30-year cross-sectional trends in waist-to-height ratio in Australian school age children; 1985 to 2015

Prevalence of Thinness, Overweight, Obesity, and Central Obesity in Finnish School-Aged Children: A Comparison of National and International Reference Values

INTRODUCTION

The global epidemic of obesity concerns children, and monitoring the prevalence is of highest priority. Body mass index (BMI) with age- and sex-specific cutoff values determines weight status in children, although multiple reference systems exist. Our aim was to compare the prevalence for thinness, normal weight, overweight, and obesity in Finnish school-aged children according to national and international reference values, as well as to determine which cutoff values for overweight agree with the criteria for central obesity.

METHODS

This study includes 10,646 children aged 9-12 years from the Finnish Health in Teens cohort. Height, weight, and waist circumference were measured in 2011-2014. BMI (weight [kg]/height [m]2) and the waist-to-height ratio (WHtR; waist [cm]/height [cm]) were calculated. The WHtR cutoff of >0.5 indicated central obesity. We compared the sex-specific prevalence of thinness, overweight, and obesity using the International Obesity Task Force (IOTF), World Health Organization (WHO) and Finnish (FIN) BMI-for-age reference values, as well as these three against central obesity based on the WHtR.

RESULTS

The prevalence of thinness, overweight, and obesity were 11.0%, 12.7%, and 2.6%, respectively, using IOTF; 2.6%, 15.9%, and 5.2% using WHO; and 5.1%, 11.4%, and 2.2% using FIN. Overweight and obesity were more common in boys than girls using WHO and FIN, while thinness was more common in girls using IOTF and FIN. IOTF versus WHO exhibited moderate agreement (κ = 0.59), which improved for IOTF versus FIN (κ = 0.74). Of those classified as overweight by WHO, 37% and 47% were regarded as normal weight according to IOTF and FIN, respectively. The prevalence of central obesity was 8.7%, and it was more common in boys than girls. WHO provided the highest sensitivity: 95% of individuals with central obesity were classified with overweight or obesity. Using FIN provided the highest specificity (93%).

CONCLUSION

Our findings show that WHO overestimates the prevalence of overweight and obesity, while IOTF overrates thinness. Thus, comparing prevalence rates between studies requires caution. The novelty of this study is the comparison of the cutoff values for overweight with central obesity. The choice of reference system affects the generalizability of the research results.

Estimating trunk fat in children according to sex using basic somatic readings: an opportunity for improving evaluation among girls

BACKGROUND

The fat mass estimators waist-to-height ratio (WHtR) and relative fat mass-pediatric (RFMp) complement the widely accepted body mass index (BMI) in obesity evaluation.

AIMS OF THE STUDY

Conduct an easy appraisal of trunk fat and the cardiometabolic risk associated with pediatric obesity.

METHODS

A total of 472 children (39% boys in the total sample) were classified as underweight, normal weight, overweight or obese (nutritional groups, NGs) according to BMI Z-score after initial anthropometric data were obtained and ad hoc exclusion criteria were applied. WHtR and RFMp (% of total fat) were calculated for each group, associations were assessed through multiple linear regression (MLR), and differences between sexes were evaluated (medians, IQR).

RESULTS

The mean age (mean (95% CI)) was 10.8 y (10.1-11.1). The values in the total sample were as follows: WHtR, 0.5 (0.49-0.51) and RFMp%, 32.3 (31.7-33.0). In the overweight group, the values were as follows: WHtR, 0.51 (0.50-0.52) and RFMp(%), 34.2 (33.3-35.1). In the obese group, the values were as follows: WHtR, 0.56 (0.55-0.57) and RFMp(%), 37.8 (36.9-38.6). The associations were as follows (NG; independent variables): In the NG, adjusted R2 values were between 0.74 and 0.78. In the total sample, the beta coefficient was 3.36 (P < 0.001) for RFMp for girls; for waist circumference (WC), the beta coefficient was 2.97 (P < 0.001), and for WHtR the beta coefficients were - 0.01 (p < 0.001) and 0.03 (p < 0.001),for girls and for WC respectively. The sex differences were as follows: BMI exhibited no differences in the NG (Mann-Whitney U). WHtR (median (IQR)) differed (M vs. F) in the total sample (0.49 (0.45-0.54) vs. 0.52 (0.45-0.56), p < 0.004); in the overweight group (0.51 (0.48-0.53) vs. 0.54 (0.51-0.55), p < 0.001); and in the obese group (0.55 (0.52-0.57) vs. 0.57 (0.54-0.60), p < 0.004). RFMp (%) differed in the total group (29.21 (24.27-32.92) vs. 36.63 (30.2-39.51), p < 0.001); in the overweight group (31.24 (28.35-32.35) vs. 37.95 (35.75-38.82), p < 0.001) and in the obese group (35.89 (32.05-36.15) vs. 40.63 (38.27-42.42), p < 0.001).

