Farming and adiposity in Samoan adults

Accelerometer-Based Estimates of Physical Activity and Sedentary Time Among Samoan Adults

BACKGROUND

The prevalence of obesity-related cardiometabolic disease in Samoa is among the highest globally. While physical activity is a modifiable risk factor for obesity-related disease, little is known about physical activity levels among adult Samoans. Using wrist-worn accelerometer-based devices, this study aimed to characterize physical activity among Samoan adults.

METHODS

Samoan adults (n = 385; 55% female, mean [SD] age 52 [10] y) wore Actigraph GT3X+ devices for 7 to 10 days. General linear models were used to examine mean daily minutes of sedentary time, light physical activity, and moderate to vigorous physical activity by various participant characteristics.

RESULTS

Time spent in moderate to vigorous physical activity did not differ statistically between men (88 [5] min; 95% confidence interval [CI], 80-97) and women (78 [4] min; 95% CI, 70-86; P = .08). Women, however, spent more time than men in light physical activity: 380 (7) minutes (95% CI, 367-393) versus 344 (7) minutes (95% CI, 329-358; P < .001). While there were no differences in physical activity by census region, education, or occupation among women, men in urban areas spent significantly less time in moderate to vigorous physical activity than those in peri-urban and rural areas (P = .015). Women with class II/III obesity spent more time in sedentary activities than those with healthy weight or overweight/class I obesity (P = .048).

CONCLUSIONS

This study characterizes physical activity among Samoan adults and highlights variation by sex, urbanicity, and weight status. In providing initial device-measured estimates of physical activity in Samoa, this analysis establishes a baseline from which the success of future attempts to intervene on physical activity may be assessed.

The milk study protocol: A longitudinal, prospective cohort study of the relationship between human milk metabolic hormone concentration, maternal body composition, and early growth and satiety development in Samoan infants aged 1-4 months

BACKGROUND

Current research suggests that energy transfer through human milk influences infant nutritional development and initiates metabolic programming, influencing eating patterns into adulthood. To date, this research has predominantly been conducted among women in high income settings and/or among undernourished women. We will investigate the relationship between maternal body composition, metabolic hormones in human milk, and infant satiety to explore mechanisms of developmental satiety programming and implications for early infant growth and body composition in Samoans; a population at high risk and prevalence for overweight and obesity. Our aims are (1) to examine how maternal body composition influences metabolic hormone transfer from mother to infant through human milk, and (2) to examine the influences of maternal metabolic hormone transfer and infant feeding patterns on early infant growth and satiety.

METHODS

We will examine temporal changes in hormone transfers to infants through human milk in a prospective longitudinal cohort of n = 80 Samoan mother-infant dyads. Data will be collected at three time points (1, 3, & 4 months postpartum). At each study visit we will collect human milk and fingerpick blood samples from breastfeeding mother-infant dyads to measure the hormones leptin, ghrelin, and adiponectin. Additionally, we will obtain body composition measurements from the dyad, observe breastfeeding behavior, conduct semi-structured interviews, and use questionnaires to document infant hunger and feeding cues and satiety responsiveness. Descriptive statistics, univariate and multivariate analyses will be conducted to address each aim.

DISCUSSION

This research is designed to advance our understanding of variation in the developmental programming of satiety and implications for early infant growth and body composition. The use of a prospective longitudinal cohort alongside data collection that utilizes a mixed methods approach will allow us to capture a more accurate representation on both biological and cultural variables at play in a population at high risk of overweight and obesity.

Association between age at menarche and cardiometabolic risk among Samoan adults

OBJECTIVES

Recent studies suggest that early menarche may increase cardiometabolic morbidity and mortality. Yet few studies have examined this association in the Pacific Islands, where obesity prevalence is among the highest globally. We sought to examine associations between age at menarche and cardiometabolic risk in Samoa.

