The metabolic syndrome in American Indians: the strong heart study

Blood DNA methylation and liver cancer in American Indians: evidence from the Strong Heart Study

PURPOSE

Liver cancer incidence among American Indians/Alaska Natives has risen over the past 20 years. Peripheral blood DNA methylation may be associated with liver cancer and could be used as a biomarker for cancer risk. We evaluated the association of blood DNA methylation with risk of liver cancer.

METHODS

We conducted a prospective cohort study in 2324 American Indians, between age 45 and 75 years, from Arizona, Oklahoma, North Dakota and South Dakota who participated in the Strong Heart Study between 1989 and 1991. Liver cancer deaths (n = 21) were ascertained using death certificates obtained through 2017. The mean follow-up duration (SD) for non-cases was 25.1 (5.6) years and for cases, 11.0 (8.8) years. DNA methylation was assessed from blood samples collected at baseline using MethylationEPIC BeadChip 850 K arrays. We used Cox regression models adjusted for age, sex, center, body mass index, low-density lipoprotein cholesterol, smoking, alcohol consumption, and immune cell proportions to examine the associations.

RESULTS

We identified 9 CpG sites associated with liver cancer. cg16057201 annotated to MRFAP1) was hypermethylated among cases vs. non-cases (hazard ratio (HR) for one standard deviation increase in methylation was 1.25 (95% CI 1.14, 1.37). The other eight CpGs were hypomethylated and the corresponding HRs (95% CI) ranged from 0.58 (0.44, 0.75) for cg04967787 (annotated to PPRC1) to 0.77 (0.67, 0.88) for cg08550308. We also assessed 7 differentially methylated CpG sites associated with liver cancer in previous studies. The adjusted HR for cg15079934 (annotated to LPS1) was 1.93 (95% CI 1.10, 3.39).

CONCLUSIONS

Blood DNA methylation may be associated with liver cancer mortality and may be altered during the development of liver cancer.

Metabolic Syndrome Among American Indian and Alaska Native Populations: Implications for Cardiovascular Health

PURPOSE OF REVIEW

The latest national data reports a 55% prevalence of metabolic syndrome in American Indian adults compared to 34.7% of the general US adult population. Metabolic syndrome is a strong predictor for diabetes, which is the leading cause of heart disease in American Indian and Alaska Native populations. Metabolic syndrome and associated risk factors disproportionately impact this population. We describe the presentation, etiology, and roles of structural racism and social determinants of health on metabolic syndrome.

RECENT FINDINGS

Much of what is known about metabolic syndrome in American Indian and Alaska Native populations comes from the Strong Heart Study as there is scant literature. American Indian and Alaska Native adults have an increased propensity towards metabolic syndrome as they are 1.1 times more likely to have high blood pressure, approximately three times more likely to have diabetes, and have higher rates of obesity compared with their non-Hispanic White counterparts. Culturally informed lifestyle and behavior interventions are promising approaches to address structural racism and social determinants of health that highly influence factors contributing to these rates. Among American Indian and Alaska Native populations, there is scarce updated literature evaluating the underlying causes of major risk factors for metabolic syndrome, and progression to cardiometabolic disease. As a result, the actual state of metabolic syndrome in this population is not well understood. Systemic and structural changes must occur to address the root causes of these disparities.

The Association of Arsenic Exposure and Arsenic Metabolism With the Metabolic Syndrome and Its Individual Components: Prospective Evidence From the Strong Heart Family Study

