Study confirms rising global burden of sickle cell anaemia in young children

The global burden of the hereditary blood disorder sickle cell anaemia is increasing: it has been estimated that almost half a million babies will be born with the condition in 2050, according to a mathematical modelling study.

The study – conducted by researchers at the University of Oxford, Imperial College and the KEMRI-Wellcome Trust Research Programme in Kenya – suggests that implementing basic health interventions could significantly reduce death rates in children with the condition aged less than five years. The findings have implications for guiding national policy decisions on public health spending.

The researchers used estimated country rates of sickle cell anaemia (SCA) and information on projected birth rates to show that the number of newborn babies with SCA is likely to increase from roughly 305,800 in 2010 to about 404,200 in 2050.

The biggest rise will be seen in Nigeria, where the number of newborns affected is expected to rise by half as much again, accounting for one-third of all babies born with SCA. The Democratic Republic of Congo and India are the next biggest contributors to the global burden of SCA, although the number of infants affected in India is expected to fall by a quarter by the year 2050.

The authors show that implementing basic health interventions for SCA by 2015 (e.g. newborn screening, penicillin prophylaxis and vaccination) could increase survival of more than five million newborns with SCA by 2050. Similarly, introducing universal screening programs by 2015 could save the lives of almost 10 million newborns with SCA globally, of which 85 per cent will be born in sub-Saharan Africa, over the 35-year period to 2050.

The authors made several assumptions about how the estimated reduced death rates are linked with the introduction of health interventions, and they emphasise that their findings are limited by the uncertainty around these estimates. Nevertheless, by quantifying the increase in the global burden of SCA using evidence-based data, the findings highlight a need for public health planning to limit the future burden of this debilitating disease.

Dr Frédéric Piel from the University of Oxford, who led the study, said: "Our quantitative approach confirms that the global burden of SCA is increasing and highlights the need to develop specific national policies for appropriate public health planning, particularly in low- and middle-income countries."

In an accompanying perspective article, David Osrin and Edward Fottrell of the UCL Institute of Child Health, who were not involved in the study, discuss how the relative burden of child disability with diseases such as SCA will increase as child death rates decrease. They urge the global health community to respond to the changing patterns of disease burdens and stress the importance of studies like this, highlighting the need for both collaborative responses and better data for planning and monitoring.

Sickle cell disorders are caused by an inherited defect in the gene for haemoglobin, the molecule in the blood that is responsible for transporting oxygen around the body. Individuals who inherit one copy of the defective gene usually do not show any symptoms; however, those who inherit two copies of the gene, one from each parent, suffer from SCA and lifelong complications.

The defect causes red blood cells to adopt an abnormal, rigid, sickle shape. In addition to the anaemia caused by the reduction in the amount of oxygen that can be transported around the body, sickled cells can cause blockages in blood vessels, restricting blood flow to organs and causing pain and other clinical complications.

The findings were published online this week in the journal 'PLoS Medicine'.