Evidence mounts to support use of BMI as predictor of hypertension in children
MedWire News: A study investigating the predictive ability of various adiposity indicators for elevated blood pressure (BP) in children highlights additional evidence for the use of body mass index (BMI) instead.
No single adiposity measure exhibits superior ability compared with BMI in identifying children at risk for elevated BP, report Katerina Maximova (University of Alberta, Edmonton, Canada) and colleagues in the Journal of Hypertension.
They used data from the Quebec Adipose and Lifestyle Investigation in Youth study, which included 630 Caucasian families (including pairs of biological parents and their child, aged 8-10 years at baseline).
The researchers investigated whether the adiposity indicators waist circumference (WC), waist-to-height ratio, percentage body fat from skinfold thickness (%BF SF), as well as percentage total fat and percentage central fat (both measured using dual energy X-ray absorptiometry) indicated elevated BP in children more or less accurately than BMI.
They found that all adiposity indicators were highly correlated, with Pearson correlation coefficients ranging from 0.86 to 0.99. In particular, WC was highly positively correlated with measures of total fat mass and central fat mass (r=0.95) and central fat mass was also highly correlated with total fat mass (r=0.99).
All adiposity indicators had a similar and modest ability to identify children with elevated systolic BP (defined as at least 90th age, gender, and height-specific percentile), with areas under the receiver-operating characteristic curve ranging from 0.65 to 0.66 (where 1.00 denotes perfect discrimination).
Neither WC nor waist-to-height ratio were superior to BMI in identifying children with elevated systolic BP, while measures of skinfold thickness and %BF SF were not significantly different, in terms of predictive power, to BMI or WC.
Measures of total and central fat mass also showed no superiority or improved predictive power compared with BMI or WC.
"As BMI measurement is easy to obtain and requires little training, results support current recommendations for the use of BMI in clinical practice and public-health settings to assess adiposity in children, at least in this age group," write the authors.
"Further, as all indicators had a modest ability to identify children with elevated BP, results also support current clinical practice guidelines, which recommend measuring BP in all children of this age independent of a weight status," they conclude.
By Piriya Mahendra