|Year : 2021 | Volume
| Issue : 3 | Page : 115-119
A proposal for the cutoff points of waist circumference values predictive of increased risk of Type 2 diabetes and hypertension in Arab adults
Naji J Aljohani1, Mohamad Maswood Ahmad2, Ashwaq Alfaqeeh2, Ahmed Bahnassi3, Nasser Alhamdan3
1 Department of Adult Endocrine, Faculty of Medicine, King Saud Bin Abdulaziz University for Health Sciences; Obesity, Endocrine and Metabolic Center, King Fahad Medical City; Prince Mutaib Chair for Biomarkers of Osteoporosis, College of Science, King Saud University, Riyadh, Saudi Arabia
2 Obesity, Endocrine and Metabolic Center, King Fahad Medical City, Riyadh, Saudi Arabia
3 Department of Adult Endocrine, Faculty of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
|Date of Submission||04-Jun-2021|
|Date of Decision||14-Jul-2021|
|Date of Acceptance||14-Jul-2021|
|Date of Web Publication||26-Aug-2021|
Dr. Naji J Aljohani
Faculty of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Riyadh 22490
Source of Support: None, Conflict of Interest: None
Introduction: Central obesity is an established risk factor for diabetes mellitus (DM) and hypertension. We aimed to identify people at the highest risk by ethnically adjusted waist circumference (WC) cutoff points. Subjects and Methods: Data were collected from a cross-sectional study of 4350 Saudi adults aged 15–64 years using a stratified, multistage, cluster random sampling. DM was based on known history or fasting blood glucose higher than 7.0 mmol/L, and hypertension was determined by having a systolic blood pressure ≥140 mmHg and/or diastolic ≥90 mmHg. WC was measured midway between the lower costal margin and iliac crest during the end-expiratory phase. Results: The mean age for all the study population was 36.6 + 13.0 years (35.6 ± 12.0 years for females; 37.5 ± 13.9 years for males). The mean WC was 95.2 + 14.01 cm for males and 89.9 + 12.6 cm for females (P < 0.001). The prevalence of diabetes was 23.8% for all subjects. The prevalence of hypertension for all subjects was 25.5%. Receiver operator characteristics curves revealed that WC cutoff points for diabetes risk are 91 cm and 97 cm for women and men, respectively, and for hypertension are 90 cm and 97 cm for women and men, respectively. Conclusions: The present study proposes the obtained cutoffs to identify those at high risk for diabetes and hypertension in the Saudi population who can be considered candidates for preventive interventions.
Keywords: Anthropometrics, diabetes, hypertension, Saudi Arabia, waist circumference
|How to cite this article:|
Aljohani NJ, Ahmad MM, Alfaqeeh A, Bahnassi A, Alhamdan N. A proposal for the cutoff points of waist circumference values predictive of increased risk of Type 2 diabetes and hypertension in Arab adults. J Diabetes Endocr Pract 2021;4:115-9
|How to cite this URL:|
Aljohani NJ, Ahmad MM, Alfaqeeh A, Bahnassi A, Alhamdan N. A proposal for the cutoff points of waist circumference values predictive of increased risk of Type 2 diabetes and hypertension in Arab adults. J Diabetes Endocr Pract [serial online] 2021 [cited 2022 Jun 28];4:115-9. Available from: https://www.jdeponline.com/text.asp?2021/4/3/115/324790
| Introduction|| |
Obesity is a worldwide health problem affecting people in different age groups and both genders. Studies in Saudi Arabia (KSA) and other Gulf Arab countries highlight the increasing burden of obesity with a reported prevalence of 13%–50% in adults. Consequently, countries from the Gulf Cooperation Council Countries also have increasing prevalence rates of diabetes mellitus (DM), with Qatar, United Arab Emirates, and Kuwait having the highest, and Saudi Arabia the lowest, as of 2012.
Obesity, more specifically central obesity, is strongly associated with metabolic syndrome (MetS), and defining central obesity with waist circumference (WC) is usually different across multiple ethnicities. Therefore, the new International Diabetes Federation (IDF) definition has proposed ethnicity-specific cutoff values for WC for European and Japanese men and women.
The IDF has recommended that more extensive investigations be performed before suitable cutoff levels are established for use in clinical practice. Nonetheless, no cutoff value was determined in our population, and we are still using the caucasian values. We have therefore conducted this study to fill this knowledge gap.
| Subjects and Methods|| |
This is a cross-sectional community-based study spanning the entire adult population of KSA conducted in 2005. We used the STEPwise approach to surveillance recommended by the WHO (STEPS) for chronic noncommunicable diseases risk factors for conducting the survey and data collection., The STEPS approach obtains core data on the established risk factors determining the significant disease burden. However, it is sufficiently flexible to allow each country to expand on the core variables and risk factors and incorporate optional modules related to local or regional interests. Essentially, the STEPS instrument covers three different levels of “steps” of risk factor assessment. Items include information for the core questions on each of the demographic and behavioral risk factors enumerated in step 1, anthropometric and clinical assessment in step 2, and biochemical assessment of lipids (triglycerides and high-density lipoprotein cholesterol levels) in step 3.
