Wednesday August 22 2007
The amount of children with high blood pressure was actually consistent with other studies
There is a “hidden epidemic” of high blood pressure in children, The Times reported today.
A study has found that doctors are not detecting the condition in children, and the lack of a diagnosis means there is a danger that the condition will remain hidden until later in life, by which point irreparable damage to internal organs will have already occurred.
According to the newspaper, lack of exercise, poor diet and salty foods are to blame for the rise. The high blood pressure epidemic also corresponds to the increase in obesity rates in children.
In the article, Professor Francesco Cappuccio of the University of Warwick warned that the implications of this may be that children and young people are at risk of longer term effects, such as heart attacks and strokes, and could need blood pressure treatment by the age of 40.
The report was based on a study which had estimated that up to one in 20 American children and adolescents has high blood pressure. This was a well-conducted study in the US that appears to show that practitioners are missing the diagnosis of high blood pressure in children. Similar findings would not necessarily be found if the same study was performed in the UK.
The study only investigated the frequency of high blood pressure going unrecorded or undiagnosed and didnt investigate if the levels of hypertension are increasing. The authors actually found the amount of children with high blood pressure to be “consistent with other studies… in the range of 2% to 5%”.
Where did the story come from?
This research was conducted by Matthew Hansen and colleagues at Case Western Reserve University Medical School, Cleveland, Ohio; Oregon and Health Science University School of Medicine, Portland; Metrohealth Medical Centre Cleveland Ohio; and Harvard Medical School, USA. It is unclear who funded the research.
The study was published in the peer-reviewed medical journal Journal of the American Medical Association (JAMA).
What kind of scientific study was this?
This was a longitudinal study designed to investigate how frequently high blood pressure (hypertension) or the predisposing state (prehypertension) went undiagnosed in young people in the US.
The researchers looked at the medical records of 14,187 young people between the ages of three and 18 who had had at least three routine health checks between June 1999 and September 2006.
The researchers then defined their criteria for prehypertension and hypertension and analysed the children’s blood pressure measurements to determine their status. These figures were then compared to the cases where an actual diagnosis of hypertension had been made.
What were the results of the study?
The researchers found that 507 (3.6%) of the children had high blood pressure. Of these, only 131 (26%) had a note of their high blood pressure readings in their medical records, and only 80 (15.8%) were diagnosed as having hypertension.
They also found 485 (3.4%) of children to have prehypertension and of these, only 55 (11%) had a note of this in their medical records.
What interpretations did the researchers draw from these results?
The researchers concluded that hypertension and prehypertension in children were underdiagnosed. They state that although the data was available to make the correct diagnosis, this was not being done. This may in part be due to the fact that there is “lack of knowledge of normal blood pressure ranges” and a “lack of awareness of patient’s previous readings”.
What does the NHS Knowledge Service make of this study?
This well-conducted study appears to show that hypertension is underdiagnosed in this region of the US. There are several important points to bear in mind when interpreting the newspaper report and the findings of this study:
- This study was not designed to examine whether rates of high blood pressure in young children are increasing. It only assessed how frequently high blood pressure is unrecorded or undiagnosed. The authors state that the actual prevalence of hypertension in this age range was found to be “consistent with other studies… in the range of 2% to 5%”.
- There is no way to assess if all of the blood pressure measurements were made with the same level of accuracy, as different measuring instruments and health practitioners would have been involved.
- We cannot assume that the cause of the high blood pressure in this group of people is related to diet and lack of exercise, as the news article reports. Some of the children may have raised blood pressure due to medical causes such as kidney or hormone problems (known as secondary causes of hypertension, which is more common in children than adults).
Sir Muir Gray says...
The study used a threshold to define hypertension. High blood pressure is a risk factor for other diseases, however, the association between blood pressure levels in children and the risk of disease is adult life is unknown.
We do not include blood pressure in the screening of children and this study provides no evidence that we should.