Childhood BMI cutoffs ‘not adequate’ for predicting CVD risk
MedWire News: Research indicates that international body mass index (BMI) cutoffs for overweight and obesity in childhood are poor predictors of cardiovascular disease (CVD) in adulthood.
Leah Li and colleagues, from University College London in the UK, found that the combined International Obesity Task Force (IOTF) cutoffs for overweight and obesity predicted the presence of CVD risk factors in adulthood with high specificity (low false-positives) but low sensitivity (high false-negatives).
Using data from the 1958 British birth cohort, the team analyzed measures of BMI, collected at age 7, 11, and 16 years, and CVD risk factors (obesity, hypertension, adverse lipid concentrations, and Type 2 diabetes) measured at age 45 years, for over 7000 men and women.
The researchers report that IOTF cutoffs correspond with the percentile curves used by the World Health Organization for respective adult health-related BMI cutoffs of 25 kg/m2 and 35 kg/m2 for overweight and obesity at age 18 years.
Li et al report in the American Journal of Clinical Nutrition that the prevalence of overweight or obesity was low in childhood (<11%), compared with in adulthood (74.9% of men and 56.2% of women).
They show that prediction of adult non-obese status from IOTF cutoffs was high, at 94.8%-95.9%. However, during childhood, a substantial proportion of obese adults - between 75.2% and 84.7% - were not identified by IOTF cutoffs.
Of all the CVD risk factors assessed, childhood BMI best predicted adulthood obesity and risk for Type 2 diabetes. Furthermore, large increases in childhood BMI, particularly between age 7 and 11 years, were significant predictors of these risk factors.
However, the researchers say the predictive value of gains in BMI during childhood was no better for predicting adulthood obesity than measures of BMI at any given childhood age; the corresponding areas under the receiver operating characteristic curve (AUC) were 0.55-0.65 compared with 0.59-0.75.
In addition, compared with childhood BMI, adulthood BMI was a better predictor of risk for Type 2 diabetes and hypertension; the AUCs at 45 years were 0.74 and 0.66, respectively, compared with ≤0.68 and ≤0.54 in childhood.
Li and team conclude that, ideally, BMI cutoffs should have both high sensitivity and specificity, and therefore suggest that population-level approaches should be considered for the prevention of adult CVD risk in the future.
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By Nikki Withers