Kinderen en hoge bloeddruk*
Uit een analyse van meer dan 50 studies van de afgelopen veertig jaar lijkt het volgens de wetenschappers verstandig de bloeddruk bij kinderen al goed in de gaten te houden. Kinderen met
hogere bloeddruk hebben nl. een zeer grote kans om als volwassenen ook hoge bloeddruk te hebben met alle gezondheidsproblemen
van dien.
High Blood Pressure In Childhood Usually Continues Into Adulthood
US researchers reviewing published studies covering up to forty years found that children with high blood pressure usually continue to have high blood pressure as
adults.
The research was the work of senior author Dr Youfa Wang and colleague Dr Xiaoli Chen from the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland and is published online in the journal
Circulation.
Wang, who is associate professor with the Bloomberg School's Center for Human
Nutrition, said:
"The blood pressure tracking data indicate that children with elevated blood pressure levels often grew up to become adults with elevated blood pressure."
"It is important to monitor blood pressure in children since early detection and intervention could prevent hypertension and related disease risks later in life," he added, explaining that the research showed that even slightly raised blood pressure in adulthood considerably raised the future risk of cardiovascular
disease.
In their background information, Wang and Chen, who is a former postdoctoral research fellow in the Bloomberg School's Department of International Health, wrote that while there have been many studies that followed childhood blood pressure into adulthood, their results have been inconsistent and not many have been analysed systematically.
To reddress this gap, they carried out a systematic review and meta-analysis of 50 cohort studies that followed the systolic (when the heart contracts) and diastolic (when the heart relaxes) blood pressure levels of children into
adulthood.
(A meta-analysis is a way of pooling the data from separate studies examining the same variables and re-analysing them using statistical tools as if they were one big study.)
To find the studies they searched the well known database PubMed for articles on tracking blood pressure from childhood into adulthood published between January 1970 and July 2006. From the 301 they retrieved, only 50 of them met the inclusion criteria for the review, providing 617 data points for systolic and 547 for diastolic blood pressure readings for inclusion in the meta-analysis. So this gave a data set that would be equivalent to running a study of around 600 participants, although this figure should be only be used to convey a "feel" for the size of the analysis
task.
The data set covered blood pressure readings taken at various ages and follow up periods, with some covering some forty years of continuous monitoring across many countries and
continents.
Wang and Chen also extracted data on the characteristics of the samples and the blood pressure measurement protocols. They processed the data using statistical tests called Fisher z transformation and random-effects meta-regression analysis. From this they were able to determine the strength of the "tracking" of blood pressure from childhood into adulthood. A strong tracking meant the blood pressure readings remained fairly consistent.
The results showed that:
· The blood pressure tracking correlation coefficients varied from -0.12 to 0.80 with an average of 0.38 for systolic, and from -0.16 to 0.70 with an average of 0.28 for diastolic blood pressure.
· Blood pressure tracking varied significantly by age when participants started being measured (baseline) and how long they were tracked for into adulthood (length of follow up).
· The strength of the tracking increased significantly with baseline age and decreased significantly with follow up length, both for systolic and diastolic readings.
· Blood pressure tracking did not vary markedly by number of readings, race or other population groups.
Wang and Chen concluded that:
"Data from diverse populations show that the evidence for BP [blood pressure] tracking from childhood into adulthood is strong."
Since this strongly suggests that "childhood BP is associated with BP in later life", they also concluded that "early intervention is important".
Chen said they found the degree of blood pressure tracking between childhood and adulthood varied widely, as previous studies had indicated, but when they analysed the overall pooled results they found a "moderate
tracking".
"In addition we discovered that older children seem to have a stronger blood pressure tracking into adulthood," said Chen, adding
that:
"The longer the follow-up study period between the measures collected in childhood and adulthood, the weaker the blood pressure
tracking."
The American Heart Association estimates there are nearly 73 million adult Americans living with high blood pressure, a modifiable risk factor for cardiovascular disease that can result in heart disease, heart failure, stroke, kidney failure and other health
problems.
Wang also worked on a previous study where he and his co-researchers found that about 60 per cent of America adults were either pre-hypertensive or hypertensive in 1999 to 2000, an increase of around 10 per cent compared to a 198-94 national survey, with some groups affected more than others. Wang said this was because of the growing obesity epidemic.
But high blood pressure is a modifiable risk factor, and if there is evidence, as suggested here, that high blood pressure in childhood persists into adulthood, then intervention needs to start early in life. Wang recommended that:
"Lifestyle modification such as eating a healthy diet and having adequate exercise is preferred to medication when appropriate to help young people to control their elevated blood pressure to a desirable level."
"Tracking of Blood Pressure From Childhood to Adulthood. A Systematic Review and Meta-Regression Analysis."
Xiaoli Chen and Youfa Wang.
Circulation, doi:10.1161/CIRCULATIONAHA.107.730366 (Augustus
2008)
