Discussion, Conclusion and Limitations
4.2 The Metabolic Syndrome
175
& Barker, 2001, Misra et al., 2004). In addition, the theory of a prothrombotic state in Asian Indians has been suggested (Anand et al., 2000; Hoogeveen et al., 2001), promoted by higher homocysteine, lipoprotein (a), and plasminogen activator inhibitor- 1 levels than are observed in Black (McKeige et al., 1991; Kain et al., 2008) or Caucasian populations.
The high CV risk profile observed in our study may be explained by the mechanisms discussed above, and particularly by the changes in socio-economic status with resultant changes in dietary patterns to more high-fat-and highly processed carbohydrate-based meals and a sedentary lifestyle. Consequently, these were the factors that were suggested to have accelerated the development of over-weight and obesity in the Indian diaspora in Mauritius (Dowse et al., 1995) and in Trinidad (Gulliford et al., 2001;
PAHO/WHO, 1999). Similar conclusions have also been made previously in subjects sharing the same environmental exposure in KwaZulu-Natal (Motala et al., 2011; Seedat et al., 1990; Omar et al., 1988, Ranjith et al., 2002). Our study has drawn attention to the very high risk profile in the same community developing only two decades later, which has been signaled by a surge in the prevalence of obesity, dysglycaemia and DM beginning in early adolescence.
176 even before the development of overt DM. Currently there still remains disagreements about the diagnostic criteria of MS and debate about whether MS is a true syndrome or a mixture of various phenotypes (Alberti et al., 2009). The current research, however, suggests that the components may have common genetic mechanisms as they tend to occur concomitantly, or cluster together.
4.2.1 The prevalence of the Metabolic Syndrome
The present study shows that there is a very high prevalence of MS in the Phoenix community, with the varying prevalence attributed to the definitions that were used.
The crude prevalence of MS was found to be 38%, 46% and 41% when the NCEP ATP III, IDF and Harmonizing criteria were applied, respectively (Table 3-9). The increase in prevalence using the different criteria was mainly attributable to the ethnic-specific waist circumference cut-offs used in the IDF and Harmonizing criteria, which, in this case, identified more subjects with the syndrome than did the NCEP ATP III criteria.
This prevalence was higher than what has been reported recently in the United States (34%) by the American Heart Association (2011), and much higher than those reported for other population groups in South Africa, namely, 30% in Caucasians (Ker et al., 2007) and 23% in the African population (Motala et al., 2011). By whatever criteria used, our sample showed a much higher prevalence when compared to the 24.9% which was reported for an urban Asian population in India (Gupta et al., 2004) and in also excess of that reported recently in Asian Indians in the United States (Misra et al., 2010) as 26.7%
and 38.2 % for the NCEP and IDF criteria respectively. This study therefore highlights the
177 importance of determining ethnic-specific analysis of the prevalence of the syndrome, and not just extrapolating results from other studies (Al-Shaer, 2005).
The present study also shows significant differences in the prevalence of MS amongst men and women, as females were almost twice as likely to have the syndrome as males (Table 3-9), in contrast to the general view that MS is equitably distributed between the sexes (Grundy, 2008). This finding was not altogether unexpected and may be ascribed to the greater frequency of general and abdominal obesity, as well as DM (Table 3-11) in females. This pattern has also been reported in other Asian Indian migrants by Misra &
Khurana (2009), and by Ford et al. (2002) who described a higher prevalence of MS in the females of their respective cohorts. Recent studies in Asian Indian males (Chow et al., 2007; Deepa et al., 2007), in Germany (Dekker et al., 2005) and in Greece (Skoumas et al., 2007) have begun to show increasing prevalence data for MS in males.
The prevalence of MS also increased with ageing (Figure 3-4), and is probably due to the increased exposure of ageing individuals to CVD risk factors to a point where they are clinically evident. The increase in prevalence with advancing age was most discernible in females (Figure 3-4), and has also been reported in females from other ethnicities (Ford et al., 2004; Ford 2005). The pattern seen in males was different, with the prevalence of MS peaking in the 4th age groups (45-54 age groups), and decreasing in the 5th age groups (55-64 age groups). This pattern has also been recently described by Misra et al.
(2010), who describes it as the characteristic Asian Indian male pattern, where dysmetabolism is observed early in life.
178 The trends with regards to MS and ageing were also different when compared to a recent study conducted in Botswana on health personnel, where the researchers (Garrido et al., 2009) found that highest prevalence was in the 35-54 age groups.
Interestingly, this was attributed to the changing lifestyle patterns to Westernisation, which the authors believed, afflicted the young more than the old (who remained set in their traditional habits). Their findings therefore underscored the importance of early detection and intervention in the younger subjects of the sample.
4.2.2 The distribution and relationship of individual MS components
McNeill et al., (2005) describes a gradient of risk for the development of CVD that is associated with increasing numbers of MS components. The 45-54 age groups appear to be the worst affected in terms of the number of MS components, as this group comprised of the largest number of subjects with more than 1 MS component (Figure 3.5). The greatest number of subjects with all 5 MS components was in the 55-64 age groups. This is probably attributed to the increased exposure of these older individuals to CVD risk factors, developing from the effects of a sedentary lifestyle, a cholesterol- rich diet and the genetic contribution (Grundy, 1997), with ensuing insulin resistance and obesity, which are regarded as the main contributors of MS. What was also emerged from our study was that the MS was not confined to those subjects with DM, but was also present in subjects with prediabetes and even normal glucose tolerance.