The prevalence of metabolic syndrome and its predominant components among pre-and postmenopausal Ghanaian women

Chronic health problems such as cardiovascular diseases and type 2 diabetes have become major public health concerns worldwide including Ghana [1].

Metabolic syndrome, also known as Syndrome X, Insulin Resistance Syndrome or Dysmetabolic Syndrome, is a common condition that predisposes individuals to the risk of developing cardiovascular diseases and type 2 diabetes. The syndrome is the assemblage of risk factors such as central obesity, high blood pressure, hyperglycaemia, impaired glucose tolerance, hypertriglyceridaemia as well as low levels of high density lipoprotein cholesterol [2]. It is estimated that about 20–25 per cent of the world’s population have the metabolic syndrome and are three times more likely to die from heart attack or stroke compared with people without the syndrome [3]. The risk of cardiovascular diseases assigned to metabolic syndrome seems to be particularly high in women with the estimation that half of all cardiovascular events in women are linked to metabolic syndrome [4].

The aetiology of the syndrome is not clearly defined, but it is linked to visceral obesity [5]. Hence, the theory of metabolic changes in postmenopause and increased abdominal obesity as a result of decrease in oestrogen production is one of the hypotheses that is used to explain the increased incidence of the syndrome during this period [6].

The prevalence of the syndrome differs greatly in different populations. Amongst pre-and postmenopausal women it ranges from 13.8% to more than 60.0% [7–11]. Neto et al., [10] estimated prevalence of the syndrome among Brazilian pre-and postmenopausal women to be 24.0% and 44.4% according to NCEP ATP III criterion. Similarly, the prevalence of the syndrome was 13.8% and 54.6% among Korean pre-and postmenopausal women respectively [7]. It is postulated to increase with age with about 40-50% occurring in postmenopausal women [12]. This increase has also been ascribed to menopause and ethnicity [10, 13]. Lifestyle modifications such as increase in physical activity and consumption of low caloric diets coupled with reduced intake of alcoholic beverages have been shown to alter the prevalence and gravity of the syndrome as well as to downgrade insulin resistance in women [14, 15].

The Ghana Demographic and Health Surveys (GDHS) indicated that the percentage of women aged 15–49 years being overweight or obese grew from 25% to 30% between 2003 and 2008 with the highest values among urban women [16]. There is paucity of data on the prevalence of the syndrome among pre-and postmenopausal women in developing countries, such as Ghana. However, the increasing adaptation of “western” lifestyle coupled with the increased tendency of weight gain after birth in Ghanaian women warrant such a study. The principal components of this syndrome also need to be locally documented as a result of differences in the cut-off levels of the predominant components of metabolic syndrome in Ghanaian women and that of other countries [17]. The significance of these inconsistencies is the yield of various criteria which could affect diagnosis of metabolic syndrome in the same population. There is no data on the prevalence of metabolic syndrome and its predominant components among pre-and postmenopausal women in Ghana. Also no study in Ghana had compared the output of four diagnostic criteria for defining metabolic syndrome in the above population. There is the need to assess the agreement of these criteria in Ghanaian women.

This study, therefore, sought to determine the prevalence of metabolic syndrome and its predominant components among pre-and postmenopausal Ghanaian women in the Kumasi Metropolis, Ashanti Region, Ghana using WHO, NCEP-ATP III, IDF and H_MS diagnostic criteria.

MetS has become a public health problem due to its link to diseases such as ischemic heart disease, stroke, dementia, non-alcoholic steatohepatitis, polycystic ovarian disease, haemochromatosis, endometrial and oesophageal cancers [25]. Even though the concept was coined several decades ago, the comparison of prevalence between populations was made possible after the standardization of diagnostic criteria. The differences in genetic profile, lifestyle factors such as eating habits and level of physical activity, age, menopausal status and gender determine the prevalence and the predominant components of MetS in a population [26].

The present study assessed the prevalence of MetS and its predominant components among pre- and postmenopausal Ghanaian women. The prevalence of MetS as observed in this study increased from 14.4% through 25.6% to 29.2% and further to 30.4% when the WHO, NCEP ATP III, IDF and H_MS criteria respectively were used (Table 3). The prevalence of MetS varies among women and depends on the characteristics of the population as well as the diagnostic criteria applied [18, 27]. This study considered four different diagnostic criteria and each gave different degree of prevalence and these results are in agreement with studies carried out among Brazilian, Chinese, German and Korean women which estimated the prevalence of MetS, to range from 10.7% through 20.9% and 33.7% to 36.1% [2, 10, 18, 27–29]. The degree of agreement between H_MS and IDF criteria was very good, (weighted kappa = 0.97). The overall degree of agreement between WHO/NCEP, WHO/IDF and WHO/H_MS was moderate (0.53, 0.47 and 0.47 respectively). Choi and colleagues estimated similar degree of agreement between WHO and NCEP criteria among Korean population [30]; however there was paucity of data comparing the agreement between all the four criteria together.

