Tens of thousands of children are thought to have familial hypercholesterolaemia (FH), an inherited condition that causes abnormally high levels of cholesterol in their blood. People with FH are at risk of heart disease from an early age as the excess cholesterol hardens and narrows their arteries (atherosclerosis).
UK guidelines say that children with FH should follow a healthy diet and exercise programme, and that doctors should consider prescribing them statins by the age of 10 to bring down high cholesterol levels and delay or prevent heart disease.
Because statins are taken long-term, there's concern about possible side effects in children. This study found no evidence of liver toxicity, or of differences in growth. Children with FH were half as likely to be obese as other children, possibly because they are advised to follow a healthy diet.
Because only 300 children's records were included, and not all potential side effects were measured, we can't be sure that no children taking statins would get side effects.
That said, it would certainly seem that the risks of taking statins are likely to be outweighed by the complications associated with poorly treated FH, such as having a heart attack. Doctors will consider the risks and benefits for the individual child, if statins are being considered.
Where did the story come from?
The researchers who carried out the study came from University College London, Royal Gwent Hospital in Wales and the Royal Free Hospital, also in London. The study was funded by the British Heart Foundation, Heart UK, the Cardiac Network Co-ordinating Group Wales, the Royal College of Physicians and the National Institute for Health Research. It was published in the peer-reviewed Journal of Clinical Lipidology on an open-access basis, meaning it is free to read online.
The Mail Online and The Times carried broadly accurate stories about the research. However, they did not point out the limitations of the study.
What kind of research was this?
This was a cohort study using data from a disease register of children diagnosed with familial hypercholesterolaemia (FH). This type of study is useful for spotting patterns and comparing what happened to children on different treatment. However, a study of 300 children may be too small to spot rarer side effects.
What did the research involve?
In 2012, researchers contacted UK cholesterol clinics and paediatricians with an interest in cholesterol disorders to ask them to provide data on their child patients with FH to a national register. Children's medical and family data was collected, as well as information from annual check-ups, including information about their liver enzymes and growth.
Researchers used the data to find out:
- what proportion of children with FH were prescribed statins, and at what age
- the cholesterol levels of children with FH, either on or off statin treatment
- whether any children had records of high levels of liver enzymes, showing potential damage to the liver
- whether children with FH taking statins had different growth rates to children with FH not taking statins
- what proportion of children with FH were overweight or obese
- reasons for children not being prescribed statins
What were the basic results?
The clinics provided data on 300 children, who were followed up for an average 2.7 years. More than half were on statins by the end of the follow-up period, but this varied widely by age group. Statins were not taken by any children under 5, and taken by 16.7% of children aged 5 to 10, 57.1% of those aged 10 to 15, and 73.2% of those aged over 15.
Children taking statins showed a 31% drop in their cholesterol levels compared to their levels at diagnosis, although more than half (55.6%) still had cholesterol over the recommended level of 3.5mmol/litre. Most children aged over 10 who were not treated with statins had cholesterol over 3.5mmol/litre (82.3% at diagnosis).
None of the children taking statins had liver enzyme levels that suggested liver damage, and their growth rate was similar to that of FH children not taking statins.
Children with FH were about as likely to be overweight as children in the general population (16.9% compared to 14.6%) but half as likely to be obese (11.1% compared to 22.1%).
For children over 10 and not taking statins, the most commonly stated reason was that the doctor considered their risk to be low (37.2%). Others were attending their first clinic, trying dietary measures to bring down cholesterol or awaiting test results (31.4%) or expected to start a statin after their clinic visit (14%). Only 12.8% of children were not taking statins because they or their parents refused them. However, there was no reason recorded for 20 of the children.
How did the researchers interpret the results?
The researchers said their results were "reassuring" in that there was no difference in average growth rate between children taking or not taking statins, and none of those taking statins had signs of liver toxicity.
They said their data showed 71 children not taking statins who "would be strong candidates for statin treatment". They said the study found "statin use in children is not associated with any reductions in growth rate and is safe in childhood."
This study is reassuring for parents of children with FH and whose doctors have recommended statins. It shows no evidence of problems arising from the drugs, for children diagnosed with FH and taking statins.
However, we might want to be cautious about the authors' suggestion that many more children should be diagnosed with FH and offered statin therapy. The study has limitations.
For example, the doctors did not routinely record side effects such as muscle pain, which is sometimes a problem for older people taking statins. Adults taking statins are at a small increased risk of getting diabetes, but this study did not address that risk for children. The study was relatively short-term, with less than 3 years' average follow-up from diagnosis, so cannot tell us much about long-term effects. It was also small, reflecting the small numbers of children diagnosed with the condition.
Risks always need to be balanced against benefits. We know that statins reduce the risk of heart disease for adults with FH, and it is likely that children will benefit in the same way. The information from this study will help doctors and parents when discussing whether children with FH should start taking statins.