Abstract
BackgroundSickle cell disease (SCD) is an inherited autosomal recessive disorder caused by the replacement of normal haemoglobin (HbA) by mutant Hb (sickle Hb, HbS). The sickle-shaped red blood cells lead to haemolysis and vaso-occlusion. Especially in the first years of life, patients with SCD are at high risk of life-threatening complications. SCD prevalence shows large regional variations; the disease predominantly occurs in sub-Saharan Africa. We aimed to systematically assess the evidence on the benefit of newborn screening for SCD followed by an earlier treatment start.MethodsWe systematically searched bibliographic databases (MEDLINE, EMBASE, Cochrane Databases, and the Health Technology Assessment Database), trial registries, and other sources to identify systematic reviews and randomised controlled trials (RCTs) or non-randomised trials on newborn screening for SCD. The last search was in 07/2020. Two reviewers independently reviewed abstracts and full-text articles and assessed the risk of bias of the studies included. Data were extracted by one person and checked by another. As meta-analyses were not possible, a qualitative summary of results was performed.ResultsWe identified 1 eligible study with direct evidence: a Jamaican retrospective study evaluating newborn screening for SCD followed by preventive measures (prevention of infections and education of parents). The study included 500 patients with SCD (intervention group, 395; historical control group, 105). Although the results showed a high risk of bias, the difference between the intervention and the control group was very large: mortality in children decreased by a factor of about 10 in the first 5 years of life (0.02% in the intervention group vs. 0.19% in the control group, odds ratio 0.09; 95% confidence interval [0.04; 0.22], p < 0.001).ConclusionThe results are based on a single retrospective study including historical controls. However, the decrease of mortality by a factor of 10 is unlikely to be explained by bias alone. Therefore, in terms of mortality, data from this single retrospective study included in our systematic review suggest a benefit of newborn screening for SCD (followed by preventive measures) versus no newborn screening for SCD (weak certainty of conclusions).
Highlights
Sickle cell disease (SCD) is an inherited autosomal recessive haemoglobin (Hb) disorder caused by the replacement of normal Hb (HbA) by mutant Hb
The control group were participants in a historical cohort observation study initiated to provide information on the course of SCD, including 105 SCD-S/S-positive infants identified by screening between 1973 and 1975 (Jamaican Sickle Cell Cohort Study [27, 28]). These infants remained untreated, as no established treatment for SCD was available at that time
As the mortality in children decreased by a factor of about 10 in the first 5 years of life, there was a very large difference between the intervention and the control group, which is unlikely to be explained by bias alone
Summary
Sickle cell disease (SCD) is an inherited autosomal recessive disorder caused by the replacement of normal haemoglobin (HbA) by mutant Hb (sickle Hb, HbS). The sickle-shaped red blood cells lead to haemolysis and vaso-occlusion. Sickle cell disease (SCD) is an inherited autosomal recessive haemoglobin (Hb) disorder caused by the replacement of normal Hb (HbA) by mutant Hb (sickle Hb, HbS). SCD-S/S is the most common type of sickle cell disease; copies of the haemoglobin gene are inherited from both parents. SCD-S/C is the second most common type. The HbC gene is inherited from one parent and the HbS gene from the other. SCD-S/beta0 thalassaemia is a combination of the sickle cell mutation and beta-thalassaemia; one parent passes on a sickle cell allele, the other a beta-thalassaemia allele.
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