Inorganic arsenic exposure is ubiquitous, and both exposure and interindividual differences in its metabolism have been associated with cardiometabolic risk. However, the associations of arsenic exposure and arsenic metabolism with the metabolic syndrome (MetS) and its individual components are relatively unknown. We used Poisson regression with robust variance to evaluate the associations of baseline arsenic exposure (urinary arsenic levels) and metabolism (relative percentage of arsenic species over their sum) with incident MetS and its individual components (elevated waist circumference, elevated triglycerides, reduced high-density lipoprotein cholesterol, hypertension, and elevated fasting plasma glucose) in 1,047 participants from the Strong Heart Family Study, a prospective family-based cohort study in American Indian communities (baseline visits were held in 1998-1999 and 2001-2003, follow-up visits in 2001-2003 and 2006-2009). Over the course of follow-up, 32% of participants developed MetS. An interquartile-range increase in arsenic exposure was associated with a 1.19-fold (95% confidence interval: 1.01, 1.41) greater risk of elevated fasting plasma glucose concentration but not with other individual components of the MetS or MetS overall. Arsenic metabolism, specifically lower percentage of monomethylarsonic acid and higher percentage of dimethylarsinic acid, was associated with higher risk of overall MetS and elevated waist circumference but not with any other MetS component. These findings support the hypothesis that there are contrasting and independent associations of arsenic exposure and arsenic metabolism with metabolic outcomes which may contribute to overall diabetes risk.

Prevalence of metabolic syndrome and diabetes mellitus in Sami and Norwegian populations. The SAMINOR-a cross-sectional study

OBJECTIVES

Metabolic syndrome (MetS) is recognised as a reliable long-term predictor of adverse health outcomes. Elevated prevalence rates of MetS and chronic lifestyle diseases have been documented in different indigenous groups. We aimed to evaluate the prevalence of MetS and diabetes mellitus in relation to ethnicity in Northern Norway. In addition, we discussed different cut-off values for waist circumference (WC) and what impact this has on the prevalence of MetS.

MATERIALS AND METHODS

SAMINOR is a population-based study of health and living conditions in areas home to Sami and non-Sami populations. The survey was carried out in 2003-2004. All eligible residents in specific age groups were invited. In total, 16,538 males and females aged 36-79 years participated and gave informed consent for medical research.

RESULTS

This study involved a total of 7822 female and 7290 male participants. Sami affiliation was reported by 5141 participants (34%). The prevalence of MetS was high in both ethnic groups independent of which WC cut-off value was used. No ethnic differences in prevalence of diabetes mellitus were demonstrated. However, ethnicity appeared to affect diabetes treatment, which was more prevalent among Sami than non-Sami women.

CONCLUSIONS

In this study, there was no ethnic difference in diabetes prevalence, but ethnicity appeared to affect diabetes treatment. Tablet treatment was more commonly in use among Sami women than among non-Sami women. We demonstrated a high share of negative metabolic components. These metabolic components have important health implications. Therefore, determining preventive initiatives is important in the primary and specialist healthcare system. These initiatives must be made culture and linguistic specific, in order to reduce differences and improve health status in the whole population.

Incidence of metabolic syndrome and related diseases in the Khisêdjê indigenous people of the Xingu, Central Brazil, from 1999-2000 to 2010-2011

The aim of this study was to identify the incidence of metabolic syndrome and related diseases in the Khisêdjê population living in the Xingu Indigenous Park, Mato Grosso State, Brazil, from 1999‐2000 to 2010‐2011. The study included 78 individuals aged ≥20 years. Data were analyzed using Student t test, linear regression, and Poisson regression. In 10 years of follow-up, cumulative incidence rates were 37.5% for metabolic syndrome, 47.4% for hypetriglyceridemia, 38.9% for arterial hypertension, 32% for central obesity, 30.4% for excess weight, 29.1% for hypercholesterolemia, 25% for low HDLc, 10.4% for high LDLc, and 2.9% for diabetes mellitus. Age proved to be a risk factor for incidence of hypertension, diabetes, and elevated LDLc, regardless of gender; male gender was a protective factor against incidence of central obesity, independently of age. The study showed deterioration of most target health indicators and exposure of the Khisêdjê to high cardiometabolic risk. These results may be related to changes in traditional lifestyle.

Leading causes of death and all-cause mortality in American Indians and Alaska Natives

OBJECTIVES

We present regional patterns and trends in all-cause mortality and leading causes of death in American Indians and Alaska Natives (AI/ANs).