Settings and sampling strategy
Data collections included filling the questionnaire, taking the physical measurements, and conduct of biochemical measurements. A multistage stratified cluster of random sampling techniques was used to recruit the study subjects. Stratification was based on sex (male; female), age (five 10-year age groups). All health regions of Saudi Arabia (20 regions) were covered. Using the WHO STEPwise methodology,, a sample size of 196 was calculated for each of these ten strata. Primary health care centers (PHCCs) of each region were identified, and 10% of these PHCCs were randomly chosen and allocated regional samples proportionate to their catchment population in sampled PHCCs. Maps of the health center coverage areas were used to choose the houses and identify the households. Houses were assigned numbers, and a simple random draw was made.
The WHO STEPwise instrument was used. The instrument included a questionnaire and records of physical and anthropometric measurements and biochemical measurements. The questionnaire was developed by standard translation methodology (to Arabic) and back-translation (to English) by a team of bilingually fluent groups of physicians. The Arabic version was beta-tested and on 51 eligible respondents for wording and understanding of the questions. The necessary corrections were made before general use. A total of 54 male and 54 female data collectors worked in field teams; each includes four members; a male and a female data collector, a driver, and a female assistant. Data collection was supervised by a hierarchy of local supervisors, regional coordinators, and a national coordinator. All workers involved in data collection attended a comprehensive training workshop that included interview techniques, data collection tools, practical applications, and field guidelines. The team leaders reviewed the filled questionnaires before submitting them for data entry. Double entry of the questionnaires was performed using EPI-INFO 2000 software and EpiData software developed by the Menzies center for validation. After data entry, data cleaning was conducted. New variables were defined by adopting the standard STEPS variables (STEPS Data Management Manual, Draft version v1.5, October 2003World Health Organization. Geneva, Switzerland).
Analytical methods and definitions
Height, weight, and WC s were measured using the standard STEPwise approach. WC in cm was measured midway between the lower costal margin and iliac crest during the end-expiratory phase. Five milliliter of blood was collected in the morning after the participants had abstained from eating overnight. Fasting glucose was measured routinely. The diagnosis of DM was established on either (a) known case diagnosed by a health professional and is under diabetes management or (b) a fasting blood glucose ≥7.0 mmol/L. As this was an epidemiological study, screening for DM is limited to only fasting blood glucose, oral glucose tolerance tests and glycated hemoglobin were not assessed. Hypertension was diagnosed by either (a) known cases of hypertension and on treatment or (b) having a systolic blood pressure of more than 140 mmHg and/or diastolic blood pressure of more than 90 mmHg.
Data management and statistical analysis
The Statistical Package for the Social Sciences (SPSS; version 16.0, Chicago, IL, USA) was used. The receiver operator characteristics (ROC) curve of WC to predict hypertension and diabetics was used and plotted using SPSS ver. 16. The ROC curve was used to determine the appropriate cutoff points of WC in identifying those with diabetes or hypertension for all subjects, stratified according to sex. The cutoff point yielding the maximal sensitivity and specificity for predicting each risk factor was chosen. Significance was set at P < 0.05.
| Results|| |
Characteristics of the study population
The mean age for the whole study subjects was 36.6 ± 13.0 years. Men were slightly older than women (37.5 ± 13.9 years for males and females 35.6 ± 12.0 years; P < 0.001). The mean WC was 92.8 ± 13.7 cm for all subjects and it was significantly higher in males than females (95.2 ± 14.0 cm vs. 89.9 ± 12.6 cm for males and females, respectively; P < 0.001).
