A global transition in the disease pattern has been observed, where the relative impact of infectious diseases is decreasing while chronic diseases like cardiovascular disease (CVD) and diabetes are increasingly dominating the disease pattern [
The metabolic syndrome (MS) is a multiplex risk factor for atherosclerotic cardiovascular disease (ASCVD). It consists of an atherogenic dyslipidemia ((i.e., elevated triglycerides and apolipoprotein B (apo-B) and low high-density lipoprotein cholesterol (HDL-C)), elevation of blood pressure and glucose, prothrombotic and proinflammatory states. The risk of ASCVD accompanying the MS is approximately doubled compared with an absence of the syndrome. The MS appears to promote the development of ASCVD at multiple levels. Elevations of apoB containing lipoproteins initiate atherogenesis and drive lesion development. Atherosclerotic plaque development is accelerated by low levels of HDL-C, by elevated glucose levels and by inflammatory cytokines [
MS is a complex web of metabolic factors that are associated with a 2-fold risk of CVD and a 5-fold risk of diabetes. Individuals with MS have a 30%–40% probability of developing diabetes and/or CVD within 20 years, depending on the number of components present [
In the United States (US), the prevalence of the MS in the adult population was estimated to be more than 25%. Similarly, the prevalence of MS in 7 European countries was approximately 23%. It was estimated that 20%–25% of South Asians have developed MS and many more may be prone to it [
In this context, the aim of this study was to assess the prevalence of MS as defined by NCEP ATP III guidelines with a modification to the value for BMI that is more applicable to the Asian Indian population, and to look for the differences between the various components constituting MS. Along with the prevalence of MS, we also studied the prevalence of various risk factors leading to ASCVD.
The current study was a population-based survey of cohort in the metropolitan city of Mumbai in Western India. Mumbai being the industrial capital of India, the inhabitants here are heterogeneous both ethnically and culturally. A total of 560 subjects, who attended the free CARDIAC evaluation camp arranged by P. D. Hinduja National Hospital and Medical Research Centre by general advertising, were recruited in the study. Among the 560 subjects, 548 (302 males and 246 females) who had all the required data for the analysis formed the study group.
Each participant was interviewed by a group of research students and completed a standardized questionnaire containing information on demographics, anthropometric profile, individual characteristics associated with the major risk factors of CVD, past medical history, and biochemical parameters (Table
Study variables for the baseline survey of CVD risk factors.
Study variables | ||
---|---|---|
Demographic | Age | |
Gender | ||
Behavioural | Smoking | |
Alcohol consumption | ||
Clinical examination | Weight | |
Height | ||
Questionnaire | History of CVD, diabetes, HTN | |
Family history of CVD, diabetes, HTN | ||
Biochemical tests | Fasting blood glucose | |
Total cholesterol (TC) | ||
Triglyceride (TG) | ||
HDL-C | ||
APOA1, APOB. RATIO | ||
Lp(a) | ||
hsCRP |
(HTN-hypertension, APO A1-apolipoprotein A1, Lp(a)-lipoprotein A, hsCRP-High sensitive C-reactive protein).
All measurements were carried out by a group of research students. Body weight was determined with subjects wearing light clothes and no shoes or socks, using an electronic balance. Height was determined using a wall mounted, nonextendable measuring tape with subjects in standing position and feet together. Body mass index (BMI) was calculated using the expression:
Blood samples were collected by venipuncture after an overnight fast for 12–14 hours. Venous blood was collected in plain and fluoride bulbs for measurement of serum lipids, Lp(a), Apolipoproteins, hsCRP, and glucose, respectively. The serum was separated after centrifugation at 3000 rpm for 10 minutes. The analysis was carried on an automated clinical chemistry analyzer, Beckman DXC 800. Serum glucose was measured by oxygen rate method employing a Beckman oxygen electrode (glucose oxidase). Total cholesterol, triglyceride, and HDL-C concentration were measured by International Federation of clinical chemistry (IFCC) approved enzymatic methods. Beckman reagents and calibrators were used for the analysis. Control sera were included in each batch of samples analyzed. hsCRP detection is based on near infrared particle immunoassay on DXC 800. Serum APO A1, APO-B, and Lp(a) were determined by rate nephelometry on IMMAGE immunochemistry system. It measures the rate of increase in light scattered from particles suspended in solution as a result of complexes formed during an antigen-antibody reaction. As a part of external quality assurance, our laboratory is enrolled with the proficiency testing surveys of college of American pathologist (CAP) and is the 1st hospital laboratory in India to be CAP accredited.
For serum lipids, we referred to National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) guidelines [ abdominal obesity Men-≥90 cm, Women-≥80 cm, serum TG > 1.69 mmol/L, HDL-C < 1.03 mmol/L, fasting blood glucose level >5.55 mmol/L, blood pressure ≥ 130/85 mmHg.
Reference ranges.