METHODS

US National Death Index records were linked with Indian Health Service (IHS) registration records to identify AI/AN deaths misclassified as non-AI/AN. We analyzed temporal trends for 1990 to 2009 and comparisons between non-Hispanic AI/AN and non-Hispanic White persons by geographic region for 1999 to 2009. Results focus on IHS Contract Health Service Delivery Area counties in which less race misclassification occurs.

RESULTS

From 1990 to 2009 AI/AN persons did not experience the significant decreases in all-cause mortality seen for Whites. For 1999 to 2009 the all-cause death rate in CHSDA counties for AI/AN persons was 46% more than that for Whites. Death rates for AI/AN persons varied as much as 50% among regions. Except for heart disease and cancer, subsequent ranking of specific causes of death differed considerably between AI/AN and White persons.

CONCLUSIONS

AI/AN populations continue to experience much higher death rates than Whites. Patterns of mortality are strongly influenced by the high incidence of diabetes, smoking prevalence, problem drinking, and social determinants. Much of the observed excess mortality can be addressed through known public health interventions.

Cardiovascular risk factors in children and adolescents living in an urban area of Southeast of Brazil: Ouro Preto Study

This study aims to identify risk factors for cardiovascular disorders in schoolchildren living in Ouro Preto City, Brazil. A cross-sectional study was carried out in a population-based sampling of schoolchildren (6-14 years old), randomly selected and stratified by the proportion of students according to age and gender in each schools of the city. Biochemical, clinical and anthropometric variables as well as physical activity and family history were used in a logistic regression model for obesity or arterial hypertension. Out of 780 schoolchildren sampled, the risk of obesity was greater in subjects presenting high triglyceride and low high density lipoprotein-cholesterol levels, and those whose parents were obese, while the risk of hypertension was high in obese subjects and those who presented low birth weight. It was observed that 44.4% of the schoolchildren were exposed to two or three cardiovascular disease (CVD) risk factors and 8.2% were exposed to four or six factors. These findings should be considered in preventive measures to reduce the future risk for CVD among schoolchildren in Brazil.

Metabolic syndrome and its components as predictors of incident type 2 diabetes mellitus in an Aboriginal community

BACKGROUND

Risk factors for type 2 diabetes remain poorly characterized among Aboriginal Canadians. We aimed to determine the incidence of type 2 diabetes in an Aboriginal community and to evaluate prospective associations with metabolic syndrome and its components.

METHODS

Of 606 participants in the Sandy Lake Health and Diabetes Project from 1993 to 1995 who were free of diabetes at baseline, 540 (89.1%) participated in 10-year follow-up assessments. Baseline anthropometry, blood pressure, fasting insulin and serum lipid levels were measured. Fasting and 2-hour postload glucose levels were obtained at follow-up to determine incident cases of type 2 diabetes.

RESULTS

The 10-year cumulative incidence of diabetes was 17.5%. High adiposity, dyslipidemia, hyperglycemia, hyperinsulinemia and hypertension at baseline were associated with an increased risk of diabetes after adjustment for age and sex (all p < or = 0.03). Metabolic syndrome had high specificity (75%-88%) and high negative predictive value (85%-87%) to correctly detect diabetes-free individuals at follow-up. It had low sensitivity (26%-48%) and low positive predictive value (29%-32%) to detect future diabetes. Metabolic syndrome at baseline was associated with incident diabetes after adjustment for age and sex, regardless of whether the syndrome was defined using the National Cholesterol Education Program criteria (odds ratio [OR] 2.03, 95% confidence interval [CI] 1.10-3.75) or the International Diabetes Federation criteria (OR 2.14, 95% CI 1.29-3.55). The association was to the same degree as that for impaired glucose tolerance assessed using the oral glucose tolerance test (OR 2.87, 95% CI 1.52-5.40; p > 0.05 for comparison of C statistics).

INTERPRETATION

Metabolic syndrome and its components can be identified with readily available clinical measures. As such, the syndrome may be useful for identifying individuals at risk of type 2 diabetes in remote Aboriginal communities.