Accuracy of different cutoff points of body mass index to identify overweight according to body fat values estimated by DEXA

Prevalence of overweight and obesity among saudi children: A comparison of two widely used international standards and the national growth references

Objective

To compare three body mass index (BMI) classifications that are used to assess the prevalence of overweight and obesity among Saudi children aged 6-13 years: the International Obesity Task Force (IOTF) age and gender cutoffs, the World Health Organization (WHO) growth references for school-aged children, and the Saudi (KSA) national growth references.

Methods

The sample comprised 2,169 children (52.5% girls) derived from two cross-sectional studies conducted in Riyadh and Jeddah during the 2017 and 2019 school years, respectively. Body weight and height were measured, and BMI was calculated.

Results

The proportions (%) of the participants who were classified as underweight, overweight, and obese varied according to the reference used: IOTF reference (13.8, 18.4, and 12.7), WHO reference (17.2, 19.1, and 18.9), and KSA reference (7.0, 22.4, and 9.3), respectively, indicating higher values for overweight and obesity prevalence when the WHO references were used. Kappa agreement measures between the three references were found to be high, with the coefficients ranging from 0.936 (between the IOTF and KSA references) to 0.849 (between the IOTF and WHO references). In all three classifications, girls exhibited lower overweight or obesity prevalence than boys. Family income, but not paternal or maternal education, was significantly (p = 0.015) associated with overweight/obesity when using the IOTF standards. In addition, having a small family in the house was significantly (p < 0.05) associated with obesity, irrespective of the classification system.

Conclusion

Inconsistency was observed when estimating the prevalence of underweight, overweight, and obesity among Saudi children. However, when defining the overall prevalence of overweight plus obesity among Saudi children, the IOTF classification system performed in a similar way to the KSA references (31.1% versus 31.7%) compared to the WHO references (38.0%).

Predictive value of WHO vs. IAP BMI charts for identification of metabolic risk in Indian children and adolescents

OBJECTIVES

Owing to increase in prevalence of obesity and metabolic syndrome in Indian children and adolescents, this study is conducted to assess the predictive value of IAP 2015 and WHO 2007 BMI for age cut-offs in identifying metabolic risk in Indian children.

METHODS

Cross-sectional multicentric school-based study on 9-18-year-old healthy children (n=1,418) randomly selected from three states of India.

RESULTS

WHO 2007 and IAP 2015 charts classified 222 (15.7%) and 271 (19.1%) as overweight/obese, respectively. A total of 192 (13.5%) subjects had metabolic risk. Of these 47 (25%) and 36 (18.75%) were classified as having normal body mass index (BMI) by WHO and IAP, respectively. In identifying metabolic risk, IAP 2015 and WHO 2007 charts showed a sensitivity of 81.3 and 75%, negative predictive value 96.5% as against 94.8%, positive predictive value 57.5 and 64.8%, and specificity of 89.7 and 91.6%, respectively.

CONCLUSIONS

Owing to obesity epidemic and high metabolic risk in Indians, IAP 2015 charts (as against the WHO 2007 references) which had a higher sensitivity in identifying metabolic risk may be more suitable in Indian children and adolescents.

Diagnostic performance of body mass index in detection of obesity using different cutoff points for excess body fat

OBJECTIVES

The aim of this study was to assess the diagnostic sensitivity of body mass index (BMI) in detecting obesity according to different cutoff points in order to classify a high body fat percentage (%BF) in adolescents and young adults.

METHODS

This was a cross-sectional study conducted with 2447 adolescents 18 and 19 y of age residing in São Luís, Brazil and 951 young adults 21 to 23 y of age residing in Ribeirão Preto, Brazil. Three references were used to define a high %BF (i.e., those of Williams et al., Ramírez-Vélez et al., and Macias et al.). The area under the receiver operating characteristic area under the curve (AUC) was used to assess the performance of BMI.

RESULTS

Sensitivity ranged from 38.3% to 54.1% among boys and from 12.7% to 72.7% among girls. Among young adults, it ranged from 52.3% to 67.1% in men and from 33.7% to 86.6% in women. The AUC ranged from 0.69 to 0.76 among boys, from 0.56 from 0.85 among girls, from 0.75 to 0.80 among men, and from 0.67 to 0.88 among women. The best cutoff points for the BMI were 24.79 to 25.10 kg/m² for boys, 21.89 to 27.04 kg/m² for girls, 26.43 to 28.22 kg/m² for men, and 23.34 to 29.28 kg/m² for women.

CONCLUSION

The use of different references for the classification of a high %BF implied a difference in the diagnostic sensitivity of the BMI. Higher cutoff points resulted in greater sensitivity and ability to differentiate individuals with and without obesity.