Prevalence of metabolic syndrome in type 2 diabetic patients: A comparative study using WHO, NCEP ATP III, IDF and Harmonized definitions

Mun Chieng Tan, Ooi Chuan Ng, Teck Wee Wong, Anthony Joseph, Yoke Mun Chan, Abdul Rahman Hejar

Department of Community Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia.
Department of Medicine, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia.
Department of Medicine, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia;.
Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia;.
Heart and Lung Centre, iHEAL Medical Centre Kuala Lumpur, Federal Territory of Kuala Lumpur, Kuala Lumpur, Malaysia.
Institute of Gerontology, Universiti Putra Malaysia, Selangor, Malaysia.

DOI: 10.4236/health.2013.510227                

Abstract

To determine the prevalence of metabolic syndrome (MetS) in Malaysian type 2 diabetic patients using WHO, NCEP ATP III, IDF and the new Harmonized definitions, and the concordance between these definitions. This study involved 313 patients diagnosed with type 2 diabetes mellitus (T2DM) at two Malaysian tertiary hospitals. Socio-demographic data were assessed using a pre-tested interviewer-administered structured questionnaire. Anthropometric measurements were carried out according to standard protocols. Clinical and laboratory characteristics were examined. Kappa (k) statistics were used for the agreement between the four MetS definitions. The overall prevalence rates of MetS (95% CI) were 95.8% (93.6-98.1), 96.1% (94.0-98.3), 84.8% (80.8-88.9) and 97.7% (96.1-99.4) according to the WHO, NCEP ATP III, IDF and the Harmonized definitions, respectively. The Kappa statistics demonstrated a slight to substantial agreement between the definitions (k = 0.179-0.875, p < 0.001), where the WHO criteria revealed the highest concordance with the NCEP ATP III definition (k = 0.875, p < 0.001). The WHO against NCEP ATP III criteria evinced the highest sensitivity (99.66%) whereas Harmonized criteria against all the other three definitions showed the highest specificity (100%) in identifying MetS. In conclusion, the new Harmonized criteria established the highest prevalence of MetS among the four definitions applied. There was a very good concordance between the WHO and NCEP ATP III criteria. The extremely high prevalence of MetS observed in type 2 diabetic patients indicates an impending pandemic of CVD risk in Malaysia. Aggressive treatment of MetS components is required to reduce cardiovascular risk in T2DM.

Keywords

Metabolic Syndrome; Type 2 Diabetes Mellitus (T2DM); World Health Organization (WHO); Third Report of the National Cholesterol Education Expert Panel on Detection; Evaluation; Treatment of High Blood Cholesterol in Adults (NCEP ATP III); International Diabetes Federation (IDF); Harmonized Definition

1. INTRODUCTION

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities that often co-exist and would lead to a marked increase in the risk of cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM) including obesity, hyperglycemia, dyslipidemia and hypertension [1-7]. The essence of the MetS lies in the clustering of these risk factors, whose presence has extensively been reported to point to an almost five-fold elevation in CVD risk [6,8-11]. Metabolic syndrome is common in individuals with diabetes mellitus (DM) and significantly more common in patients with T2DM than in those with type 1 diabetes mellitus (T1DM) [12-14]. The total CVD risk attributable to the syndrome has been observed to exceed the sum of the risk from each of the separate components [8,15]. Hence, it becomes a great burden on public health and clinical practice [16].

Metabolic syndrome consists of a multi-factorial set of indicators [2-4,7,16-19]. The World Health Organization (WHO) definition [5] was the first to tie together the key components of MetS: insulin resistance, obesity, dyslipidemia and hypertension, where the presence of insulin resistance is mandatory. With that said, this definition also allows patients with T2DM to be diagnosed with MetS if they meet the other criteria.

In 2001, the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) devised a definition for MetS [3], which was then updated in 2005 by the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) [20]. The NCEP ATP III definition did not require demonstration of insulin resistance per se and can be used in people with DM. Moreover, no single factor is essential, instead, NCEP ATP III requires the presence of three out of any five factors to establish the MetS diagnosis. The NCEP ATP III provides a definition of the MetS that is pragmatic, applicable to routine clinical practice and uses variables that are easily measurable.

In 2005, the International Diabetes Federation (IDF) published new criteria for MetS [17]. Although it includes the same general criteria as the other definitions; it requires obesity, but not necessarily insulin resistance, to be present. The obesity requirement is met by population-specific cut-points. This accounts for the fact that different populations, ethnicities and nationalities have different distributions of norms for body weight and waist circumference (WC). It also recognizes that the relationship between these values and the risk for CVD differs in different populations. For example, Asian populations have an increased risk for CVD at smaller waist circumferences that would not be considered to meet the criteria in a Western population [21].

Recently, the IDF, AHA/NHLBI, World Heart Federation, International Atherosclerosis Society, and International Association for the Study of Obesity jointly proposed a Harmonized definition for MetS [7]. By this definition, the five risk factors were identical to the IDF criteria but did not mandate abdominal obesity as a compulsory risk factor. This means any three abnormal findings out of the five would qualify a person for the MetS. Thus, the definition is not built in any preconceived notion of the underlying cause of MetS, whether it is insulin resistance/DM or obesity.