METHODS

Participants were from the Soifua Manuia study (n = 285, age 32-72 years) conducted in Samoa from 2017 to 2019. Logistic regressions were conducted to estimate odds of obesity, hypertension, diabetes, dyslipidemia, and metabolic syndrome per one-year increase in age at menarche. Linear regressions were conducted to examine associations between age at menarche and continuous measures of adiposity, blood pressure, insulin resistance, and serum lipids.

RESULTS

Median age at menarche was 14 years (IQR = 2). After controlling for relevant covariates, each one-year increase in age at menarche was associated with a 15% decrease (OR = 0.85, 95% CI: 0.72-1.01, p = .067) in odds of hypertension, but a 21% increase (OR = 1.21, 95% CI: 1.01-1.45, p = .044) in odds of diabetes and 18% increase (OR = 1.18, 95% CI: 0.98-1.42, p = .081) in odds of high total cholesterol. Each additional year in age at menarche was associated with a 1.60 ± 0.52 kg (p = .002) decrease in lean mass and 1.56 ± 0.51 kg (p = .003) decrease in fat-free mass.

CONCLUSIONS

Associations between age at menarche and cardiometabolic risk may be population-specific and are likely influenced by both current and historical nutritional and epidemiological contexts. Prospective studies are needed to clarify the role of childhood adiposity and other early life exposures on age at menarche and subsequent cardiometabolic risk.

Validity of anthropometric equation-based estimators of fat mass in Samoan adults

INTRODUCTION

In 1999, a set of highly accurate Polynesian-specific equations to estimate adult body fat from non-invasive field measures of age, sex, height, and weight (Equation 1), age, sex, height, weight, and bioelectrical impedance analysis (BIA) resistance (Equation 2), and age, sex, height, weight, and the sum of two skinfold thicknesses (Equation 3) were published. The purpose of this study was to evaluate the performance of the equation-based estimators in a sample of Samoan adults recruited 20 years later between 2017 and 2019.

METHODS

Age, sex, height, weight, BIA resistance, skinfold thickness, and fat mass as measured using dual energy x-ray absorptiometry (DXA) were available for 432 Samoan adults (mean age 50.9 years, 56% female) seen in 2017/2019. We compared equation-derived fat mass and DXA-derived fat mass using scatterplots and Pearson correlation coefficients. We then updated the equation coefficient estimates in a training set (2/3 of the sample) and evaluated the performance of the updated equations in a testing set (the remaining 1/3 of the sample).

RESULTS

Equation-derived fat mass was strongly correlated with DXA-derived fat mass for Equation (1) (r2  = 0.95, n = 432), Equation (2) (r2  = 0.97, n = 425), and Equation (3) (r2  = 0.95, n = 426). Updating the equation coefficient estimates resulted in mostly similar coefficients and nearly identical testing set performance for Equation (1) (r2  = 0.96, n = 153), Equation (2) (r2  = 0.98, n = 150), and Equation (3) (r2  = 0.96, n = 150).

CONCLUSIONS

The Polynesian-specific body fat estimation equations remained stable despite changing social and environmental factors and marked increase in obesity prevalence in Samoa.

Multivariate analysis of a missense variant in CREBRF reveals associations with measures of adiposity in people of Polynesian ancestries

The minor allele of rs373863828, a missense variant in CREB3 Regulatory Factor, is associated with several cardiometabolic phenotypes in Polynesian peoples. To better understand the variant, we tested the association of rs373863828 with a panel of correlated phenotypes (body mass index [BMI], weight, height, HDL cholesterol, triglycerides, and total cholesterol) using multivariate Bayesian association and network analyses in a Samoa cohort (n = 1632), Aotearoa New Zealand cohort (n = 1419), and combined cohort (n = 2976). An expanded set of phenotypes (adding estimated fat and fat-free mass, abdominal circumference, hip circumference, and abdominal-hip ratio) was tested in the Samoa cohort (n = 1496). In the Samoa cohort, we observed significant associations (log10 Bayes Factor [BF] ≥ 5.0) between rs373863828 and the overall phenotype panel (8.81), weight (8.30), and BMI (6.42). In the Aotearoa New Zealand cohort, we observed suggestive associations (1.5 < log10 BF < 5) between rs373863828 and the overall phenotype panel (4.60), weight (3.27), and BMI (1.80). In the combined cohort, we observed concordant signals with larger log10 BFs. In the Samoa-specific expanded phenotype analyses, we also observed significant associations between rs373863828 and fat mass (5.65), abdominal circumference (5.34), and hip circumference (5.09). Bayesian networks provided evidence for a direct association of rs373863828 with weight and indirect associations with height and BMI.

