Men in Macau SAR have higher prevalence in metabolic syndrome and among related metabolic components: a cross-sectional Macau Health Survey

China, due to its large geographical area, varies substantially in demographic characteristics, cultural behaviours and lifestyle habits. This may result in different disease prevalence across the regions, especially those tightly connected with lifestyle behaviours. Metabolic syndrome (MetS) and its components, has been strongly associated with diabetes and cardiovascular mortality [1]. A recent study found gender differences in the prevalence and development of MetS in Chinese population with abdominal obesity, and that men have a more complex profile compared to women [2]. Modification of relevant lifestyle-related risk factors seems to be utterly important to prevent MetS, but the current situation in different parts of China is still unclear. A nationwide survey has shown that the prevalence of obesity in northern China was two-fold higher than that in southern China [3]. Another recent study in South China indicated that a large proportion of Chinese adults have the MetS and associated risk factors, emphasizing the urgent need to develop local strategies for its detection and management [4]. South China is not homogenous: Macau Special Administrative Region (Macau SAR) is a former Portuguese colony, with sovereignty returned to China in 1999, known today as the Las Vegas of Asia. The territory has undergone a rapid economic transition from a less industrialized area to a major city in the region. It has a population of 520 000 (95% of Chinese, 2% Portuguese and 1% Filipinos and 2% of other ethnicities). The information on prevalence of MetS in Macau is lacking. We therefore aimed to estimate the regional prevalence of MetS and associated factors among the population of Macau (18-44 years of age). This particular age was chosen as it represents a possible target for future health promotion in families.

This study examined gender differences in the prevalence of MetS, its components and some associated risk factors among the population of Macau. The age-adjusted prevalence of MetS was significantly higher in men than in women 10.5% and 3.7%, p < 0.001. The situation worsened dramatically during the ages of 35 – 40 years (Figure 1). In total 15.8% were overweight and 18.8% were obese (BMI ≥25). Overall, men had a higher prevalence in almost all of the metabolic components (Table 2). These results for the first time show the true situation in Macau SAR, confirming that MetS, a significant current problem in mainland China [4], has reached Macau. This is in accordance with the theory of thrifty genotype [16], stating that the transformation of a developing region to a developed municipal city might contribute to unhealthy habits, sedentary life style and other determinants of an obesogenic environment [16]. The real per capita GDP of Macau exceeds that of Hong Kong since year 2005, and the territory had been ranked the third in the Asia Pacific [17]. The neighbouring cities, such as Hong Kong, heavily influence Macau’s patterns of food consumption and physical activity habits, replacing the traditional health-enhancing practices. Macau’s booming tourist industry enhances the negative energy balance and sedentary lifestyle.

Lower education in the general population of China had been previously shown to be associated with higher risk of MetS in women, but not in men [18]. Our study shows that such lower education in both gender, and lower income in women are associated with a higher prevalence of MetS. Furthermore, women working full or part time had a lower rate of MetS. This difference seems to be more pronounced in Macau, as the majority of the population is employed in the casinos, where a higher education is not necessary. Additionally, being overweight among men in China, and particularly in Macau, has not been traditionally considered negative, but on the contrary, implies wealth and prosperity. Similar to findings from Korea, by Park et al., our study confirmed BMI being a sensitive modifiable risk factor among the associated risk factors for MetS [19].

The age range of our study population is 18 – 44 years; we particularly addressed the health status of adults of reproductive age, since their status will probably influence habits of the entire family. The main finding of this investigation is that Macau men (current or potential fathers) seem to have a higher risk to develop MetS, especially if they have lower education and are inactive. A recent study has confirmed a significantly increased risk of MetS in adolescents with a MetS parent [20]. Furthermore, a recent study in Sothern China [4] has reported that compared to women, men had a higher waist circumference, diastolic blood pressure, triglycerides, as well as a lower HDL-cholesterol level, although women had a higher prevalence of MetS than males (8.99% vs. 5.27%). These results cover the entire population, while the age in our study is 18-44 years, and may therefore be difficult to compare. Hong Kong survey 2003/2004 reported that overweight and obesity, hypertension, high blood cholesterol and diabetes were among the most prevalent chronic conditions with a higher proportion of males (42.5%) than females (35.9%) [9], but our findings reflect that the gender difference in Macau is much greater. Comparing to the general situation in greater China, the gender difference in the prevalence of different MetS components in Macau population differs from previously published findings. The prevalence Indices are lower and display different pattern. For example, the Inter-ASIA study, which is a national Chinese population sampling survey, indicated hypertension as the most common component of MetS in males (44.2%), whereas in females HDL-C was most common (46.5%) [3]. In our study, the most frequent component of MetS in women was abdominal obesity (24.2%), but in men, was hypertension (36.6%), followed by hypertriglyceridemia (26.7%) and abdominal obesity (21.9%). Findings of the Inter-ASIA study and this current study differ possibly due to the age of the participants. We included adults aged 18-44 years while the age Inter-ASIA study included older participants (35-74 years). We postulate that subgrouping of the population gives more detailed information of this particular age group.

