Prevalence of metabolic syndrome estimated by International Diabetes Federation criteria in a Hungarian population

Abstract

Aims. In recent years, metabolic syndrome (MS) became a distinct pathological entity. MS is positively associated with cardiovascular mortality. The prevalence of MS is high and a continuing increase is expected. For this reason, all attempts to prevent or manage MS by interventions are extremely important. The new set of definition by International Diabetes Federation (IDF) standardizes criteria for the diagnosis of MS and facilitates its recognition. In a large sample (n = 13 383) of outpatients visiting their general practitioners, we determined the prevalence of risk factors of MS according to the earlier Adult Treatment Panel (ATP) III and the new IDF criteria. Methods and results. The age‐standardized prevalence of MS was 14.9% in males and 8.6% in females (11.5% for all). The most prevalent factors were obesity (ATP III: 38.8% and IDF: 60%) and hypertriglyceridemia (34.1%). Hypertension dominated in men (28.7%), whereas in women obesity was the most prevalent factor (ATP III: 47.4% and IDF: 64%). Conclusion. The prevalence of MS depends on applied definition. The new IDF criteria offer the possibility of focusing on the importance of different components. The real comparison of prevalence among special populations has to be based on age‐standardized data and the use of the same components. In our study, the dominance of obesity, hypertension and hypertriglyceridemia appears to be the major detrimental factors. The 11.5% general prevalence of MS in Hungarians, which means a 25–30% value in the middle‐aged population, needs an urgent preventive approach with lifestyle changes.

• Hungarian population
• IDF
• metabolic syndrome
• prevalence

Introduction

Metabolic syndrome (MS) is characterized by the simultaneous presence and interaction of cardiovascular risk factors, including abdominal obesity, elevated blood pressure and glucose level, and dyslipidemia. This syndrome is associated with the development of diabetes, cardiovascular diseases and kidney impairment [1,2]. Increased cardiovascular risk may be explained by individual risk factors of MS in association with other, not routinely measured factors of MS like impaired fibrinolysis, oxidative stress, increased small dense low‐density lipoprotein, hypercoagulability, inflammation and hyperinsulinemia.

The increasing prevalence of this condition is a major concern for healthcare providers in both Europe and North America. However, to date there is very little activity to identify or treat this dangerous cluster of risk factors. Probably, the new unification of definition of MS provided by International Diabetes Federation (IDF) will speed up information gathering about the prevalence and importance of MS [3].

MS can be diagnosed according to several definitions. The precise determination of MS has changed slightly from time to time, and there have been a number of attempts to develop standardized criteria for its diagnosis. Most commonly used are the definitions proposed by the World Health Organization in 1998 [4], and the working characterization suggested by the Adult Treatment Panel III [5]. Ford & Giles compared the prevalence of MS in the United States according to the above‐mentioned two definitions and no difference in prevalence was found [6]. The factors included in ATP III are easier to measure in daily clinical practice, which is the reason why most investigators decided to use this definition. However, for clinical, epidemiological and surveillance purposes, it has been claimed to use a composite classification. The use of the new IDF definition has begun, whereas the question has been raised whether this model can improve our risk stratification.

The aim of our study was to evaluate the prevalence of MS according to the National Cholesterol Education Program ATP III and IDF diagnostic criteria in a large sample of the Hungarian population.

Material and methods

Study population

From May to November 2004, a total of 13 383 adults in Hungary (6322 males, 7061 females), aged 20–90 years (mean 59.4±12.5 years) visiting their general practitioners (114 GPs proportionally across the whole country) were consecutively recruited after taking into consideration exclusion criteria including renal and hepatic failure, hematological and oncological diseases, hormonal treatment and pregnancy.

Forty‐three per cent used antihypertensive medication, 14% received hypoglycemic agents or insulin, and 19% used antilipidemic medication.

Measurements of height and waist circumference (WC) rounded to the nearest 0.1 cm and weight rounded to the nearest 0.1 kg was performed. Body mass index (BMI) was calculated using weight (in kilograms) divided by the square of the height (in meters squared). Arterial blood pressure was measured and the means of replicate measurements were used in all analyses. Our study complies with the Declaration of Helsinki and the local ethics committee has approved the research protocol. Informed consent was obtained from each subject.