The missense variant, rs373863828, in CREBRF plays a role in longitudinal changes in body mass index in Samoans

OBJECTIVE

A missense variant, rs373863828, in CREBRF is associated with obesity in Polynesians. We investigate whether rs373863828 and other factors are associated with body mass index (BMI) rate-of-change between 2010 and 2017-19 in Samoans.

METHODS

We used sex-stratified models to test whether BMI rate-of-change was associated with rs373863828, baseline BMI, age, residence, physical activity, and household asset score in a cohort study of 480 Samoan adults measured in both 2010 (mean age 43.8 years) and 2017-19.

RESULTS

Mean BMI increased from 32.1 to 33.5 kg/m² in males (n = 220, p = 1.3 ×10^-8) and from 35.9 to 37.8 kg/m² in females (n = 260, p = 1.2 ×10^-13). In females, the A allele was associated with a higher rate-of-change (0.150 kg/m²/year/allele, p = 1.7 ×10^-4). Across 10-year age groups, mean BMI rate-of-change was lower in older participants. The BMI rate of change differed by genotype: it was, in females with AA genotype, approximately half that seen in GG and AG participants. In females lower baseline household asset scores were associated with a higher rate-of-change (p = 0.002).

CONCLUSIONS

In Samoans, the minor A allele of rs373863828 is associated with an increased rate-of-change in BMI in females. On average, BMI of females with the AA genotype increased 0.30 kg/m²/year more than of those with the GG genotype.

Cascades of diabetes and hypertension care in Samoa: Identifying gaps in the diagnosis, treatment, and control continuum - a cross-sectional study

BACKGROUND

Samoa is a Pacific Island country facing one of the highest burdens of non-communicable disease globally.

METHODS

In this study, we apply a cascade-of-care approach to understand gaps in the awareness, treatment, and control cascade of diabetes and hypertension in a cross-sectional, convenience sample of 703 young, high-risk Samoan adults (29.5-50.9 years).

FINDINGS

Non-communicable diseases were prevalent in the study sample: 19.5% (95% CI: 16.6%-22.7%) of participants had diabetes; 47.6% (95% CI: 43.7%-51.4%) presented with pre-diabetes or diabetes; 31.0% (95% CI: 27.5%-34.6%) had hypertension; and nearly 90% (95% CI: 86.7%-91.5%) had overweight or obesity. Among those with diabetes and hypertension, only 20.5% (95% CI: 13.9%-28.4%) and 11.8% (95% CI: 7.8%-16.9%) of participants were aware of their condition, respectively. Only 0.8% (95% CI: 0.0%-4.2%) of all participants with diabetes had achieved glycemic control; only 2.8% (95% CI: 1.1%-6.1%) of those with hypertension achieved control.

INTERPRETATION

We found a significant burden of diabetes and hypertension in Samoa, exceeding the recent prevalence estimates of other low- to middle-income countries by nearly two-fold. A severe unmet need in both detection and subsequent control and monitoring of these chronic conditions exists. Our results suggest that the initial diagnosis and surveillance stage in the cascade of care for chronic conditions should be a major focus of primary care efforts; national screening campaigns and programs that leverage village and district nurses to deliver community-based primary care may significantly impact gap closure in the NCD cascade.