When WHO diagnostic criterion was used, the prevalence of MetS among postmenopausal women was higher (25.2%) compared to their premenopausal counterparts (6.3%) (Table 3). This finding is consistent with a study conducted in 2008 with 200 climacteric (menopausal) women in Pakistan, which found MetS in 21.0% of postmenopausal women against 7.0% of premenopausal women using the same criterion [31]. Piche and colleagues [32] found prevalence of 29.6% among Canadian postmenopausal women using the WHO criterion. Applying the NCEP ATP III criterion, the prevalence of MetS was estimated to be higher among postmenopausal subjects in the present study (41.1%) than their premenopausal counterparts (14.7%). This confirms that the prevalence of MetS can differ in a population depending on the criterion used. This observation is similar to studies carried out among premenopausal Korean and postmenopausal Ecuadorian women respectively which estimated the prevalence of MetS to range from 13.8% to 41.5% using the NCEP ATP III criterion [33, 34]. Pandey and colleagues [35] found prevalence of MetS among Indian women to be 56% using NCEP ATP III criterion whereas 33.7% prevalence rate of MetS was observed by Ruan et al.,[29] using IDF criterion among Chinese women. Certainly, lifestyle and genetic characteristics of Ghanaian women are likely to be significantly different from women from China and India and these may explain the differences in prevalence rates of MetS obtained.

In addition, the prevalence of MetS was higher among postmenopausal women [(43.0% (IDF) and 43.9% (H_MS)] than premenopausal women [(18.9% (IDF) and 20.3% (H_MS)] (Table 3). Pandey et al., [36] used both criteria to estimate higher prevalence of MetS among postmenopausal Indian women compared to their premenopausal counterparts. In their study, the prevalence of MetS among postmenopausal women was higher than in the premenopausal group by both, IDF (premenopausal 45% and postmenopausal 55%) and H_MS criteria (premenopausal 44% and postmenopausal 56%). The differences in the prevalence rates in both present and Indian studies may be explained by differences in socio-cultural practices, lifestyle, as well as genetic compositions. The prevalence of metabolic syndrome in the study population might increase in future as most of the women especially postmenopausal group, had metabolic scores of 2 when all the diagnostic criteria were considered. The findings from this study suggest that the prevalence of MetS is dependent on age regardless of the criteria used. The influence of age on MetS among pre-and postmenopausal women is important and this trend has been established in similar populations elsewhere [10, 36]. This explains why postmenopausal women had higher age-specific prevalence of MetS than their premenopausal counterparts when all the four diagnostic criteria were applied (Figure 1a and b). The age-specific prevalence of MetS peaks at ≥60 years for postmenopausal women. These findings are in partial accordance with those observed in Seychellois [37] women where the prevalence of MetS was highest among 55–64 years old. Physical activity and lean muscle mass naturally diminishes with age in women [38]. The body composition of women shifts to more fat and less muscle which slows down the rate at which the body metabolises biomolecules and results in weight gain especially central fatness culminating in metabolic abnormalities and higher MetS prevalence.

Premenopausal Ghanaian women develop MetS earlier (20–29 years) when NCEP ATP III, IDF and H_MS criteria were applied. This result is concurrent with the study conducted by Kim et al., [7] which identified the onset of MetS to be 20–29 years among Korean pre-and postmenopausal women. The reason for marked increase in the prevalence of MetS among premenopausal individuals at the age group of 20–29 years (32.7%) and 30–39 (20.0%) is not known, though it is possible these women might have kept positive caloric balance for some time and this had resulted in an increase in their obesity indices, blood pressure and lipid profile. Insulin sensitivity and glucose intolerance are not entirely explained by a woman’s hormonal status. There are now data showing that weight gain in women is a stronger predictor of impaired glucose tolerance than menopausal status [39].