Biochemical analysis

Subjects were asked to fast for 12 h before venipuncture. Samples were stored at 4°C, and then analysis was carried out within 24 h. Blood glucose level was determined by using a glucose oxidase method. Total cholesterol and triglyceride levels were measured by routine enzymatic methods.

Definitions

According to the ATP III criteria, subjects having three or more of the following abnormalities were defined as having MS: (i) WC>102 cm in males or >88 cm in females; (ii) hypertension (>130/85 mmHg), (iii) hypertrigliceridema (>1.7 mmol/l); (iv) low high‐density lipoprotein cholesterol (HDL‐C) levels (<1.0 mmol/l in males and <1.3 mmol/l in females); (v) high fasting blood glucose levels (>6.1 mmol/l).

A new definition proposed by the IDF and adopted by the European Association for the Study of Diabetes (EASD) and the European Atherosclerosis Society (EAS) is also available. The IDF retained three of the five NCEP ATP III diagnostic criteria, but set new thresholds for obesity (WC>94 cm for European men and >80 cm for European women) and fasting plasma glucose (>5.6 mmol/l) as suggested by the American Diabetes Association (ADA). A diagnosis from IDF criteria requires abdominal obesity plus any two of the other four criteria.

Subjects who did not meet the criteria of high blood pressure, high fasting glucose or high triglyceride level but were treated with anti‐hypertensive, antidiabetic or antilipidemic drugs were also considered to meet the criteria for high blood pressure, high fasting glucose or hypertriglyceridemia, respectively.

Statistical analysis

The given distributions were derived by weighting of the raw data with the weights calculated from census 2005. All the means and distributions were determined from the weighted data. Age was characterized by its mean value and standard deviation. All other variables were described by their distribution by age groups (20–29, 30–39, 40–49, 50–59, 60–69 and >70 years) and gender (male/female).

Results

Age distribution of participants shows a shift to the older generation compared to the total Hungarian adult population aged 30–60 years (Table I).

Table I. Distribution of the whole population and the survey's participants according to age (%).

	40–49 years		50–59 years		60–69 years
	M	W	M	W	M	W
Hungarian population	39.8	36.1	36.0	35.3	24.2	28.6
Present survey	27.7	28.3	37.3	36.5	35.0	35.2

M, men; W, women.

The prevalence rate of MS defined by ATP III and IDF criteria is shown in Table II and its magnitude increased with age until the 60th year in both genders. This increasing trend can be attributed to similar age‐related trends in the case of each factor of MS. The prevalence of individual factors of MS using ATP III and IDF criteria is also presented in Table II. In both definitions of MS, obesity in women and hypertension in men was the most common factor. Obesity, hypertension and hypertriglyceridemia composed the most widespread combination of metabolic abnormalities according to both criteria. Using the IDF model, the prevalence of obesity and MS is about twice as much as the results calculated by ATP III. In comparison with other populations, dominance of obesity and hypertriglyceridemia appears to be the major detrimental factors. The prevalence rate of hypercholesterolemia, which is not part of MS, was extremely high both in women and men (56.4% and 50.9%, respectively).

Table II. Age‐standardized prevalence (%) of individual components of MS using ATP III criteria and total cholesterol values.

Age group	Hypertension	Hyper TG	Hypo HDL‐C	Hyper FBG		Obesity		MS^a		Hyper CHOL
				ATP III	IDF	ATP III	IDF	ATP III	IDF
Man
20–29	8.7	7.4	0	4.8	5.7	4.9	4.1	5.8	2.6	6.8
30–39	12.0	18.1	0	11.7	14.6	16.4	12.5	16.2	8.6	18.9
40–49	16.3	18.7	13.9	14.7	17.1	22.4	21.7	22.6	14.7	19.3
50–59	22.9	22.1	45.3	22.3	22.5	25.4	23.2	30.3	20.4	22.9
60–69	15.3	14.3	29.4	18.5	17.6	20.2	18.6	16.2	12.0	16.5
⩾70	24.4	19.0	11.3	27.8	22.4	10.7	19.7	8.6	41.3	15.2
Total	100.0 (28.7%)	100.0 (38.8%)	100.0 (35.7%)	100.0 (23.0%)	100.0 (35.2%)	100.0 (31.1%)	100.0 (55.4%)	100.0 (6.7%)	100.0 (14.9%)	100.0 (50.9%)
Women
20–29	5.2	9.7	0	3.7	5.6	2.2	3.87	0.0	4.0	10.9
30–39	10.6	10.9	0	9.4	8.7	13.6	12.7	3.5	4.0	13.5
40–49	17.1	17.1	14.6	12.8	15.6	19.9	21.1	12.6	18.1	17.3
50–59	24.2	23.8	43.6	22.8	24.5	25.6	24.5	24.9	31.6	20.2
60–69	21.4	19.5	30.5	23.8	22.4	22.3	21.2	46.0	24.7	18.7
⩾70	21.3	18.8	11.1	27.1	22.9	16.4	16.4	12.8	17.2	19.1
Total	100.0 (22.7%)	100.0 (29.8%)	100.0 (26.4%)	100.0 (16.5%)	100.0 (25.7%)	100.0 (47.4%)	100.0 (64.0%)	100.0 (9.8%)	100.0 (8.6%)	100.0 (56.4%)
All	25.6%	34.1%	30.8%	19.6%	30.2%	38.8%	60.0%	8.3%	11.5%	53.8%