There is limited data on the prevalence of MetS among Malaysian type 2 diabetic patients and the agreement between various MetS definitions in this population. In this study, the four most popular definitions proposed by different world medical organizations were applied to define and compare the complexity of different MetS among the type 2 diabetic patients in our tertiary hospitals. We estimated the overall MetS prevalence rates among these patients, followed by quantification and subsequent comparison of the degree of agreement between the available MetS definitions.

2. METHODS

2.1. Patients and Study Location

In this cross-sectional study, we studied 313 type 2 diabetic patients from two tertiary referral hospitals in Klang Valley, Malaysia-Kuala Lumpur Hospital and Serdang Hospital. A systematic random sampling method was applied to select patients based on the inclusion and exclusion criteria. The study protocol conforms to the principles of the Malaysian Guideline for Good Clinical Practice [22] which were consistent with the Ethical Guidelines of the Declaration of Helsinki (World Medical Association Declaration of Helsinki) as reflected in priori approvals by the Committees for Medical Research Ethics of the Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, and Ministry of Health Malaysia on the understanding that patients’ data were coded and anonymity guaranteed. Additionally, all patients were aware of the nature of the study and gave informed consent prior to commencement of the interview.

Comprehensive information on patients was collected using structured questionnaire, physical examination and laboratory investigations according to standardised protocols. Patients were personally interviewed on their socio-demographic backgrounds consisting date of birth, age, gender and ethnic group. Investigation of patient’s medical history on the diseases (with T2DM as a prerequisite) was conducted, which includes the presence of hypertension and dyslipidemia, duration of diseases and treatment obtained. Medical records of all patients were reviewed and extracted according to a standardized procedure.

2.2. Anthropometric and Physiological Measurements

Anthropometric measurements at the study visits included height, weight, WC, hip circumference and waist-to-hip ratio (WHR) were measured by trained personnel according to the standard procedures. Waist circumference was measured using a non-elastic tape made of fiberglass. Patients were asked to stand erect in a relaxed position with both feet together on a flat surface, while one layer of clothing was accepted. Waist girth was measured as the smallest horizontal girth between the costal margins and the iliac crests at minimal respiration, touching but not compressing the skin. For the statistical analysis, mean values of the two consecutive WC measurements were calculated. Hip circumference was measured to the nearest 0.5 cm by using the same nonelastic fiberglass tape over the greater trochanters (the widest portion of the hip) or the widest part of the gluteal region, respectively, with patients wearing light underwear. The WHR is an indicative of regional fat distribution, and it was determined using the formula as WC divided by hip circumference. Body mass index (BMI) was used as a measure of overall obesity. Body weight was measured to the nearest 0.1 kg by the SECA digital scale (THD-360, Tanita Health Equipment Ltd., Tokyo, Japan) with patients dressed in lightweight clothing (with heavy clothing removed and 0.5 kg deducted for remaining garments). Height was measured by a wall-mounted SECA microtoise tape (Model 206, Vogel and Halke GmbH & Co., Hamburg, Germany) which was suspended upright against a smooth wall (with patients barefooted) in centimeters (cm) (to the nearest 0.5 cm) prior to conversion into meters (m). Measurements were taken in duplicate and averaged. As an estimate of relative weight, BMI was computed as weight (kg) divided by standing height squared (m²). The WHO classification of BMI was used to classify the patients as underweight (BMI < 18.5 kg/m²); normal (BMI 18.5 - 24.9 kg/m²); overweight (BMI 25.0 - 29.9 kg/m²); and obese (BMI > 30 kg/m²) [23].

Blood pressure was measured at the sitting position using a calibrated digital Omron Automatic Blood Pressure Monitor (Model T8, Omron Healthcare Singapore Pte Ltd., Alexandra Technopark, Singapore) with an appropriate sized cuff on the left arm after taking rest for at least 10 min. A cuff larger than the standard one was used when arm circumference exceeded 34 cm. Mean values of the resting systolic and diastolic blood pressure were determined from two independent measurements at 5-min intervals. All measurements were taken by the same trained personnel to reduce error.

2.3. Biochemical Parameters

Information on the routine laboratory investigations involving glycemic control and plasma lipid profiles were retrieved from patients’ medical records. The variables extracted from patients’ records include glycated hemoglobin (HbA_1C), fasting plasma glucose (FPG), serum total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides. The last available values, i.e. the latest and must be of readings within the last three months were noted. Based on the Management of Type 2 Diabetes Mellitus Clinical Practice Guidelines criteria, HbA_1c and FPG of less than 6.5% and within 4.4 - 8.0 mmol/L respectively were considered as good glycemic control [24].

2.4. Definition and Diagnosis of Metabolic Syndrome

Table 1 manifests the summary of MetS classification in accordance to WHO, NCEP ATP III, IDF, and Harmonized definitions. The traditional risk factors of MetS were defined as follows: hypertension, dyslipidemia and DM as the use of antihypertensive, lipid lowering or

Conflicts of Interest

The authors declare no conflicts of interest.

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