Lipid profile
Normal (mmol/L) | High (mmol/L) | |
---|---|---|
Cholesterol (TC) | <5.18 | ≥5.18 |
Triglycerides (TG) | <1.69 | ≥1.69 |
Normal (mmol/L) | Low (mmol/L) | |
HDL-C | ≥1.03 | <1.03 |
Cardiac markers ranges
Normal | High | |
---|---|---|
Lp(a) | ≤1.07 | >1.07 |
hsCRP | ≤0.75 mg/dL | >0.75 mg/dL |
APOB-MALES | <1.62 g/L | ≥1.62 g/L |
APOB-FEMALES | <1.71 g/L | ≥1.71 g/L |
Normal | Low | |
APOA-MALES | ≥0.90 g/L | <0.90 g/L |
APOA-FEMALES | ≥1.07 g/L | <1.07 g/L |
APOA/APOB ratio | ≤1 | >1 |
Glucose levels
Normal (mmol/L) | High ((mmol/L) | |
---|---|---|
FBS | <5.55 | ≥5.55 |
Body mass index
Normal (kg/m2) | Overweight (kg/m2) | OBESE (kg/m2) | |
---|---|---|---|
BMI | 18.5–22.9 | 23–24.9 | ≧25 |
The statistical analysis was performed using Stata (SE 10.1 version). Results were expressed as mean ± standard deviation (SD). Pearson’s chi-square test was applied to test the relationship of categorised independent and dependent variables. Odds ratio and their 95% confidence intervals were calculated for all
A total of five hundred and forty eight subjects participated in the study. On applying modified NCEP ATP III, consensus guidelines for defining obesity in Asian Indians and ADA, we found out that nearly 95% of the subjects had at least one abnormal parameter. The general characteristics of the study population are given in (Table
The general characteristics of the study population.
Characteristics of the study population | ||||
Characteristics | Males | Females | Total | |
20–40 YRS | 58 (18.65) | 41 (16.02) | 99 (17.46) | |
41–60 YRS | 149 (47.91) | 147 (57.42) | 296 (52.20) | .075 |
>60 YRS | 104 (33.44) | 68 (26.56) | 172 (30.34) | |
Normal | 62 (20.53) | 53 (21.54) | 115 (20.99) | |
Overweight | 147 (48.68) | 101 (41.06) | 248 (45.26) | .169 |
OBESE | 93 (30.79) | 92 (37.4) | 185 (33.76) | |
Non-smokers | 195 (74.14) | 243 (96.43) | 438 (85.05) | <.001* |
Smokers | 68 (25.86) | 9 (3.57) | 77 (14.95) | |
No alcohol consumption | 235 (75.56) | 251 (98.05) | 486 (85.71) | <.001* |
Alcohol consumption | 76 (24.44) | 5 (1.95) | 81 (14.29) | |
Normal | 233 (71.70) | 179 (69.92) | 402 (70.90) | .642 |
H/O HTN | 88 (28.3.) | 77 (30.08) | 165 (29.10) | |
Normal | 244 (78.46) | 221 (86.33) | 465 (82.01) | .015** |
H/O diabetes | 67 (21.54) | 35 (13.67) | 102 (17.99) |
(
The gender distribution was 56.75% males and 46.71% females. The age of the subjects ranged from 20 to 90 years, with a mean age in males of 54.28 years (SD = 13.89) and in females of 52.67 years (
Our results showed a mean BMI of 25.68 in males and 26.95 in females with a 95% confidence interval (CI) of (25.27–26.09 in males) and (26.3–27.6 in females), which clearly shows that the prevalence of BMI ≥ 23 kg/m2 was significant in females than in males (
Our results showed that around 15% of the participants in the study were alcoholic and smokers. The prevalence of smokers and alcoholic was highly significant in males, as compared to females. In males 41–60 age group showed high prevalence of smokers and alcoholic as compared to 20–40 and >60 age groups.
It was found in the current study that history of hypertension and diabetes increases as age advances both in males and females. Prevalence of history of diabetes was significant in males than in females (
Increased fasting blood glucose, hypertriglyceridemia and decreased levels of HDL-C were found to be more in males with high TG and low HDL-C to be highly significant (
Percentage prevalence of APO B and APO B/APO A1 ratio was found to be more in males than females. Prevalence of APO A1 was approximately similar in males and females. High levels Lp(a) and hsCRP was seen in females than in males. In females, Lp(a) and hsCRP prevalence was seen more in young adults (20–40 age group) than the other two groups under study.
The overall prevalence of MS having ≥3 components was 19.52% by modified NCEP ATP III criteria. The prevalence of MS in males was almost double (25.16%) than females (12.6%), and this was highly significant (
Age- and gender-specific prevalence of individual components of MS.
The prevalence of major risk factors of ASCVD was 45.25% overweight, 33.75% obese, 39.96% having impaired blood glucose levels, 39.96% subjects with hypercholesterolemia, 38.13% with hypertriglyceridemia, and 47.97% with low HDL-C. The prevalence of elevated cardiac markers was 2.18% with high APO B, 1.82% with increased APO A, 30.65% and 8.39% with elevated levels of Lp(a) and hsCRP, respectively (Figure
Gender-specific prevalence of different atherosclerotic risk factors.
