Children living with sickle cell can be treated safely using hydroxyurea, study shows
Children living with sickle cell anaemia have no higher incidence of clinically diagnosed infections when treated with hydroxyurea.
New research shows the efficacy and safety of hydroxyurea treatment for sickle cell anaemia, in four low-income sites in Africa, with no increase in clinically diagnosed infections.
Hydroxyurea is a drug taken once daily by mouth that works to reduce the complications of sickle cell anaemia by encouraging the body to produce more fetal haemoglobin, the form of haemoglobin normally made by babies in the womb, that stops red blood cells from sickling.
While hydroxyurea is recommended treatment in high-income countries, doctors have been cautious in low-income settings, because it reduces the number of infection-fighting neutrophils, and could therefore lead to an increased risk of infections where access to clinical services is low.
The study, part of the NIH-funded Realizing Effectiveness Across Continents with Hydroxyurea, (REACH) trial, showed that in fact there was no increase in the incidence or severity of infections, including malaria, in children receiving hydroxyurea treatment.
Living with Sickle Cell
Sickle cell anaemia is the most common and severe inherited blood disease in humans, with approximately 80% of cases occurring in sub-Saharan Africa. Around 550,000 children are born with sickle cell anaemia every year. This results in complications such as pain, vulnerability to infections and chronic ill health. Bacterial and viral infections are a common complication of sickle cell anaemia, including life-threatening infections. In theory, treatment by hydroxyurea could worsen infections including malaria because it dampens the immune system; however, this has not been studied in detail previously.
Treatment of sickle cell anaemia
The study, which is published today in The Lancet Haematology, was carried out at four sites in Africa: Angola, DR Congo, Kenya and Uganda. It involved the treatment of 606 children and young adults living with sickle cell anaemia.
Recruitment of children aged one to ten took place between 2014 and 2016, and patients have been followed up every two to three months since then.
The children who participated in the multicentre trial began hydroxyurea treatment for six months at a fixed dose and were then escalated to the maximum dose they could tolerate. During the trial, most infections were reported retrospectively, usually through clinical history alone rather than through real time testing for infection.
The incidence of malarial and non-malarial infections decreased with increasing hydroxyurea dose. The researchers found that the risk of infection dropped by 51% for malaria and 38% for non-malarial infections.
REACH has been running for more than 10 years and has already shown that hydroxyurea therapy is both safe and highly effective in reducing most sickle-related complications. Through this extended analysis, this latest research shows that hydroxyurea treatment does not increase the risk of serious infections in low-income settings in Africa.
Study lead Professor Tom Williams, Imperial College London's Institute of Global Health Innovation, said: "Many doctors are cautious of using hydroxyurea because they are worried that it will increase the risks of severe or fatal infections. This is particularly true in low-income settings with limited medical resources. In this huge study covering more than 5,000 patient years of follow-up we found no increase of illness or death from infections, even when hydroxyurea is used at the maximum tolerated dose."
Senior author Professor Russell Ware, Cincinnati Children's Hospital Medical Center, said: "These findings provide long-awaited data regarding the long-term safety of hydroxyurea used at maximum tolerated dose in low-income settings. Over 10-years of treatment, the incidence and severity of infections did not increase, and in many cases, were decreased."
The study authors recommend that children with sickle cell anaemia living in low resource settings should receive treatment with hydroxyurea at the maximum tolerated dose.
Professor Williams added: "The results of this study provide strong reassurance that the incidence and severity of infections are not increased with long-term or maximum dose hydroxyurea treatment. These findings support the wider use of hydroxyurea as standard of care."
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