The name of metabolic syndrome has been considered for the clustering of some cardiovascular risk factors from 1988 [
This study analyzed data from a cross sectional study (Healthy Heart study), conducted by the Zanjan University of medical sciences between 2002 and 2003 in Zanjan, the capital of the Iranian province of the same name. The main ethnic groups living in the province are Azeries (Turks) and Kurds.
In the original study the anthropometric parameters, nutritional status and cardiovascular risk factors in the population of Zanjan was assessed. A stratified, multistage random sampling was used and a total of 4000 subjects aged more than 15 years were enrolled in the study. We excluded 723 subjects for whom some information was missing and 336 people aged less than 20 years. The remaining subjects were 2941 subjects including 1396 men and 1545 women. Subjects completed a questionnaire which included dietary habits, past medical history, smoking status, physical activity, and educational levels.
All the subjects received oral information concerning the study and gave their written consent. The study was approved by the Ethical Committee of Zanjan University of medical sciences.
In the original study Waist circumferences between the lowest rib and the iliac crest at the level of umbilicus were measured in duplicate to the nearest mm with flexible tape.
Blood pressure was measured sitting with a random zero sphygmomanometer. Systolic (Korotkoff phase I) and diastolic (Korotkoff phase V) blood pressure was measured twice on the left upper arm and the average used for analysis. Average systolic blood pressure more than 130 mmHg or diastolic blood pressure more than 85 mmHg or current use of antihypertensive medications was defined as hypertension.
Laboratory measurements were done at the laboratory of Zanjan University of medical sciences, Valie-e-sasr Hospital. Plasma glucose was measured by the glucose-peroxidase colorimetric enzymatic method with a sensitivity of 5 mg/dl and intra-assay coefficients of variation (CV) I.7% in lower limit and 1.4% in upper limit concentrations. Inter-assay CV for the assay was 1.1% in lower limit and 0.6% in upper limit concentrations. Fasting plasma glucose (FPG) more than 100 mg/dl was defined abnormal in this study.
Serum Cholesterol and Triglyceride of all the participants were measured after 12–14 hours of fasting with colorimetric method with a sensitivity of 5 mg/dl. Intra-assay and inter-assay CV for the assay was 1.6% and 1.1% in lower limit and 0.6% and 0.9% for upper limit concentrations respectively. High-density lipoprotein cholesterol (HDL-C) was measured after precipitation of the apolipoprotein B-containing lipoproteins with phosphotungstic acid (Pars azmoon kit, Iran).
Hypertriglyceridemia was defined as triglyceride (TG) concentration more than 150 mg/dl. HDL Cholesterol less than 50 mg/dl in females and less than 40 mg/dl in males was considered to be abnormal.
In this study, subjects with three or more of the following five risk factors of the criteria of the modified NCEP III were defined as having metabolic syndrome: (1) triglycerides
The data are presented as frequencies, percentages, and 95% confidence intervals. The prevalence of different abnormalities was compared using
The prevalence of the metabolic syndrome in the study population was 23.7% (CI 95%:22% to 25%,
Prevalence of individual abnormalities of the metabolic syndrome by age in urban population of Zanjan, Iran. Numbers in parentheses are percent. FPG; fasting plasma glucose, TG; triglyceride, HDL; high density lipoprotein, WC; weist circumference High TG: TG > 150 mg/dl, Low HDL: HDL < 50 in female and <40 mg/dl in male, High WC: WC ≥ 88 cm in female and ≥102 cm in male, High BP: BP ≥ 130/85 mmHg.
Age groups (years) | High TG | Low HDL | High WC | High BP | |
---|---|---|---|---|---|
Men ( | |||||
20–29 | |||||
30–39 | |||||
40–49 | |||||
50–59 | |||||
+60 | |||||
Total | |||||
Women ( | |||||
20–29 | |||||
30–39 | |||||
40–49 | |||||
50–59 | |||||
+60 | |||||
Total |
Low HDL-C was the most common metabolic abnormality in both sexes. Mean serum HDL-C was
Table
Comparison between subjects with metabolic syndrome and normal people for the mean value of atherosclerosis risk factors. BMI, body mass index; WC, Waist circumference; BP, Blood pressure; LDL, low density lipoprotein; HDL, high density lipoprotein.
Variables | Men ( | Women ( | ||||
Norma | Metabolic syndrome ( | Normal ( | Metabolic syndrome ( | |||
BMI (kg/m2) | 22.5 ± 3.8 | 26.4 ± 4.2 | 0.00 | 23 ± 4.2 | 28.5 ± 4.4 | 0.00 |
WC (Cm) | 80.5 ± 10.7 | 94.2 ± 11 | 0.00 | 76.8 ± 9.8 | 93.2 ± 10.7 | 0.00 |
BP (mmHg) | 0.00 | 0.00 | ||||
Systolic | 112 ± 9.4 | 140 ± 21.9 | 108.5 ± 9.8 | 139.7 ± 23 | ||
Diastolic | 73.2 ± 8.1 | 86.2 ± 12 | 72.3 ± 8.4 | 87 ± 12.7 | ||
LDL-C (mg/dl) | 99.3 ± 30.5 | 123.6 ± 37.7 | 0.00 | 105.4 ± 32 | 137 ± 42 | 0.00 |
Cholesterol (mg/dl) | 162 ± 30 | 203 ± 40 | 0.00 | 175.3 ± 33.6 | 218 ± 50 | 0.00 |
HDL-C (mg/dl) | 44.5 ± 4.4 | 34.5 ± 4.4 | 0.00 | 54.2 ± 5.9 | 37.1 ± 5.6 | 0.00 |
Triglyceride (mg/dl) | 91 ± 29.7 | 260 ± 141 | 0.00 | 82 ± 31 | 247 ± 136 | 0.00 |
Within the 20–29-year-old group of the general population, 13.4% had no abnormality (23% of males and 5.6% of females), while this figure dropped to 3.4% in people above 60 years of age (5.8% of males and 0.9% of females). Totally 13.3% of males and only 3.4% of females had no cardiovascular risk factor in the population.
The results of this study indicate that according to ATP III criteria, 23.7% of the studied adult population has metabolic syndrome. Since the study population is representative, the findings can be generalized to the whole urban population of the northern west of Iran.
The prevalence of MS varies considerably worldwide. Some of the differences in the prevalence of MS might arise from varied definitions of the syndrome. For instance, Trevisan et al. [
Although the prevalence of the metabolic syndrome in this study is higher than some previously reported from the USA, Italy, and Finland [
The exact reasons for high prevalence of MS in our study remain to be determined, but it is evident that substantial socioeconomic changes have occurred in the population over the past decades and the transition from a traditional to a western-like urban lifestyle has been associated with adverse changes in lifestyle habits. Based on the results of a national profile of non-communicable disease risk factors in Iran, 2005 [
In our study the single most common abnormality was low HDL-C (overall 73%), which is more than what had previously been reported from USA [
A positive effect of age on the prevalence of the syndrome in both sexes was detected in this study and resulted in 45.5% of MS in subjects more than 50 years. This effect has been reported in other studies [
In conclusion the present study from the northern west of Iran demonstrated that MS is a serious problem among the urban populations of this country affecting primarily older individuals. Since the Iranian population, composed mainly of those less than 30 years old, it is very likely that the prevalence of MS will be even greater in the next decades. The prevention and treatment of this condition is of major public concern and urgently requires the application of appropriate policies and considerable investment.
This study was supported by Zanjan University of Medical Sciences. We thank Dr. Amir Mogadami in the laboratory of Vali-e-asr Hospital for his help.