The prevalence of overweight (BMI ≥ 25 kg/m2) and obesity (BMI ≥ 30 kg/m2) has been on the increase in the Gulf Arab population, primarily among children, adolescents and young adults(Reference Khatib1). In Kuwait, the overall prevalence of overweight and obesity has been found to be 30·9 and 13·9 %, respectively, among adolescents aged 10–14 years, which probably increased through the years due to the effects of modernisation, increased food consumption and sedentary lifestyles(Reference Al-Isa2, Reference Al-Isa3). The prevalence of overweight and obesity was 28·6 and 7·9 %, respectively, among Qatari adolescents(Reference Bener4), 21·5 and 13·7 % in United Arab Emirates(Reference Malik and Bakir5) and in Saudi Arabia the prevalence of obesity ranged from 33·9 % in Ha'il to 11·7 % in Jizan.
Overweight and obesity are associated with the metabolic syndrome (MS)(Reference Calcaterra, Klersy and Muratori6), even in children(Reference Druet, Baltakse and Chevenne7). The MS has been shown to be associated with a variety of morbid conditions, chief among which are CVD or type 2 diabetes mellitus (T2DM)(Reference Sartorio, Agosti and De Col8); it doubles the risk for CVD and further raises the risk for T2DM by about 5-fold(Reference Grundy9). According to the WHO, non-communicable diseases, including CVD and T2DM, were responsible for 52 % of the Eastern Mediterranean region's disease burden in 2006, and expected to rise to 60 % by 2020(10). In adults, mortality resulting from CVD is significantly higher with the MS than those not suffering from the MS(Reference Malik, Wong and Franklin11). Paediatric MS predicts significantly the MS and T2DM 25 to 30 years later(Reference Morrison, Friedman and Wang12), and predicts CVD 25 years later(Reference Morrison, Friedman and Gray-McGuire13).
Furthermore, the MS was found highly associated with increased CVD and all-cause mortality even in the absence of previous history of CVD and diabetes(Reference Lakka, Laaksonen and Lakka14), especially with the combination of elevated waist circumference, elevated glucose, either elevated blood pressure or elevated TAG, and the combination of all four of these MS individual parameters(Reference Guize, Thomas and Pannier15). Waist circumference is a simple measure by which abdominal obesity can be easily assessed, and a strong predictor of CVD risk factors in children(Reference Zimmet, Alberti and Kaufman16), and its use together with BMI has significant clinical importance for the prediction of risk factors among children and adolescents(Reference Katzmarzyk, Srinivasan and Chen17).
There are several criteria for the assessment of the MS, including the criteria produced by the WHO, the European Group for the Study of Insulin Resistance (EGIR), the National Cholesterol Education Program Third Adult Treatment Panel (ATP III) and the International Diabetes Federation (IDF)(Reference Alberti, Zimmet and Shaw18). Diagnosis of the MS requires certain risk factors, which are insulin resistance, obesity, hypertension, high TAG, reduced HDL-cholesterol level, microalbuminuria and elevated plasma glucose. The WHO considered insulin resistance as the major risk factor required for MS diagnosis. According to the EGIR, the presence of elevated plasma insulin plus other two factors (abdominal obesity, hypertension, elevated TAG, reduced HDL-cholesterol or elevated plasma glucose) constitutes a diagnosis of the MS. National Cholesterol Education Program ATP III criteria establishes the diagnosis by the presence of three of five factors of the MS and there is no single factor required for this diagnosis(Reference Cook, Weitzman and Auinger19). The IDF considers the presence of abdominal obesity as the main factor, with two additional risk factors to be sufficient for MS diagnosis(Reference Grundy, Cleeman and Daniels20).
Until now, there is no information on the prevalence of the MS in the Arabian Gulf countries among adolescents. The present study attempted to assess the prevalence of the MS among female Kuwaiti adolescents, and to compare the effectiveness of the IDF and the modified ATP III diagnostic criteria for identifying the MS, since there are no specific Arab diagnostic criteria for the MS.
Methods
Sample
A cross-sectional sample of apparently healthy female Kuwaiti school students aged 10–19 years was used for the study, adapting a multistage cluster sample. Out of six governorates in Kuwait, two governorates were randomly selected for the present study (Capital and Hawally). We obtained the list of all intermediate and secondary public schools in these two governorates from the Ministry of Education. From the list we randomly chose four schools, one intermediate and one secondary from each of the governorate. Every student in each of these four selected schools was invited to participate. Students suffering from diabetes mellitus, hypertension, cardiac diseases, renal diseases, epilepsy, students receiving medications, and those with broken legs (with cast), for the sake of weight measurement, were excluded. We obtained written informed consent from the parent or guardian of all the participants. The final sample included 431 female students, almost all of them Kuwaiti nationals, in the age group of 10–19 years.
