mortality occurring in women who received either prophylactic or selective blood transfusion. The same trial (involving 72 women) indicated no clear differences in maternal mortality, perinatal mortality (risk ratio (RR) 2.85, 95% confidence interval (CI) 0.61 to 13.22) or markers of severe maternal morbidity [pulmonary embolism (no events); congestive cardiac failure (RR 1.00, 95% CI 0.07 to 15.38); acute chest syndrome (RR 0.67, 95% CI 0.12 to 3.75)] between the treatment groups (prophylactic blood transfusion versus selective blood transfusion). Prophylactic blood transfusion reduced the risk of pain crisis compared with selective blood transfusion (RR 0.42, 95% CI 0.17 to 0.99, two trials, 98 women); however, the margin of uncertainty around the effect estimate ranged from very small to substantial reduction. One trial (involving 72 women) indicated no differences in the occurrence of acute splenic sequestration (RR 0.33, 95% CI 0.01 to 7.92) and haemolytic crises (RR 0.33, 95% CI 0.04 to 3.06) and delayed blood transfusion reaction (RR 2.00, 95% CI 0.54 to 7.39) between the comparison groups.

Authors' conclusions

Evidence from two small trials of low quality suggests that prophylactic blood transfusion to pregnant women with sickle cell anaemia (HbSS) confers no clear clinical benefits when compared with selective transfusion. Currently, there is no evidence from randomised or quasi‐randomised trials to provide reliable advice on the optimal blood transfusion policy for women with other variants of sickle cell disease (i.e. HbSC and HbSβThal). The available data and quality of evidence on this subject are insufficient to advocate for a change in existing clinical practice and policy.

PICOs

Population
Intervention
Comparison
Outcome

The PICO model is widely used and taught in evidence-based health care as a strategy for formulating questions and search strategies and for characterizing clinical studies or meta-analyses. PICO stands for four different potential components of a clinical question: Patient, Population or Problem; Intervention; Comparison; Outcome.

See more on using PICO in the Cochrane Handbook.

Plain language summary

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Blood transfusion policies for sickle cell disease in pregnancy

Sickle cell disease is an inherited disorder of haemoglobin, the protein in red blood cells that carries oxygen. In this condition, an abnormal haemoglobin S from one parent is combined with another abnormal haemoglobin from the other parent. Haemoglobin S inherited from both parents (genotype HbSS), described as sickle cell anaemia is the most common form.

When oxygen tension is low, haemoglobin S crystallizes and makes the red blood cells sickle shaped. Sickling reduces red blood cell capacity to manoeuvre through very small blood vessels causing vascular blockage and early destruction of red cells. The breakdown of red blood cells and massive pooling of damaged red blood cells in the liver and spleen cause anaemia. Acute illnesses include painful crises, pulmonary embolism, acute chest syndrome and congestive cardiac failure. Therefore, pregnant women with sickle cell disease require careful management.

Depending on the institutional policy, blood transfusion can be given at intervals to a pregnant HbSS woman with relatively few or no symptoms to improve the oxygen carrying capacity of blood by increasing haemoglobin blood concentration and lowering haemoglobin S levels; or only when indicated by the development of medical or pregnancy complications. Giving blood at frequent intervals carries the risks of blood‐borne infections and excessive levels of iron.

This review set out to determine whether giving blood at intervals before serious complications occur compared with giving blood only when medically indicated makes a difference to the health of the mother and her baby. The review authors included two controlled trials that randomised 98 women with sickle cell anaemia (haemoglobin SS) before 28 weeks of gestation to one of the two blood transfusion policies. The two trials were of low quality. One trial (72 women) indicated no difference in severe ill health and death of the mother or newborn. There was no difference in the risk of delayed blood transfusion reaction. The two trials suggested giving blood at frequent intervals marginally reduced the risk of pain crisis, with a large degree of uncertainty about the size of the effect, compared with giving blood only when medically indicated. Blood transfusion was delivered at a ratio of four or five to one for prophylactic versus selective blood transfusion, respectively.

Overall, available evidence on this subject is insufficient to advocate for a change in clinical practice and policy.