Chronic diseases are the largest cause of death in the world. The leading chronic diseases—cardiovascular disease, cancer, chronic respiratory disease, and diabetes—caused 57 million deaths worldwide [1]. Furthermore, despite a growing number of epidemiological evidences, such as the economic impact, the global response to the problem remains ineffective. The chronic disease problem is not limited to the developing regions put; it affects the entire world [1].

According to U.S. Department of Health and Human Services [2] approximately 45 % of the American population is diagnosed with at least one chronic disease. It was further stated by Waters and Graf [3], that one or more of five chronic diseases cause two-thirds of all deaths: heart disease, cancer, stroke, chronic obstructive pulmonary disease, and diabetes. There is growing evidence that the presence of one chronic condition has a negative impact on the risk of developing others, particularly as people age Researchers stated that health care costs for chronic diseases such as heart disease, cancer, diabetes, and Alzheimer's disease totaled $1.1 trillion in 2016 and expected to double by 2020. The total economic impact of this was $3.7 trillion including lost economic productivity. This was equivalent to nearly 20% of the U.S. gross domestic product.

Metabolic syndrome (MetS) is a combination of risk indicators that appear to promote the development of chronic diseases [4]. MetS is known as a consistent long-term predictor of adverse health outcomes [5]. According to the National Heart Lung and Blood Institute [6], MetS is described as a group of risk factors that increase the chance of having cardiovascular conditions and other health problems such as diabetes and stroke. Five conditions are involved in the diagnosis of MetS: elevated waist circumference, elevated triglycerides, low High-density lipoprotein (HDL-C) cholesterol, elevated blood pressure and elevated fasting glucose. For a diagnosis of MetS, patients must present with at least three of these conditions [7].

A study by Moore et al. [8] analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 1988 through 2012. They found that MetS prevalence increased from 1988 to 2012 for every sociodemographic group. The report further stated that by 2012 more than a third of US adults met the definition and criteria for MetS. During the entire study period, the largest increase in the prevalence of MetS was observed among African- American men (55%), then White women (44%), and African-American women (41%). The smallest increase was observed among Hispanic women (2%). MetS prevalence increased among White men by 31% and increased among Hispanic men by 12.5% [8].

There are many risk factors that contribute to or influence the onset of MetS.  Research by Kaur [9] found that genetics, diet, level of physical activity, smoking, family history of diabetes, and level of education all influenced the prevalence of MetS. Also, it was reported that people who are diagnosed with MetS are twice as likely to develop cardiovascular disease (CVD), and about five times the risk for type 2 diabetes mellitus (T2DM) when compared with those without the syndrome.

Overweight and obesity are health issues that also contribute significantly to MetS through certain pathophysiological mechanisms [9]. It was stated by many researchers that chronic inflammation associated with excess adipose tissue may explain the development of obesity-related pathologies, such as T2DM and CVD [10,11]. Other studies demonstrated that management of weight and engaging in an appropriate level of physical activity might prevent the transition from impaired glucose tolerance to T2DM, and help to reduce MetS [12].  According to González et al [13] several studies concluded that several health issues are associated with high sedentary time. For example, sedentary behavior has positive associations with an increased risk of T2DM, CVD mortality and cancer [14].

Sleep disorder is a major public health issue and it is linked to the cluster of conditions associated with increased risk of obesity, insulin resistance (IR), and MetS or components of MetS, among adult and pediatric populations [15]. According to Medic et al. [16] sleep disorders are associated with health risk problems such as increased body mass index, poor physical health, substance abuse, depression, and negative alteration in metabolic and endocrine functions. 