FUNDING

This study was supported by the U.S. National Institutes of Health R01HL140570 (PIs: McGarvey and DeLany); AR was supported by NIH FIC D43TW010540; HK and AR-C were supported by the Minority Health and Health Disparities International Research Training (MHIRT) Program at Brown University, NIH Grant # 5T37MD008655.

Life course socioeconomic position and body composition in adulthood: a systematic review and narrative synthesis

INTRODUCTION

Multiple systematic reviews have investigated the relation between socioeconomic position (SEP) and body mass index (BMI) throughout the life course. However, BMI does not capture quantity and distribution of fat and muscle, which are better indicators of obesity than BMI, and have been independently linked to adverse health outcomes. Less is known about the relation between SEP and body composition, and the literature has not been reviewed. We therefore systematically reviewed the literature on the association between life course SEP and body composition in adulthood.

METHODS

A protocol was registered on PROSPERO (CRD42019119937), and the review followed PRISMA guidelines. An electronic search of three databases (MEDLINE, Embase Classic + Embase and SPORTDiscus) was conducted. Original studies in the English language were included that examine the association between any recognised measure of SEP at any age and body composition (fat mass, fat-free mass, ratio and distribution) in adulthood, measured using a direct technique, i.e., not an anthropometric measure. A narrative synthesis was conducted.

RESULTS

A total of 47 papers were included in the final review, none were from low-income countries (LICs). Greater advantage in childhood and adulthood was associated with lower fat levels in high-income countries (HICs). Associations in the opposite direction were found exclusively in middle-income countries (MICs). No studies in MICs reported associations for childhood SEP. For measures of lean mass, the majority of papers reported no association, or greater advantage in adulthood associated with higher lean mass, with little variation between HICs and MICs. Associations in HICs are more often observed in women than men.

CONCLUSION

The results indicate that fat measures follow similar patterns to those seen for BMI, and that women in HICs are more likely to experience inequalities in both fat and lean measures. Further research in LICs and MICs is needed.

Associations between socioeconomic resources and adiposity traits in adults: Evidence from Samoa

In low- and middle-income countries, earlier in economic development, obesity tends to be more prevalent in high socioeconomic resource groups compared to low. Later in development, the distribution of obesity tends to show the opposite pattern, becoming more prevalent in those with low socioeconomic resources. This shift in obesity prevalence tends to occur between a gross national income per capita (GNI) of US$1,000 to $4,000 dollars. Whether a similar pattern occurs in Pacific Island countries has not been well documented. In Samoa, the GNI rose to US$3,200 dollars in 2010 at which time over 80% of adults were overweight or obese. We aimed to understand the association of socioeconomic resources, assessed by household assets, with adult body mass index (BMI) and abdominal circumference (AC) in Samoa. Data were from a genome-wide association study for obesity among 3,370 Samoans aged 24.5-<65 years in 2010. Household asset scores were calculated based on ownership of consumer durables, housing construction, and access to basic services. Sex-stratified multivariate linear regressions were used to assess adiposity trait differences by household asset ownership, after controlling for age, education, and household urbanicity. Higher asset ownership was associated with higher BMI and AC and the positive relationship remained robust after controlling for potential confounders. Despite significant economic growth preceding the year 2010 in Samoa, the obesity burden had not shifted to low socioeconomic groups in a similar way that has been observed in countries further along in the economic transition. The mechanism by which socioeconomic resources influence adiposity is complex and may be particularly complicated in Samoa by migrant remittances received both as cash and household assets. Social and physical environments may constrain the positive health behavior change necessary to reduce obesity even in the context of high socioeconomic position, a situation that requires further investigation.

