Applied nutritional investigationWaist-to-height ratio: An accurate anthropometric index of abdominal adiposity and a predictor of high HOMA-IR values in nondialyzed chronic kidney disease patients
Introduction
The increasing prevalence of overweight and obesity is reaching global epidemic status [1]. Considerable evidence supports the role of obesity and abdominal fat depots in the pathogenesis and development of metabolic disorders and risk factors for chronic diseases [2], [3]. Abdominal adiposity (AbAd) is now recognized as a better predictor of cardiovascular disease (CVD) risk than global adiposity [4], [5]. Moreover, AbAd is itself a determinant of altered insulin sensitivity and insulin resistance (IR), which in turn is a condition associated with hypertension and dyslipidemia, and has been considered an independent predictor of CVD in the general population [3], [6], [7], [8]. Additionally, high total and central adiposity are related to an increased prevalence of diabetes mellitus, hypertension, and CVD [2], [3], [9], which are directly correlated to chronic kidney disease (CKD) [10], [11].
CKD is a public health problem in the general population [12], and in early stages is associated with metabolic and clinical disorders including IR, dyslipidemia, and coronary heart disease. Patients with mild to moderate CKD are likely to present IR [13], which leads to nutritional, metabolic, and cardiovascular complications [14]. IR is recognized as a risk factor for CVD in nondialyzed patients with CKD [15], [16], [17].
Recent studies report that overweight and obesity are the most common nutritional conditions in nondialyzed patients with CKD that contribute to the high prevalence of IR and CVD [18], [19], [20], [21]. Considering that CKD and obesity are associated with increased risk for CVD, it is feasible to hypothesize that when occurring together they may worsen the prognosis. Therefore, the early recognition of modifiable risk factors associated with CVD, such as AbAd and IR, may improve CKD prognosis and treatment approach [22], [23].
The evaluation of body adiposity and AbAd depots counts with many useful methods. Among reliable and sophisticated methods are hydrostatic weighing, dual-energy x-ray absorptiometry (DXA), computed tomography, and magnetic resonance imaging. However, such methods are complex, time-consuming, and costly, hindering their use in clinical settings [24], [25]. Alternative methods to overcome these barriers, based on anthropometric measures, are recommended, but their accuracies need to be evaluated. Waist circumference (WC) and waist-to-hip ratio (WHR) are the most commonly used anthropometric methods to assess AbAd in individuals and groups, showing high correlation with more sophisticated methods [26], [27]. In patients with CKD, the evaluation of the accuracy of AbAd indexes are limited and mostly performed in dialysis settings [28], [29], [30]. More recently, the ratio between waist and height (WheiR) has been demonstrated as a better index associated with CKD compared with body mass index (BMI) [31].
The ability of BMI, WC, WHR, and WheiR to determine major CVD risk factors has largely been based on receiver-operating characteristic (ROC) curve analysis [32], [33]. WheiR is strongly associated with different CVD risk factors in population-based studies conducted in China [34], Taiwan [35], and Brazil [36]. These studies identified the best cutoff points for WheiR as a discriminator for high coronary risk, suggesting its use in population studies. To our knowledge, there has been no report to date attempting to identify the most appropriate cutoff point of these indices of AbAd with discriminatory capability for IR in nondialyzed patients with CKD. Therefore, studies focusing on this topic might improve evaluation of AbAd and might help to apply more effective therapeutic strategies to reduce obesity-associated morbidity and mortality in these patients.
Section snippets
Objectives
The aim of this study was to evaluate the correlation between anthropometric parameters, used in clinical settings to estimate AbAd, with trunk fat mass estimated by DXA, as reference method in nondialyzed patients with CKD. As a secondary objective, we determined the association between AbAd with homeostasis model assessment index of insulin resistance (HOMA-IR), glucose, and triglycerides (TG) values and the cutoff point for AbAd to predict high HOMA-IR values in these patients.
Study design and population selection
This is an observational, cross-sectional study. Clinically stable nondialyzed patients with CKD, older than age 18 y, with an estimated glomerular filtration rate (eGFR) < 60 mL/min, were enrolled between August 2008 and July 2010. Exclusion criteria included the presence of apparent edema, active malignant diseases, acute inflammation, and use of immunosuppressive drugs. The nutritional recommendations for all patients followed the international guidelines for CKD treatment [10], [37]. These
Results
One hundred and thirty-four patients with CKD (55% men) were under regular treatment with nephrologists for 4.9 ± 3.2 y and with dietitians for 3.3 ± 2.0 y, respectively. Mean age was 64.9 ± 12.5 y and eGFR was 29.0 ± 12.7 mL/min. CKD stage distribution was as follows: 10.4% (n = 14) in stage 3a (eGFR = 50.05 ± 4.1), 35.8% (n = 48) in stage 3b (eGFR = 37.6 ± 4.08 mL/min), 35.8% (n = 48) in stage 4 (eGFR = 22.6 ± 4.4 mL/min), and 17.9% (n = 24) in stage 5 (eGFR = 11.7 ± 2.4 mL/min). Laboratory
Discussion
In the present study, the precision of different anthropometric measures of AbAd was evaluated in nondialyzed patients with CKD, using DXA trunk fat depots as a reference method. The efficacy of AbAd indexes for predicting high HOMA-IR values also was determined.
The studied patients showed no protein–energy malnutrition; on the other hand, overweight/obesity was the prevalent condition, similar to the obesity epidemic worldwide, observed also in Brazil and Asian countries [45], [46]. High body
Conclusion
In conclusion, the present results show consistent evidence for the use of WheiR as an index for evaluating AbAd, in nondialyzed patients with CKD because of its particularly strong correlation with DXA trunk fat, independent of BMI and with no differences between men and women. The cutoff value for WheiR ≥ 0.55 was identified as a substantial predictor of high HOMA-IR values.
Acknowledgments
This study was supported by Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ).
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Cited by (0)
MIBS was responsible for the conception and design of the study; assembly, analysis and interpretation of data; drafting of the manuscript; and approval of the final version of the manuscript. CCSL was responsible for the generation, collection, and assembly of data; and approval of the manuscript final version of the manuscript. MRSGT was involved in the analysis and interpretation of the data; revision of the manuscript; and the approval of the final version of the manuscript. RB was involved in the conception and design of the study and approval of the final version of the manuscript.
The authors have no conflicts of interest to declare.