Examination of the Ghanaian women with MetS using the three diagnostic criteria identified central obesity, raised blood pressure and raised fasting glucose (WHO, IDF & H_MS) as the predominant components (Table 4). The components of MetS were common in the postmenopausal group when they were analyzed in relation to menopausal status. Oliveira et al., [40] found similar order of frequency of components respectively with the following proportions: central obesity (84.1%), raised blood pressure (53.6%), raised triglycerides (18.1%) and raised fasting glucose (16.7%). However, Oh et al., [18] in their study of 449 South Korean women listed the following predominant components: reduced HDL-C, raised blood pressure, raised triglycerides, raised fasting blood glucose and abdominal obesity. Contrarily, NCEP-ATP III criterion identified raised blood pressure, central obesity and raised fasting blood glucose as the predominant components in Ghanaian women. In premenopausal women, fat accumulates in lower extremities, to a greater extent, as a result of oestrogen secretion. After meals, the flow of blood containing high levels of chylomicrons to fat stored in the thighs and hips increases in women, but not in men [41]. Furthermore, the fats stored around the hips and thighs serve as storage form of energy during pregnancy as well as cushion for the reproductive organs [41]. These could be the reasons why women store more fat in their lower body. However, during menopause the pattern of hormone secretion changes and gradually causes fat accumulation in visceral tissues of abdomen which results in central obesity [42]. A lot of metabolic changes in postmenopausal women are related to the decrease in oestrogen secretion and consequent accumulation of abdominal fat. Moreover, central obesity is linked to a greater amount of visceral fat than to lower-body obesity, which is associated with more subcutaneous fat. Visceral fat produces free fatty acids and inflammatory cytokines which directly drains into the portal vein, and is thus likely to have a direct signalling and metabolic relation with the liver in comparison to subcutaneous fat [43, 44]. Fat deposits in the liver are associated with the overproduction of very low-density lipoprotein predisposing women to atherogenic dyslipidaemia (elevated triglyceride, low HDL-cholesterol level, and small dense LDL cholesterol particles) [44, 45]. Elevated levels of small dense-LDL-cholesterol get entrapped in the endothelium of the arterial wall and are oxidized leading to arterial stiffness and atherosclerosis [46] and these can culminate in high blood pressure and related conditions. Ghanaian women showed abdominal obesity and raised blood pressure especially among postmenopausal group and this may be due to the fact that they generally have adopted western lifestyle of consuming high-energy food whilst undertaking limited physical exercise.

Plasma TG and HDL-cholesterol are known to be inversely correlated from epidemiological studies [47, 48]. The enzyme cholesteryl ester transfer protein (CETP) balances the levels of TG and HDL-cholesterol by mediating the transfer of triglycerides (TGs) from TG-rich lipoproteins to HDL and LDL particles in exchange for cholesteryl. esters which leads to low HDL-C and high small dense-LDL-C [49]. It has been proposed that high CETP activity explains some of the high TG levels and low HDL-C levels (dyslipidaemia), observed in persons with MetS [50]. In this study, menopause was associated with an increase in serum triglyceride but mean levels of HDL-cholesterol were similar between premenopausal and postmenopausal women (Table 2), which is consistent with the observation among Korean women by Kim et al., [33].

The present study also demonstrated that the prevalence of BMI overweight, WHR obesity, WHtR obesity, hyperglycaemia and hypertension were significantly higher among postmenopausal group compared to the premenopausal population whilst WHR overweight was the reverse. This finding is in disagreement with the study of Jaber et al., [51] which listed only low HDL cholesterol and raised fasting glucose as the predominant components of MetS among Arab American women. This could be attributed to differences in genetics and environment. Other studies have shown that the above components are predominant indicators of MetS [2, 7, 29] however, menopause has been established to increase the risk of women to above-mentioned factors [52, 53]. This further buttresses the point that postmenopausal status is an independent risk factor for MetS and all of its individual components [54]. Moreover, postmenopausal women are thought to accumulate more fat in the intra-abdominal depot than do premenopausal women and therefore have a greater risk of developing metabolic complications associated with obesity [55].

The strength of this study is that all variables were measured using standard methods and vigorous quality control. However, our cross sectional study design and small sample size does not allow us to generalize the findings to all women in Kumasi metropolis. Another limitation of our study is the age difference between pre-and postmenopausal women which could also influence the prevalence of metabolic syndrome in both groups. Therefore future prospective studies should be used to confirm the difference in prevalence of metabolic syndrome in large population of age-matched pre-and postmenopausal women in Ghana.

The findings in this study revealed the presence of metabolic syndrome among Ghanaian women. The syndrome was higher among postmenopausal women, irrespective of diagnostic criteria used. Age had a major influence on the prevalence and the individual constituents of the syndrome. The predominant components identified were central obesity, raised blood pressure and raised fasting blood glucose in the order of frequency. Conscious control of these individual constituents is achievable and must be encouraged in the population. Metabolic syndrome has become a significant health problem in our contemporary world and therefore all efforts should be made to create local awareness, early diagnosis and prevention. This can decrease the burden on our limited health resources, prevent complications such as type 2 diabetes, cardiovascular diseases, and reduce morbidity and early mortality among women. Women, still in their childbearing age, should also be advised to balance their energy intake and expenditure in order to reduce the alarming rate of the syndrome incidence. Moreover, exercise and consumption of low caloric foods will improve plasma lipid concentrations by raising their HDL cholesterol concentrations [56], decrease triglycerides concentrations [57] or both [58]. Furthermore, physical activity is linked with lowered blood pressure, improved glucose intolerance, insulin sensitivity and lowered risk of type 2 diabetes [59].