Dietary Patterns Are Associated with Metabolic Outcomes among Adult Samoans in a Cross-Sectional Study

Background: The Samoan population has been undergoing a nutrition transition toward more imported and processed foods and a more sedentary lifestyle.Objectives: We aimed to identify dietary patterns in Samoa and to evaluate their associations with metabolic outcomes.Methods: The sample of this cross-sectional study includes 2774 Samoan adults recruited in 2010 (1104 with metabolic syndrome compared with 1670 without). Principal component analysis on food items from a 104-item food-frequency questionnaire was used to identify dietary patterns. Adjusted least squares means of each component of metabolic syndrome were estimated by quintiles of factor scores for each dietary pattern. Metabolic syndrome status was regressed on quintiles of scores by using log-binomial models to obtain prevalence ratios.Results: We identified a modern pattern, a mixed-traditional pattern, and a mixed-modern pattern. The modern pattern included a high intake of imported and processed foods, including pizza, cheeseburgers, margarine, sugary drinks, desserts, snacks, egg products, noodles, nuts, breads, and cakes and a low intake of traditional agricultural products and fish. The mixed-traditional pattern had a high intake of neotraditional foods, including fruits, vegetables, soup, poultry, and fish, and imported and processed foods, including dairy products, breads, and cakes. The mixed-modern pattern was loaded with imported and processed foods, including pizza, cheeseburgers, red meat, egg products, noodles, and grains, but also with neotraditional foods, such as seafood and coconut. It also included a low intake of fish, tea, coffee, soup, and traditional agricultural staples. Higher adherence to the mixed-modern pattern was associated with lower abdominal circumference (P-trend < 0.0001), lower serum triglycerides (P-trend = 0.03), and higher serum HDL cholesterol (P-trend = 0.0003). The mixed-modern pattern was inversely associated with prevalence of metabolic syndrome (the highest quintile: prevalence ratio = 0.79; 95% CI: 0.69, 0.91; P-trend = 0.006).Conclusion: Mixed dietary patterns containing healthier foods, rather than a largely imported and processed modern diet, may help prevent metabolic syndrome in Samoa.

A thrifty variant in CREBRF strongly influences body mass index in Samoans

Samoans are a unique founder population with a high prevalence of obesity, making them well suited for identifying new genetic contributors to obesity. We conducted a genome-wide association study (GWAS) in 3,072 Samoans, discovered a variant, rs12513649, strongly associated with body mass index (BMI) (P = 5.3 × 10(-14)), and replicated the association in 2,102 additional Samoans (P = 1.2 × 10(-9)). Targeted sequencing identified a strongly associated missense variant, rs373863828 (p.Arg457Gln), in CREBRF (meta P = 1.4 × 10(-20)). Although this variant is extremely rare in other populations, it is common in Samoans (frequency of 0.259), with an effect size much larger than that of any other known common BMI risk variant (1.36-1.45 kg/m(2) per copy of the risk-associated allele). In comparison to wild-type CREBRF, the Arg457Gln variant when overexpressed selectively decreased energy use and increased fat storage in an adipocyte cell model. These data, in combination with evidence of positive selection of the allele encoding p.Arg457Gln, support a 'thrifty' variant hypothesis as a factor in human obesity.

Barriers to adequate prenatal care utilization in American Samoa

The objective of this study is to describe the utilization of prenatal care in American Samoan women and to identify socio-demographic predictors of inadequate prenatal care utilization. Using data from prenatal clinic records, women (n = 692) were categorized according to the adequacy of prenatal care utilization index as having received adequate plus, adequate, intermediate or inadequate prenatal care during their pregnancy. Categorical socio-demographic predictors of the timing of initiation of prenatal care (week of gestation) and the adequacy of received services were identified using one way analysis of variance and independent samples t tests. Between 2001 and 2008 85.4 % of women received inadequate prenatal care. Parity (P = 0.02), maternal unemployment (P = 0.03), and both parents being unemployed (P = 0.03) were negatively associated with the timing of prenatal care initiation. Giving birth in 2007-2008, after a prenatal care incentive scheme had been introduced in the major hospital, was associated with earlier initiation of prenatal care (20.75 vs. 25.12 weeks; P < 0.01) and improved adequacy of received services (95.04 vs. 83.8 %; P = 0.02). The poor prenatal care utilization in American Samoa is a major concern. Improving healthcare accessibility will be key in encouraging women to attend prenatal care. The significant improvements in the adequacy of prenatal care seen in 2007-2008 suggest that the prenatal care incentive program implemented in 2006 may be a very positive step toward addressing issues of prenatal care utilization in this population.