Prediction of diabetes risk
The prevalence of DM was 23.8% for all subjects. It was 25.3% among males, significantly higher than that among females (22.4%) (P = 0.025). The ROC curve was plotted to determine the cutoff values of WC in relation to diabetes by sex [Figure 1]. The cutoff points yield the maximal sensitivity plus specificity for predicting each diabetes and hypertension presence separately. Sensitivity and specificity using these cutoff values in diabetic men and 63% and 60%, respectively, and in diabetic women were 64% and 62%. Concerning DM, it was found that the cutoff points for DM patients were 97 cm for males and 91 cm for females [Table 1].
|Figure 1: Receiver operator characteristics for waist circumference for diabetes in males (a) and in females (b)|
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|Table 1: Proposed waist circumference cutoff points for Saudi type 2 diabetes mellitus and hypertensive patients|
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Prediction of hypertension
The prevalence of hypertension was 25.5%for all subjects. It was higher in men than women (men: 27.1% vs. women: 23.9%; P = 0.013). The ROC curves were plotted to determine the cutoff values of WC in relation to hypertension by sex [Figure 2]. The cutoff points yield the maximal sensitivity plus specificity for predicting each diabetes and hypertension presence separately. The sensitivity and specificity also using these cutoff values in hypertensive men were 63% and 61%, respectively, and in women were 65% a and 60%, respectively. For hypertension, the cutoff points for hypertensive patients were 97 cm in males and 90 cm in females [Table 1].
|Figure 2: Receiver operator characteristics for waist circumference for hypertension in males (a) and females (b)|
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| Discussion|| |
In the present study, we found that the WC predictive of diabetes was 91 cm and above for adult females and 97 cm and above for adult males. On the other hand, the WC predictive of hypertension was 90 cm and above for females and 97 cm and above for males. These cutoffs are less conservative and are way above the Europid cutoffs proposed by IDF to be used for Middle-Eastern and East-Mediterranean populations, ≥80 cm for females and ≥94 cm for males. Whether or not the proposed cutoffs will be utilized in the middle-eastern clinical setting remains to be seen, but as it is, the higher cutoffs only magnify the severity of the obesity epidemic in the region. Furthermore, the cutoffs used for the Europids are for the diagnosis of MetS, which is only a predictor of harder outcomes such as DM (as measured in the present study) and as such the higher cutoff may be expected.
The importance of central obesity as a foundation of chronic noncommunicable diseases has been emphasized by no less than IDF, giving central obesity as a prerequisite risk factor for the MetS. Previous studies from KSA also highlight the clinical use of the IDF definition in females, suggesting gender differences in MetS manifestations. Furthermore, several studies done in other regions suggest the inclusion of WC in assessing population trends of obesity.,, The present study extends the existing literature on ethnic-specific WC cutoffs for the Arab population, considering the obesity-related diseases associated with the proposed clinical cutoffs. Other factors such as the association of WC with other anthropometrics such as body mass index were previously observed in the local population and were already established, as well as its importance in the diagnosis of MetS in the Saudi population.
Furthermore, in the present study, we observed the high prevalence of DM and hypertension in the cohort. However, these results should be interpreted carefully and should not supersede recent results since data collection was done in 2005, and several epidemiologic studies pointing to a higher prevalence of DM and hypertension have already been published.,
Some limitations are noteworthy; the age of data collection may not necessarily reflect real-time trends and the cross-sectional nature of the study may limit its findings to, at best, suggestive, in terms of prevalence. Nevertheless, as the study focuses on establishing cutoffs for WC in the identification of those with DM and hypertension, the study findings are robust and worthy of further exploration. These include inclusion of other factors not covered by the STEPS such as biomarkers of obesity and DM, environmental factors such as stress, and other age-related comorbidities such as osteoporosis, variables that have already been identified as contributors to the burden of obesity-related diseases in Saudi Arabia but have yet to be investigated in large-scale studies. Adjustments for confounders such as age were not carried out and as such, while the obtained cutoffs were crude, it is nevertheless clinically useful, given that most DM cases in the study were adults and only a handful were below 18. The cutoffs were stratified for sex which is a stronger confounder since WC is sex-specific in most operational definitions of abdominal obesity. The present study is one of the largest cohorts to record WC in the Arabic population. Thus, its national scope of the study and the sample size merits its findings as relevant and generalizable.
| Conclusions|| |
The present study proposes using ethnic-specific WC predictive of diabetes and hypertension in the Saudi population. Based on the described cutoff points in this population, Arab adult females having a WC more than 90 cm and males having a WC of more than 97 cm should be considered high risk for DM and hypertension and warrants preventive interventions.
The authors would like to express their gratitude and appreciation to all the data collection, logistics, and support teams.
All authors contributed to the concept development, study conduct and data analysis/ They all participated in the drafting and revision of the manuscript and they all approved its final version.
Financial support and sponsorship
The study was supported by the Ministry of Health, Saudi Arabia.
Conflicts of interest
There are no conflicts of interest.
Compliance with ethical principles
The Saudi Ministry of Health-Center of Biomedical Ethics approved the protocol and the surveillance instrument. Informed consent of all subjects was obtained. Furthermore, data confidentiality of data was assured, and that data will be used only for the stated purpose of the survey.
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[Figure 1], [Figure 2]