There is growing evidence that lifestyle changes can help to reduce the growing rate of MetS in the population. According to Pérez-Martínez et al [17] physical activity and consumption of the Mediterranean diet pattern can help to control or prevent the factors that contribute to MetS. It was recommended that the ideal dietary pattern should have increased levels of unsaturated fat, cereals, whole grains, fruits, vegetables, nuts, fish, and low-fat dairy products, as well as moderate consumption of alcohol. Other dietary patterns such as; Dietary Approaches to Stop Hypertension (DASH), new Nordic, and vegetarian diets have been proposed as alternatives for preventing MetS [17]. The first hypothesis tested was that African Americans and Hispanics would be more likely to have higher risk of the following consequences of MetS than Whites:  Heart attack, coronary heart disease, stroke, breast cancer, prostate cancers, diabetes, prediabetes, overweight and obesity. The hypothesis was supported that African Americans and Hispanics would be more likely to have higher risk of heart attack, breast cancers, diabetes, prediabetes, overweight and obesity than Whites. However, the hypothesis was not supported that African Americans and Hispanics would be more likely to have higher risk of coronary heart disease, stroke and prostate cancers than Whites.

Secondly, it was noticed that subjects who diagnosed with MetS criteria would be more likely to have higher risk of the following consequences: heart attack, coronary heart disease, stroke, breast cancer, prostate cancers, T2DM, prediabetes, overweight and obesity. Therefore, the hypothesis was supported that subjects who were diagnosed with MetS criteria would be more likely to have higher risk of stroke, diabetes, prediabetes, prostate cancer, overweight and obesity. However, the hypothesis was not supported that subjects who were diagnosed with MetS criteria would be more likely to have higher risk of Heart attack, coronary heart disease and breast cancer.

The proposed study used data abstracted from the National Health and Nutrition Examination Survey (NHANES) 2015-2016. The following variables were utilized: sociodemographic data (age, gender, marital status, educational level and household income);  the criteria for MetS diagnosis (levels of blood pressure, fasting plasma blood glucose, blood triglyceride, HDL-cholesterol, and waist circumference); and the consequences of MetS (coronary heart disease, heart attack, stroke, breast cancer, prostate cancer, diabetes and prediabetes, overweight and obesity). The sample was made up of 1,562 African Americans, Hispanics and Whites aged 40 years or more, and of both genders. Subjects with incomplete waist circumference, blood pressure, fasting blood glucose, and lipid profile data, and pregnant women were excluded. The data were analyzed using SUDAAN software (RTI international, INC., Research Triangle Park, North Carolina). SUDAAN is the recommended software for analysis of NHANES data. The relationships of MetS and its individual components were compared among the three ethnics groups using chi-square and t tests. The significance level used was 5%.

Of the data collected in NHANES 2015-2016, the following were utilized:

1. Sociodemographic data (age, gender, marital status, educational level and household income);
2. The criteria for MetS diagnosis (levels of blood pressure, fasting plasma blood glucose, blood triglyceride, HDL-cholesterol, and waist circumference,);
3. Consequences of MetS (Heart Attack, Coronary Heart Disease, Breast Cancer, Prostate Cancer, Diabetes, Prediabetes, Stroke, Overweight and Obesity).
4. Descriptions of how these data were collected follow.

Table 1. Socio-demographic Characteristics

Table 1 shows data on the socio-demographic characteristics of the subjects. The majority of the subjects (78.0%) were aged between 40 and 69 years.  The percentage of females was higher than males. In terms of race/ethnicity, Non-Hispanic White had the highest percentage (approximately 37%), followed by Non-Hispanic Blacks, other Hispanics and Mexican Americans.

Table 2. Socio-demographic Characteristics

Table 2 shows the educational level and annual household income frequencies. In terms of educational level, the majority of the subjects (75.2%) had educational levels between high school graduate/GED, and college graduate or above. Annual household incomes were highly variable, the most common annual household incomes being under $20,000, $20.000- 34,999, $35.000-54,999 and $100,000 or more.

Table 3. MetS Status by Ethnicity

Table 3 shows MetS status by ethnicity. The prevalence of MetS was highest in Hispanics, followed by Whites, and African Americans.

Table 4. Doctor or Other Health Professional Diagnoses of Diabetes and Prediabetes by MetS and Ethnicity

Table 4 shows that among the subjects with MetS, the highest prevalence of diabetes diagnosed by doctors or other health professionals was in African Americans (35.6%), followed by Hispanics (32.0%), and Whites (25.5%). A similar pattern was seen for diagnoses of borderline diabetes. For diagnoses of prediabetes, the highest prevalence was among Hispanics (26.5%), followed by Whites (18.1%), and African Americans (17.5%). In all ethnic groups, the prevalence of both conditions was lower in the subjects who did not have MetS.

