Body mass index vs. deuterium dilution method for establishing childhood obesity prevalence, Ghana, Kenya, Mauritius, Morocco, Namibia, Senegal, Tunisia and United Republic of Tanzania
Objective To compare the World Health Organization (WHO) body mass index (BMI)-for-age definition of obesity against measured body
fatness in African children.
Methods In a prospective multicentre study over 2013 to 2017, we recruited 1516 participants aged 8 to 11 years old from urban areas of
eight countries (Ghana, Kenya, Mauritius, Morocco, Namibia, Senegal, Tunisia and United Republic of Tanzania). We measured height and
weight and calculated BMI-for-age using WHO standards. We measured body fatness using the deuterium dilution method and defined
excessive body fat percentage as > 25% in boys and > 30% in girls. We calculated the sensitivity and specificity of BMI z-score > +2.00
standard deviations (SD) and used receiver operating characteristic analysis and the Youden index to determine the optimal BMI z-score
cut-off for classifying excessive fatness.
Findings The prevalence of excessive fatness was over three times higher than BMI-for-age-defined obesity: 29.1% (95% CI: 26.8 to 31.4;
441 children) versus 8.8% (95% CI: 7.5 to 10.4; 134 children). The sensitivity of BMI z-score > +2.00 SD was low (29.7%, 95% CI: 25.5 to
34.2) and specificity was high (99.7%, 95% CI: 99.2 to 99.9). The receiver operating characteristic analysis found that a BMI z-score +0.58
SD would optimize sensitivity, and at this cut-off the area under the curve was 0.86, sensitivity 71.9% (95% CI: 67.4 to 76.0) and specificity
91.1% (95% CI: 89.2 to 92.7).
Conclusion While BMI remains a practical tool for obesity surveillance, it underestimates excessive fatness and this should be considered
when planning future African responses to the childhood obesity pandemic.
Auteur(s) : Adama Diouf, Theodosia Adom, Abdel Aouidet, Asmaa El Hamdouchi, Noorjehan I Joonas, Cornelia U Loechl, Germana H Leyna, Dorcus Mbithe, Thabisile Molea
Pages : 772-781
Année de publication : 2018
Revue : Bulletin World Health Organisation
N° de volume : 96
Type : Article
Mise en ligne par : DIOUF Adama