Waist circumference and waist:height ratio percentiles using LMS method in Chilean population

Evidence for central obesity risk-related thresholds for adolescents aged 11 to 18 years in England using the LMS method

INTRODUCTION

Central obesity has been shown to better indicate health risks compared to general obesity. Measures of central obesity include waist-to-height ratio (WHtR), waist-to-hip ratio (WHR) and waist circumference (WC). The National Institute of Health and Care Excellence (NICE) recently recommended the use of WHtR alongside body mass index (BMI) to identify risks in adults and children, whilst recognising the need for more evidence relating to WHtR in children. This study explores risk thresholds for central obesity measures throughout adolescence. It compares these with those currently recommended in England and discusses whether these thresholds are age- and sex-specific.

METHODS

Data on adolescents aged 11 to 18 years from the Health Survey for England (HSE) during 2005 to 2014 was used to calculate WHtR, WHR and WC percentiles. Next, smoothed lambda-mu-sigma (LMS) curves were created and the percentiles which align with the adult thresholds at age 18 years identified. This allows the most appropriate risk related thresholds for each measure during adolescence to be determined.

RESULTS

WHtR LMS curves are stable and flat throughout adolescence. WHR decreases in girls and WC increases in both boys and girls, during adolescence. Across all measures, there is slightly more fluctuation in higher percentiles, and in girls' WHR.

DISCUSSION

In practice, WHtR thresholds are simple to use to identify central obesity related risks. In particular, they are recommended because the same thresholds can be used for males and females and for adolescents and adults. The results support NICE guidance to use WHtR thresholds alongside BMI thresholds to identify individual risk.

IMPLICATIONS AND CONTRIBUTION

This study uses central obesity measures, including waist-to-height and waist-to-hip ratios, to investigate risk-related thresholds for adolescents. It is the first to do so using English data. It provides support for current NICE recommendations to use adult waist-to-height thresholds in adults and children, alongside BMI measures in clinical and non-clinical settings.

Diagnosis accuracy of waist-to-height ratio to predict cardiometabolic risk in children with obesity

BACKGROUND

Waist-to-height ratio (WHtR) predicts abdominal fat and cardiometabolic risk. In children with obesity, the most adequate cut-off to predict cardiometabolic risk as well as its ability to predict risk changes over time has not been tested. Our aim was to define an appropriate WHtR cut-off to predict cardiometabolic risk in children with obesity, and to analyze its ability to predict changes in cardiometabolic risk over time.

METHODS

This is an observational prospective study secondary to the OBEMAT2.0 trial. We included data from 218 participants (8-15 years) who attended baseline and final visits (12 months later). The main outcome measure was a cardiometabolic risk score derived from blood pressure, lipoproteins, and HOMA index of insulin resistance.

RESULTS

The optimal cut-off to predict the cardiometabolic risk score was WHtR ≥0.55 with an area under the curve of 0.675 (95% CI: 0.589-0.760) at baseline and 0.682 (95% CI: 0.585-0.779) at the final visit. Multivariate models for repeated measures showed that changes in cardiometabolic risk were significantly associated with changes in WHtR.

CONCLUSION

This study confirms the clinical utility of WHtR to predict changes in cardiometabolic risk over time in children with obesity. The most accurate cut-off to predict cardiometabolic risk in children with obesity was WHtR ≥0.55.

IMPACT

In children, there is no consensus on a unique WHtR cut-off to predict cardiometabolic risk. The present work provides sufficient evidence to support the use of the 0.55 boundary. We have a large sample of children with obesity, with whom we compared the previously proposed boundaries according to cardiometabolic risk, and we found the optimal WHtR cut-off to predict it. We also analyzed if a reduction in the WHtR was associated with an improvement in their cardiometabolic profile.

Interplay between rotational work shift and high altitude-related chronic intermittent hypobaric hypoxia on cardiovascular health and sleep quality in Chilean miners

Mining activities expose workers to diverse working conditions, rotational shifts and high altitude-related hypobaric hypoxia. Separately, each condition has been reported having a negative impact on miners' health risk; however, the combination of both stressors has been poorly explored. The present study aimed to analyse the effects of exposure to rotational work shift (RWS) alone or in combination with high altitude-related chronic intermittent hypobaric hypoxia (CIHH) on cardiometabolic, physical activity and sleep quality related markers in copper miners from Los Pelambres mine in Chile. One hundred and eleven male miners working in RWS with or without CIHH were included. Anthropometrics measures, sleep quality assessment, physical activity level (PAL) and handgrip strength were evaluated. Exposure to CIHH exacerbated the detrimental effects of RWS as miners exposed to the combination of RWS and CIHH where more obese and had a wider neck circumference, reduced PAL at work and worsened sleep quality. Practitioner summary: The purpose was to assess cardiometabolic health and sleep quality markers associated with the combined effects of rotational shift work and high altitude-related intermittent hypobaric hypoxia in miners. Findings showed a wider neck circumference, lower physical activity level and higher prevalence of poor sleep quality in exposed miners. Abbreviations: ANOVA: analysis of variance; BM: body mass; BMI: body mass index; CI: confidence intervals; CIHH: chronic intermittent hypobaric hypoxia; CV: cardiovascular; CVR: cardiovascular risk; HA: high altitude; HACE: high-altitude cerebral edema; HGS: handgrip strength; IPAQ-SF: International Physical Activity Questionnaire - Short Form; LSD: Fisher's least standardized difference; MANCOVA: multivariate general lineal model; MET: metabolic equivalent; PAL: physical activity level; PSQI: Pittsburg sleep quality index; RWS: rotational work shift; WHR: waist-to-hip ratio.

Is waist-to-height ratio a better predictor of hypertension and type 2 diabetes than body mass index and waist circumference in the Chilean population?

OBJECTIVE

The aim of this study was to identify which anthropometric measurement (body mass index [BMI], waist circumference [WC], or waist-to-height ratio [WHtR]) is a better predictor of type 2 diabetes and hypertension in the Chilean population.

METHODS

The study included 13 044 participants (59.7% women) from the Chilean National Health Surveys conducted in 2003, 2009-2010, and 2016-2017. BMI, WC, and WHtR were the anthropometric measurements evaluated. Hypertension was defined as systolic blood pressure ≥140 mm Hg and diastolic blood pressure ≥90 mm Hg or on medication for hypertension. Diabetes was defined as fasting glucose ≥7 mmol/L or on medication for diabetes. The receiver operating characteristics (ROC) curve and the area under curve (AUC) were computed to derive the specificity and sensitivity using a bootstrapping approach.

RESULTS

Compared with BMI and WC, WHtR was the anthropometric measurement with the highest AUC curve in both sexes for hypertension (AUC for women: 0.70; 95% confidence interval [CI], 0.67-0.73; AUC for men: 0.71; 95% CI, 0.69-0.74) and diabetes (AUC for women: 0.71; 95% CI, 0.66-0.77; AUC for men: 0.71; 95% CI, 0.67-0.76). The sex-specific cutoff points of WHtR to predict hypertension were 0.59 and 0.55 for women and men, respectively. Those used to predict diabetes were 0.60 and 0.58 for women and men, respectively.

CONCLUSION

WHtR was a better predictor of hypertension and diabetes than BMI and WC in Chile. The definition of cutoff points specific for the Chilean population could be implemented in future screening programs aiming to identify high-risk individuals.