Questionnaire and measurements
Sociodemographic and health-related information was obtained through a questionnaire. Ethical approval was taken by the local Ethics Committee in the Faculty of Medicine of Kuwait University. The subjects were examined in the morning after at least a 10 h overnight fast. Blood pressure was measured with a standard gauge mercurial sphygmomanometer after the subject had been seated, and waist circumference was measured by using measuring tape, midway between the inferior margin of the ribs and the superior border of the iliac crest. All measurements were taken by the same investigator to avoid inter-observer variations. Fasting blood samples were collected via venepuncture and kept cooled in an ice box until separation in a refrigerated centrifuge, then the resulted plasma and serum samples were stored frozen at − 80°C until analyses were performed. HDL, TAG and glucose were analysed by a Beckman Chemistry Analyser (Beckman Corp., Fullerton, CA, USA). All statistical analyses were done using SPSS statistical software (version 16; SPSS, Inc., Chicago, IL, USA).
Definition of the metabolic syndrome criteria used
Five parameters are used by both the IDF and the ATP III modified for age. According to the IDF criteria, the MS is diagnosed by the presence of high waist circumference plus two other parameters with cut-off values related to age; the cut-off points used are shown in Table 1 (Reference Alberti, Zimmet and Shaw18). According to the modified ATP III criteria, the MS is diagnosed when individuals meet at least three of the listed criteria in Table 1, using data from the American Third National Health and Nutrition Examination Survey (NHANES III) with no data for Arabs.
Table 1 Cut-off points of International Diabetes Federation (IDF) and Third Adult Treatment Panel (ATP III) criteria
* ATP criteria for the metabolic syndrome identified as the presence of three or more of the listed factors.
† IDF criteria for the metabolic syndrome identified as the presence of high waist circumference plus two or more of the listed factors.
Statistical methods
Data entry and analysis were carried out using SPSS version 16 (SPSS, Inc.). In addition to descriptive statistics such as mean, standard deviation and proportions, we used sensitivity and specificity measures to assess the diagnostic accuracy of the two different MS criteria.
Results
The mean age was 14·8 (sd 2·2) years (Table 2). Anthropometric measures in the female participants are also shown in Table 2. Table 3 shows the results for waist circumference, TAG, HDL, fasting blood glucose, systolic blood pressure and diastolic blood pressure. According to the IDF criteria, waist circumference, TAG, fasting blood glucose and blood pressure were increased among the subjects, while HDL was decreased, same as using the modified ATP III criteria. Table 4 shows the relationship between the IDF and the modified ATP III criteria; the sensitivity of the IDF for the ATP criteria was 73 %, while the specificity was 90·4 %. The positive predictive value of the IDF was 0·415, while the negative predictive value was 0·027. If a student has the MS by the IDF, there is a 41·5 % chance of having the MS by the ATP criteria, while 2·7 % of those not having the MS by the IDF actually have the MS by the modified ATP criteria.