The pattern of MetS components was more complex in males than in females. In contrast to recent research [2], our study did not show any gender difference in abdominal obesity and HDL. However, men had a significantly higher prevalence in the rest of the components. Thus, we find that males with MetS had a higher risk profile than females.

We have demonstrated that men have a higher risk of developing MetS. This gender difference could be partly explained by the younger pre-menopausal age of the women in our subpopulation, as the cardiovascular risk increases markedly after menopause [21]. The prevalence of MetS in pre-menopausal women, significantly lower than that in men, gradually surpasses males after menopause, as described in Hwang et al [22]. This could be the case in our study if women over 45 were included.

Once again, our study confirms the positive effect of exercise; mild level of physical activity seems to be enough. Although the IPAQ questionnaire refers to the last 7 days, the findings regarding the relationship between exercise and MetS in the Tables 3 and 4 should be interpreted with caution, since some people may have started to exercise after the emergence of MetS. Younger men are more physically active, gradually exercise less and catch up the levels of inactivity of females by the age of 35. Although it is commonly recognized that mothers spend more time with children, it is important to further investigate the father’s influence on children’s attitudes. As the study continues, it will be valuable to follow up the overweight fathers and their offspring, particularly boys, to explore the magnitude of this influence.

Some limitations of our study’s regional estimates should be mentioned.

First, the response rate of the MHS2006 is somewhat low. Second, the responded sample of the population might have been more health oriented than the ones who did not respond. Third, the results presented in this report lack information on diet, which is extensive. It is analysed and presented in a separate paper. Furthermore, information on smoking is lacking, it is one of the direct causes of coronary artery disease, indirectly inducing hypertension and diabetes in China [23]. Despite the newly launched National anti-smoking campaign and strict regulations in Macau, a big proportion of local population continues to smoke. Because the information on smoking was collected by a separate self-administrated form, containing other sensitive questions, this made it impossible to trace and analyse the smoking effect on our parameters. Finally, there were more women than men in our study, since females had a relatively higher response rate than males, which might cause a selection bias. Overall, as we determined the prevalence of MetS in Macau, we had difficulty in including more parameters in our logistic regression model, such as family history of hypertention, more detailed information on drinking, smoking etc, because at the times of the data collection, naturally less was known about the potential risk factors. This, in turn, underlines the importance of this report, making the comparison with the current situation possible. The cross-sectional study presented here does not allow us to draw any cause-effect relationship. Therefore, future prospective studies are needed to confirm the association between the suggested here and by others exposures and MetS among the population of Macau.

Despite these limitations, our study represents the first regional prevalence estimate of MetS, overweight and obesity among the adult Macau population. The study findings confirm that MetS continues to be a serious health hazard in this population. Furthermore, most preventive strategies today are general, not taking into consideration the situation locally and we believe that our data will help to fill this gap. This report not only serves as important baseline to track changes over time, but also provides clinicians and public health professionals with useful information essential for policy planning at regional and national levels.

Recent important study in China showed that although the average blood pressure levels and prevalence of hypertension among adults in the rural areas of China had dramatically increased during last decades, the awareness, treatment and control of hypertension remained low [24]. Similar to the suggestions by the authors, our study emphasizes that public health programs should be more specific, prioritizing, for example, prevention and control of hypertension, which will in turn reduce the occurrence of MetS and cardiovascular diseases.

Physical inactivity may enhance risk for MetS and elevate the risk for developing cardiovascular disease in people with MetS [25, 26]. With obvious rapid economic progress, Macau has been experiencing a lifestyle and dietary transition, which brought increasing inactivity and a shift towards high-fat, high-energy-density and low-fiber diet [25, 26]. Our study has also indicated that the prevalence of MetS was positively associated with inactivity. It therefore is logic that the health promotion programmes should focus on improving physical activity, especially in the male population of Macau. Potential interventions should determine, collect and analyze detailed data on the level of and quantity of physical activity among Macau population. Several steps can be taken to reduce the prevalence of potential risk factors contributing to the development of MetS in this population. Apart from dietary modifications, an increased physical activity may have implications to reduce this health burden. Implementation of these promotion strategies require support from the community. Thus, more studies aiming at examining the medical costs associated with MetS are needed. This will further emphasize how critical is the need for education and training of health care providers. Only then they will be able to have the knowledge necessary not only to treat the existent MetS patients but to develop effective MetS prevention programs on the community level.

In conclusion, we analyzed gender differences in the prevalence of MetS and its components in a Macau SAR population. We found the prevalence of MetS in this population was significantly higher in men than in women, especially with lower education and higher income status. This work lays the ground for understanding the recent obesity increase in the Macau population and is essential for the development of new policies, innovative programs and locally developed prevention strategies. Based on our results concerning gender differences in metabolic disease development, we suggest that emphasis of the programs related to MetS should be focused on early detection of metabolic risk factors, prevention, and interventions that should consist of gender-specific issues when addressing the family.