CONCLUSIONS

WHtR and RFMp are simple and reliable indices that do not require centile charts. Their values, including waist circumference, can be used to estimate the different trunk fat components in boys and girls better than BMI, especially if individuals are overweight or obese. RFMp proved to be more reliable as it considers sex. Both should be included in routine anthropometric readings.

Waist circumference-to-height ratio and body mass index for obesity classification in Irish children

AIM

Waist circumference-to-height ratio (WHt) has been proposed as an alternative measure to BMI due to its focus on central weight distribution and its basic threshold for increased cardiometabolic risk. This study aimed to compare prevalence of overweight including obesity using BMI and WHt, and assess 10-year trends of WHt prevalence, in a representative sample of Irish children.

METHODS

Children measured during rounds 2-5 of the Childhood Obesity Surveillance Initiative (n = 20037) were classified as healthy weight or overweight including obesity (International Obesity Task Force age and sex BMI cut-offs), and low or high WHt (WHt ≥ 0.5). Differences in prevalence of BMI and WHt classifications were determined for round five in younger (<9 years) and older (≥9 years) children. The prevalence of high WHt was assessed across rounds.

RESULTS

Differences in prevalence between overweight including obesity and high WHt were apparent in younger (BMI: 16.7%, WHt: 8.9%; p < .001) and older (BMI: 21.3%, WHt: 12.1%; p < .001) children. An inverse trend for prevalence of high WHt was identified across rounds (p < .001).

CONCLUSION

BMI overestimates overweight including obesity prevalence compared to WHt. Given its ease of use, consideration of the WHt as an additional measure in childhood surveillance and screening is warranted.

Trends in abdominal obesity among Chinese children and adolescents, 1993-2015

OBJECTIVES

The prevalence of general overweight and obesity defined by body mass index criteria has greatly increased in Chinese children and adolescents in recent decades. However, few studies have considered the trend in abdominal obesity in Chinese children and adolescents. This study aimed to examine the secular trends in waist circumference (WC), waist-to-height ratio (WHtR) and the prevalence of abdominal obesity among Chinese children and adolescents aged 6-17 years from 1993 to 2015.

METHODS

A total of 11,985 children and adolescents aged 6-17 years participated in the China Health and Nutrition Survey, a continuous cross-sectional survey, conducted from 1993 to 2015. Abdominal obesity was defined as WC≥age- and sex-specific 90th percentile based on the reference from Chinese children and adolescents or WHtR≥0.50.

RESULTS

After adjustment for age, sex and region, mean WC increased from 60.27 cm in 1993 to 64.31 cm in 2015 (p for trend <0.001), and mean WHtR increased from 0.430 to 0.434 (p for trend <0.05). The prevalence of abdominal obesity defined by WC reference increased from 5.0% in 1993 to 19.3% in 2015 and defined by WHtR reference increased from 6.4% in 1993 to 14.5% in 2015 (p for trend <0.001).

CONCLUSIONS

The prevalence of abdominal obesity among Chinese children and adolescents aged 6-17 years has increased between 1993 and 2015.

Global, regional and time-trend prevalence of central obesity: a systematic review and meta-analysis of 13.2 million subjects

We aimed to examine the global prevalences of central obesity according to age, sex, race, place of residence, geographical region, national income level, and the definitions of central obesity. MEDLINE and Embase were searched. Studies with sample size of ≥ 500 and investigated individuals aged ≥ 15 years were included. Metaprop (a Stata command) was adopted to conduct a meta-analysis of prevalence, and the Freeman-Tukey Double Arcsine Transformation was used to stabilize the variances. A random-effects model was used to evaluate the prevalence and 95% confidence intervals (CI) of central obesity. There were 288 studies involving 13,233,675 individuals in this analysis. The overall prevalence of central obesity was 41.5% (95% CI 39.9–43.2%). A higher prevalence was found in older individuals, female subjects, urban residents, Caucasians, and populations of higher income level countries. Regarding regional variations, the highest prevalence was found in Sothern America (55.1%, 95% CI 45.8–64.3%) and Central American (52.9%, 95% CI 32.7–72.7%). Its prevalence was rapidly rising from 1985 to 2014. From 1985–1999 to 2010–2014, younger subjects aged 15–40 years showed a more drastic rise in prevalence (16.3 to 33.9%) than subjects aged > 40 years (43.6 to 57.9%). Male individuals have a more drastic rise (25.3 to 41.6%) than females (38.6 to 49.7%). Major increasing in prevalence of the condition in the past three decades, particularly in certain subgroups. These findings could act as a useful reference to inform public health strategies to minimize the impact of central obesity on population health.