Table 2 Age and anthropometric measures in the female participants (n 439)
(Mean values and standard deviations)
Table 3 Metabolic syndrome (MS) prevalence difference between International Diabetes Federation (IDF) and Third Adult Treatment Panel (ATP III) criteria in female students
Table 4 Sensitivity and specificity of International Diabetes Federation (IDF) and modified Third Adult Treatment Panel (ATP III) metabolic syndrome (MS) diagnostic criteria
Discussion
Both developed and developing countries are currently expected to be suffering from the MS pandemic, especially among children and adolescents, because the prevalence of the MS increases progressively with weight status, which increases with increasing BMI values(Reference Calcaterra, Klersy and Muratori21, Reference Ryu, Kweon and Park22). Obese patients have a three-fold increased risk of developing the MS with respect to overweight patients(Reference Calcaterra, Klersy and Muratori21). The present study found that the prevalence of the MS among female Kuwaiti adolescents was 14·8 and 9·1 %, according to the IDF and ATP III, respectively, which is high. Worldwide, the prevalence of the MS among female adolescents in the USA for the period 1999–2004 was approximately 2·1 % using the IDF criteria(Reference Ford, Li and Zhao23), 2·5 % among female Chinese adolescents aged 14–16 years, using the ATP III criteria(Reference Xu and Ji24), ranging between 5·1 % in 1998 and 4·9 % in 2001 among female Korean adolescents using the ATP III criteria(Reference Lim, Jang and Park25), and 9·9 % among Iranian females, using the ATP III criteria(Reference Esmaillzadeh, Mirmiran and Azadbakht26). Among 248 Caucasian females in Italy, the prevalence of the MS is increased with the advance of pubertal stage from 19·2 % early mid-pubertal stage to 28·9 % late pubertal stage(Reference Sartorio, Agosti and De Col8). According to the ATP III criteria, out of 1393 Korean students, aged 12–13 years, the prevalence of the MS was 1·6 % for normal-weight and 22·3 % for overweight students(Reference Ryu, Kweon and Park22). The overall prevalence of the MS among adolescents in Canada was 9·6 % using the IDF adolescent criteria and 7·6 % using the modified ATP III criteria(Reference Jolliffe and Janssen27), and 2·2 % among Turkish adolescents using the modified ATP III criteria(Reference Agirbasli, Cakir and Ozme28). The prevalence differs with respect to sex. In a study done on 506 students under the age of 19 years, it was found that the MS was higher among obese (39·1 %) than among overweight (2·8 %) and normal-weight (0·3 %) students(Reference Vissers, Vanroy and De Meulenaere29). Furthermore, it was found that MS prevalence among sixty overweight Indian adolescents was 36·6 %(Reference Singh, Bhansali and Sialy30). In a large study done on 20 000 Chinese children (aged 6–18 years), the prevalence of the MS was 0·9, 7·6 and 29·8 % in the normal-weight, overweight and obese children, respectively(Reference Wan, Mi and Wang31).
These criteria, IDF and ATP III, have not been made for the Arab population. Even some studies among adult Arabs showed different cut-off points, as one study among Kuwaiti subjects aged between 18 and < 50 years used waist circumference scores>90 cm for females as high scores(Reference Al-Shayji and Akanji32). Another community-based study for rural adults in Iraq found that optimal cut-off points for waist circumference for the diagnosis of the MS among the rural Iraqi adult population was 99 cm in women(Reference Mansour, Al-Hassan and Al-Jazairi33). Studies are needed to set cut-off values for waist circumference for the diagnosis of the MS for use among adolescents of the Arab population instead of European values as in the IDF criteria, or of American values as in the ATP III criteria.
Since childhood MS and obesity persist into adulthood, early identification helps target interventions to improve future cardiovascular health(Reference Ryu, Kweon and Park22). It can be concluded that there has been a high prevalence of the MS (>10 %) among Kuwaiti adolescents, whichever criteria are used, which indicates an urgent need for intervention programmes to prevent increased prevalence of CVD and T2DM. Furthermore, the modified ATP III criteria tend to give lower values for the prevalence of the MS in comparison with the IDF criteria (9·1 v. 14·8 %), and neither has specific criteria for Arabs, which indicates the need for MS diagnostic criteria specific for the Arab population.
Our findings, however, should be understood in the light of a number of limitations. Although the present study is one of the first studies of this nature in a society where obesity in the adolescent has been shown to be rapidly increasing, our findings have several limitations. First, the generalisation of the results may be reasonable but two governorates we have chosen may be slightly more urban than some other governorates in Kuwait. As such, it is possible that our estimates may be slightly biased. There were other limitations such as lower rates of parental and/or students' consent to take part in the study. Higher refusal rate is a concern, particularly in terms of selection bias, if the refusal rates vary with different strata of the population. For instance, if the richer parents refused more frequently than poorer parents or less educated parents were more overprotective than more educated ones there is a possibility of selection bias although it is difficult to ascertain which way such a bias would have affected our estimates. Fasting of the students could also be not controlled and as such blood measurements may not be easily generalised.
Acknowledgements
The authors are grateful to Kuwait University Research Administration and Kuwait Foundation for the Advancement of Science (KFAS) for granting the present study (MC 01/04). They are also grateful to all participating adolescents, their parents, and to directors of selected schools for facilitating data collection.
A. A.-I., L. T. and A. O. A. designed the study and wrote the manuscript, supervised the data collection and analysis in addition to writing the manuscript together.
There are no conflicts of interest.
