High blood pressure in children used to be relatively rare. Looking at historical data, only a small percentage of children have suffered from this disease. Recently, though, these numbers have started to change, and a growing number of young people are diagnosed with hypertension every year. While some diseases appear to become more common over time because of improvements in detection methods, the rise in the number of pediatric high blood pressure cases is different. The methods used to measure blood pressure haven't changed much in the past 100 years, which means kids today really do have higher blood pressure, on average, than those of just one generation ago.
While the number of children diagnosed with high blood pressure is still low compared to adults, the continuing increase is alarming. For example, in 1989, about 1% of children met the diagnosis guidelines for high blood pressure. In 2002, a follow up study showed that this number had increased to almost 5%. A companion study published in 2003 also demonstrated a disturbing gap between children from different socio-economic backgrounds, with the number of affected children approaching 25% among inner city and minority groups.
One consistent thing in all of these studies is the clear relationship between certain factors:
- High blood pressure is very age-dependent, and is almost non-existent in children under 7 years old
- Young girls suffer from hypertension far less frequently than young boys, regardless of age
- Weight and blood pressure are positively correlated -- as weight increases, so does blood pressure
- Young children usually have secondary hypertension, while older children and teens usually have primary hypertension
Interestingly, the rising number of high blood pressure cases in children seems to be dependent on geography. For example, while the number of cases is rapidly increasing in both the United States and Britain, it is actually falling in some places, such as Northern Ireland. This observation is particularly interesting because it does not appear to be weight related. For example, the number of high blood pressure cases in Northern Ireland is decreasing despite the fact that the average weight is increasing. No completely satisfactory explanation for this phenomenon has been proposed, though there are some studies which suggest that things like decreased salt intake might account for the difference.
Despite isolated geographical trends, the main factor behind the recent rapid increase in high blood pressure diagnoses in children is obesity. Studies tracking the rate of obesity among children, along with average blood pressure, clearly show that the two increase together. As further evidence, when these two conditions are examined more carefully, there is a noticeable time lag between weight increases and high blood pressure increases. In order to decrease the number of high blood pressure cases in children, it will be necessary to address the growing obesity epidemic.
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