Several Cochrane Reviews examine the effects of treatments for sickle cell disease, which can cause a huge burden for patients and their families. In a new addition to these in April 2017, Jo Howard from Guy's and St Thomas' Hospitals in London in the UK and colleagues focused on the drug hydroxyurea, which is also known as hydroxycarbamide. She tells us what they found in this podcast.
John: Hello, I'm John Hilton, editor of the Cochrane Editorial unit. Several Cochrane Reviews examine the effects of treatments for sickle cell disease, which can cause a huge burden for patients and their families. In a new addition to these in April 2017, Jo Howard from Guy's and St Thomas' Hospitals in London in the UK and colleagues focused on the drug hydroxyurea, which is also known as hydroxycarbamide. She tells us what they found in this podcast.
Jo: Sickle cell disease is an inherited disorder that creates problems with haemoglobin, the substance in red blood cells that carries oxygen around the body. For people who have sickle cell disease, haemoglobin forms long polymers (or chains) which damage the blood cells and make them stickier, leading to blockages and reduced blood flow that in turn cause pain, strokes and organ damage. It has many other effects as well including depression, poor quality of life, coping issues and poor family relationships; and can require frequent visits to healthcare facilities.
Hydroxyurea or hydroxycarbamide is one of the drugs used to reduce these effects and we did this review to look at its effects on important outcomes such as pain, survival, life-threatening illness and quality of life, as well as side effects.
We found eight randomised trials involving almost 900 people with sickle cell disease. The studies lasted between six and thirty months, which is quite short for a lifelong condition.
Five of the studies recruited both adults and children, and four of these compared hydroxyurea versus placebo, while the fifth randomised participants to receive treatments with hydroxyurea or without it. The other three studies were limited to children who were also at higher risk of having a first or second stroke. In two of these trials, the children received either hydroxyurea and phlebotomy (in other words, collection of blood) or blood transfusion and chelation, which involves the use of agents to remove excess iron from the body. In the other trial, children were randomised to care with or without hydroxyurea.
Our findings suggest that people receiving hydroxyurea experienced significantly fewer pain episodes than those on the comparator treatments, but there’s no evidence that hydroxyurea led to changes in survival, life-threatening illnesses, quality of life or that it caused any particular side effects. However, the studies had limited information on these outcomes, so further research is likely to have an important impact on what we can say about them.
In summary, randomised trials have shown that hydroxyurea is likely to be effective for at least short-term periods for decreasing the frequency of painful episodes in sickle cell disease and doesn’t seem to be associated with an increase in side effects. However, there isn’t much evidence on whether the drug is beneficial when used for many years or whether it causes any long-term side effects. Answers to these important questions will require new studies, designed to run for longer than the trials that have been done up to now.
John: If you would like to read about the eight studies that are already in Jo’s review and watch for future updates if more evidence becomes available, you can find it at Cochrane Library dot com. Just visit the website and search ‘hydroxyurea and SCD’ to see it listed first. If you’d like to see the other Cochrane Reviews for this condition, a simple search for ‘sickle cell’ on its own will list them all.