Asian Indians are a high risk population with respect to diabetes and CVD, and the numbers are consistently on the rise [
Chow et al. [
The development of obesity, or more specifically an increase in abdominal fat, is thought to be the primary event in the progression of MS. A tendency to gain fat in the abdominal area, as opposed to the hip, buttock, and limb areas, is linked to a rise in fatty acids in the blood, which is thought to lead to insulin resistance, high blood pressure, abdominal blood lipids, and eventually diabetes. Asian Indians tend to develop central obesity rather than generalised obesity. About three fourth of the subjects participated in study were overweight/obese (
In our study, we observed approximately 15% of subjects had history of diabetes. This means that the remaining subjects with impaired blood glucose levels that is, 25% of subjects were on their way to develop diabetes, which is an important risk factor for CAD. Enas et al. [
Increased prevalence of low HDL-C has been reported earlier by Enas et al. [
The novel aspect of this study is that along with clinical and biochemical features of MS, prevalence of risk factors for ASCVD with cardiac markers was systematically assessed. Along with traditional risk factors, emerging factors present in the South Asian population are allowing for further CAD risk stratification. At the forefront is APOB/APO A1 ratio. APOB is the major apolipoprotein found in low density lipoprotein (LDL), Intermediate-density lipoprotein (IDL), and very low density lipoprotein (VLDL), and it is the primary ligand for the LDL receptor. APO A1 is the major protein constituent of HDL. The APO B/APO A1 ratio provides an atherogenic to antiatherogenic lipoprotein ratio that has been shown to be a better predictor of CVD than LDL level and HDL level. The APO B/APO A1 ratio can identify individuals with preponderance of small dense LDL particles [
Lipoprotein a (Lp(a)), considered an emerging risk factor by NCEP ATP III, has been implicated in the development of the premature atherosclerotic disease seen in South Asians [
The cardiovascular field has recently shown great interest in the role of inflammation in the development of ASCVD. The basic concept is that atherogenesis represents a state of chronic inflammation. The findings that elevations of serum CRP carry predictive power for the development of major cardiovascular events led to the concept that advanced and unstable atherosclerotic plaques are in an even higher state of inflammation than stable plaques. In our study, females (10.2%) had higher rates of elevated CRP than males (6.43%). It is of interest that obese persons and particularly those with metabolic syndrome also have elevated levels of CRP [
The prevalence of MS in the present study is much lower than that reported in an earlier study in urban Indian adults aged (20–50 years) in which the prevalence was reported to be 41.1% [
The high levels of risk observed with our baseline cross-sectional survey justify the need for establishing a surveillance system to monitor the trends of MS and ASCVD risk factors over time. Continuing surveillance efforts would provide us with an opportunity to develop evidence-based cost-effective CVD prevention, detection, and management strategies. Early intervention particularly with lifestyle change would delay the onset of advance forms of MS and a high-risk status. Regular physical activity, lifetime abstinence of tobacco, avoidance in the consumption of trans fats (fried food), and reduced intake of saturated fats together with an increased intake of fruits and vegetables form the foundation of lifestyle changes. Adopting a healthy lifestyle beginning in childhood and adolescence is warranted in view of the malignant nature of CAD among Asian Indians [
Clinical diabetes and CAD are preceded by a constellation of risk factors that are also the components of MS. In conclusion, prevalence of MS varies amongst ethnic groups. Indians are high at risk for CVD and their predispositions. The prevalence of MS was double in males as compared to females. This study revealed the increased prevalence of MS to be more prevalent in 41–60 years, suggesting that this group is at increased risk of developing CAD. It was also found that high percentage prevalence of overweight and obesity was one of the major driving forces in the development of MS. Therefore, early identification of the metabolic abnormalities and appropriate intervention may be of primary importance in populations especially like ours having high prevalence.
Due to missing/unavailability of blood pressure data, we were not able to include it in the present study, but would try to incorporate it later when we obtain complete information on the same. As cluster of three or more, risk factors can be termed as metabolic syndrome, in the current study as per NCEP ATP III guidelines abdominal obesity, HDL-C levels, triglyceride levels, and fasting blood glucose levels were taken into consideration.
The authors express their gratitude towards management and administrative staff (Dr. Preeti and Anirudh) of P. D. Hinduja National Hospital and Medical Research Centre for their support. they thank the cardiology department (Dr. Ponde, Dr. Rajani, Dr. Achyut, Dr.Sameer), biochemistry deparment (Dr. Dhanashri, Bhamini, Anita, Manjusha, Mrs. Sanghavi, Swati, Yulette, Jyoti, Mythili, Maheshwari, Asha and Sunita), marketing department, Phlebotomist, lab attendants, and the nursing staff for their constant help. Special thanks to all the research students (Minal, Kanchan, Namita, Himangi, Amruta P, Amruta K, Payal, and Viral D) for their enormous help and support to organize the event.