^aThe most frequent variation calculated (obesity, hypertension, hypertriglyceridemia). ATP, Adult Treatment Panel; CHOL, cholesterol; FBG, fasting blood glucose; IDF, International Diabetes Federation; MS, metabolic syndrome; TG, triglyceride.

The ratio of patients receiving medical treatment was 83% for hypertension, 58% for hyperglycemia and 28% for hypercholesterolemia. In the treated patients' group, the number of subjects achieving the target values has been found to be the highest in hypertension (34%) and the lowest in hypercholesterolemia (14%).

Discussion

The recent statement issued by American Diabetes Association (ADA) and European Association for the Study of Diabetes (EASD) discouraging the use of the term “metabolic syndrome”. The ADA states that we should just treat each risk factor and it is not important that they cluster together. Meanwhile the American Heart Association (AHA) and the National Heart, Lung and Blood Institute (NHLBI) produced a statement on the diagnosis and treatment of MS [7], which is just a routine update and was in press before the ADA/EASD issued their statement. This report strengthens the position that MS is important. More recently, Dr Scott Grundy chaired the panel behind the AHA/NHLBI statement reacting to the ADA/EASD opinion, which expressed the significance of a multiple‐risk‐factor approach, as the practitioners treating MS and cardiovascular medicine cannot deal with risk factors in isolation [7].

One of the latest estimates suggests that MS (in its current definition) is responsible for about 6–7% of all‐cause mortality, 12–17% of cardiovascular disease and 30–52% of diabetes [8],[10,11]. Further research is needed to establish the use of MS as a predictive tool of risk of death, cardiovascular disease and diabetes in various population subgroups.

Epidemiological studies have shown that MS occurs in a wide variety of ethnic groups including Caucasians, African‐Americans, Mexican‐Americans, Asian‐Indians and Chinese [8],[10,11]. The prevalence of this syndrome depends on the applied definition. Tables III and IV summarize the prevalence of MS and its factors in different populations according to the ATP III criteria [12–21]. Several ethnic groups, including Hispanics and South Asians, seem to be particularly susceptible to this syndrome [10],[12]. The lowest general occurrence of MS was revealed in Japan and in southern Europe (Spain, Italy) [19,20],[22], whereas the surprisingly low (4%) prevalence in Slovakia needs further evaluation [16]. Very few national representative surveys have been done in the central and eastern European populations to estimate the clustering of factors of MS. Our survey seems to be the biggest one in this region so far. Among the factors of MS, hypertriglyceridemia and obesity are dominant and they were more frequent in MS patients than in other populations. On the other hand, it is very hard to compare the given prevalence (Tables III and IV) because of the lack of age standardization in some reports. Furthermore, it is not known in many studies what the mentioned age adjustment covers (making independence of age, or standardization according to the same population's age distribution)?

Table III. Prevalence (%) of individual risk factors composing metabolic syndrome after Adult Treatment Panel III definition and total cholesterol values.