¹A probability level below 0.05 indicates a significant relationship between the two variables

Table 5. Relationships of Doctor or Other Health Professional Diagnoses of Diabetes and Prediabetes to MetSby Ethnicity

Table 5 shows that in all ethnic groups who have Mets are significantly more likely to be diabetic, while Hispanics with Mets are significantly more likely to be diagnosed with prediabetic. In African Americans and Whites there was no significant relationship between MetS and prediabetes.

Table 6. Doctor or Other Health Professional Diagnoses of Coronary Heart Disease, Heart Attack, and Stroke by MetS and Ethnicity

Table 6 shows that among the subjects with MetS, the highest prevalence of coronary heart disease diagnosed by doctors or other health professionals was in Whites (7.9%), followed by African Americans (7.1%), and Hispanics (6.3%). For diagnoses of heart attack, the highest prevalence was among Hispanic (7.8 %), followed by White (6.5%) and African American (5.9%). For diagnoses of stroke, the highest prevalence was among Whites (7.4%), followed by African Americans (5.9%) and Hispanics (3.4%). In all ethnic groups, the prevalence of all conditions was lower in the subjects who did not have MetS.

¹A probability level below 0.05 indicates a significant relationship between the two variables

Table 7. Relationships of Doctor or Other Health Professional Diagnoses of Coronary Heart Disease, Heart Attack, and Stroke to MetSby Ethnicity

Table 7 shows no significant relationships of MetS to coronary heart disease, heart attack and stroke in all ethnic groups.

¹BMI 18.5 kg/m² 2BMI 18.5-24.9 kg/m²

³BMI 25.0-29.9 kg/m² 4BMI≥30.0 kg/m²

Table 8.BMI Category by MetS and Ethnicity

Table 8 shows that among the subjects with MetS, the highest prevalence of overweight diagnosed by doctors or other health professionals was in Hispanics (32.5%), followed by Whites (31.0%), and African Americans (24.8%). For obesity, the highest prevalence was among African Americans (74.3%), followed by Hispanics (63.6%), and Whites (60.2%).

¹A probability level below 0.05 indicates a significant relationship between the two variables

Table 9. Relationship of BMI Category to MetSby Ethnicity

Table 9 shows that in all ethnic groups those who have Mets are significantly more likely to be overweight or obese.

Table 10.Diagnoses of Breast Cancer and Prostate Cancer to MetS by Ethnicity

Table 10 shows that among the subjects with MetS, the highest prevalence of diagnosed breast cancer was in Hispanics (3.9%), followed by African Americans (2.0%), and Whites (1.9 %). For diagnoses of prostate cancer, the highest prevalence was among Whites (2.8%), followed by African Americans (2.0%) and Hispanics (1.0%). In all ethnic groups, the prevalence of both conditions was lower in the subjects who did not have MetS (Table 1-Table 10).

In conclusion, this study demonstrated that the first objective was to compare Heart attack, coronary heart disease, stroke, breast cancer, prostate cancers, diabetes, prediabetes, overweight and obesity in African Americans, Hispanics and Whites.

Whereas, it was found that African Americans and Hispanics would be more likely to have higher risk of heart attack, breast cancers, diabetes, prediabetes, overweight and obesity than Whites. However, African Americans and Hispanics would not be more likely to have higher risk of coronary heart disease, stroke and prostate cancers than Whites.

This study also demonstrated that the second objective was to evaluate the relationships of the individual components of MetS to Heart attack, coronary heart disease, stroke, breast cancer, prostate cancers, diabetes, prediabetes, overweight and obesity in African Americans, Hispanics and Whites.

Whereas, it was found that subjects who were diagnosed with MetS criteria would be more likely to have higher risk of stroke, diabetes, prediabetes, overweight and obesity. However, it was found that subjects who were diagnosed with MetS criteria would not be more likely to have higher risk of Coronary Heart Disease, Heart attack, Stroke, Breast cancer and Prostate cancer.

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