Country	No.^a	Hypertension			Hypertriglyceridemia			Low‐HDL‐Chol			Hyperglycemia			Obesity			Hypercholesterinemia
		W	M	All	W	M	All	W	M	All	W	M	All	W	M	All	W	M	All
China [12]	15540	38.4	44.2	41.2	24.6	24.9	24.8	46.5	21.9	33.9	12.6	12.8	12.7				13.9	1.7	7.7
Greece [14]	4153	–	–	37.6	–	–	25.7	–	–	24.7	–	–	18.2	–	–	56.8	–	–	–
Hungary	13383	22.7	28.7	25.6	29.8	38.8	34.1	26.4	35.7	30.8	16.5	23.0	19.6	47.4	31.1	38.8	56.4	50.9	53.8
India [13]	1091	40.0	41.1	47.2	28.6	32.3	30.4	90.2	54.9	72.9	16.1	16.9	6.4	44.0	21.8	33.1	44.7	37.4	40.3
Italy [22]	2100	40.0	51.0	44.9	27.0	13.0	19.0	30.0	29.0	29.5	10.0	14.0	11.7	56.0^c	16.0^c	38.0^c	–	–	–
Poland [17]	11546	–	–	24.2	–	–	–	–	–	–	–	–	–	30.0^b	10.0^b	–	–	–	–
Slovakia [16]	501	–	–	43.0	–	–	39.0	–	–	–	–	–	10.0	–	–	30.0^b	–	–	59.0

^aNumber of screened subjects. ^bAccording to BMI (>30 kg/m²). ^cLower values used. W, women, M, men

Table IV. Prevalence (%) of metabolic syndrome in different populations after Adult Treatment Panel III criteria.

Country	No^a	Women	Men	All
China [12]	15 540	17.8	9.8	13.7
Finland [8]	–	–	8.8	–
Greece [14]	4153	–	–	23.6
Hungary	13 383	9.8	6.7	8.3
India [13]	1091	30.9	18.4	24.9
Italy [22]	2100	15.0	18.0	16.3
Japan [19]	119 412	–	–	14.6
Slovakia [16]	501	–	–	4.0
South Korea [21]	1108	39.2	29.2	∼34.4
Spain [20]	7256	3.0	8.7	5.8
Turkey [18]	1637	39.1	23.7	33.4
USA [10]	–	23.4	24.0	23.7
Mexican‐Americans				31.9

^aNumber of screened subjects.

For the improvement of interpopulational comparison, new criteria for MS were created. In one of the first reports using these new IDF criteria, the METS‐GREECE study, the age‐adjusted prevalence of MS was 43.4% (+77%, p<0.0001 compared to the NCEP ATP III definition) and included the majority of subjects older than 50 years [14].

In our study, the age‐standardized prevalence of MS was 14.9% in males and 8.6% in females (11.5% for all), which is remarkably lower than in previous study. It is hard to understand the huge discrepancy between the results of the two studies (see the consideration about age adjustment and age‐standardization processes). In our study, compared with the ATP III definition, the prevalence of MS by the IDF criteria was definitively higher (more than twice) only in men, whereas a decrease was found in women. It means that in women, abdominal obesity is not as important, regarding its association with MS, as it is in men. This is demonstrated by the lack of any real increase of MS's prevalence in subjects having a higher than 80‐cm value and it means that women between 80 and 88 cm have few risk factors.

Anyhow, the new IDF criteria may be the first step for unification of definitions of MS. The next critical point is, which components of MS would be used for definition? Because the most frequent constituents are obesity, hypertension and hypertriglyceridemia, it seems to be reasonable to use them for comparison ( = “metabolic obesity”). Because hypertriglyceridemia is associated in most cases with a low level of HDL cholesterol (this inverse association is a main contributor of the development of atherogen dyslipidemia), only one remaining component, the impairment of glucose metabolism, is not presented in this model of definition. It could be a crucial decision to detach diabetic metabolism from metabolic obesity. In later conditions (IFG, IGT, diabetes mellitus), the high cardiovascular risk and the required treatment modalities are well known. In contrast, it is not recognized that MS without disturbances of the glucose metabolism indicates the same magnitude of cardiovascular risk and is a precondition to the development of insulin resistance. In this case, the identification of MS without any overt signs of CVD or insulin resistance is meaningful and prompts urgent treatment of all components. In this assessment, MS belongs partly to primary prevention and the strict IDF criteria could promote the earliest interventions concerning firstly lifestyle modification.

We stress the benefit of the new IDF criteria and emphasize the need of further specification of the definition (e.g. restriction to three components) and the common use of age‐standardized data.

Acknowledgements

The authors hereby declare that none of them has any conflict of interest.