Impact of a diabetes control and management intervention on health care utilization in American Samoa

OBJECTIVES

To examine the impact of a successful 12-month behavioral intervention to improve diabetes control on health care utilization in American Samoa.

METHODS

A cluster-randomized design was used to assign 268 diabetes patients to a nurse-community health worker intervention or usual care. Hospitalizations, emergency department, and primary care physician visits were collected retrospectively for 1 year prior to, and during, the intervention to assess changes in health care utilization. The association of utilization changes with change in HbA1c during the intervention was assessed.

RESULTS

Adjusted incidence rate ratios (RR) for primary care physician visits were significantly higher in the community health worker relative to the usual care group (RR = 1.71; 95% CI, 1.25-2.33). There was no main intervention effect on emergency department utilization, but visits in the prior year modified the intervention effect on emergency department visits. Increased primary care physician utilization was associated with greater decreases in HbA1c (b = -0.10, SE = 0.04, p = 0.01).

CONCLUSIONS

A culturally adapted community health worker diabetes intervention in American Samoa significantly increased primary care physician visits, and decreased emergency department visits among those with high emergency department usage in the prior year. These changes suggest important and beneficial impacts on health system utilization from the diabetes intervention in a low resource and high-risk population.

Prevalence of adiposity and associated cardiometabolic risk factors in the Samoan genome-wide association study

OBJECTIVE

To describe the prevalence of obesity-related noncommunicable diseases (NCDs) and associated risk factors in a sample of Samoan adults studied in 2010 as part of a genome-wide assocation study (GWAS) for obesity related traits.

METHODS

Anthropometric and biochemical data collected from n = 3,475 participants (n = 1,437 male; n = 2,038 female) aged 24.5 to <65 years were used to describe the prevalence of obesity, diabetes, hypertension, and dyslipidemia within the study sample. One way analysis of variance, χ(2) tests, and binary logistic regression were used to identify differences in disease and risk factor prevalence by 10-year age group, gender, or by census region of residence.

RESULTS

Obesity was highly prevalent among the study sample; 64.6% of females and 41.2% of males were obese according to Polynesian cutoffs (BMI ≥ 32 kg/m(2) ). Females were less likely than males to have hypertension (31.7% vs. 36.7%) but equally likely to have diabetes (17.8% vs. 16.4%). With the exception of obesity and low HDL-cholesterol in females only, there were significant differences in the prevalence of all NCDs and associated risk factors by age group, with the oldest age group (55 to <65 years) most affected. In both sexes, residents of the Apia Urban Area were at significantly greater risk of obesity, diabetes, low HDL-cholesterol, and high triglycerides than residents of the more rural Savaii region.

CONCLUSIONS

The phenotypic characteristics of this sample provide evidence of a continuation of previously reported temporal trends toward obesity and its associated disorders. Attention must be paid to the critical NCD situation in Samoa.

Modeling metabolic syndrome through structural equations of metabolic traits, comorbid diseases, and GWAS variants

OBJECTIVE

To provide a quantitative map of relationships between metabolic traits, genome-wide association studies (GWAS) variants, metabolic syndrome (MetS), and metabolic diseases through factor analysis and structural equation modeling (SEM).

DESIGN AND METHODS

Cross-sectional data were collected on 1,300 individuals from an eastern Adriatic Croatian island, including 14 anthropometric and biochemical traits, and diagnoses of type 2 diabetes, coronary heart disease, gout, kidney disease, and stroke. MetS was defined based on Adult Treatment Panel III criteria. Forty widely replicated GWAS variants were genotyped. Correlated quantitative traits were reduced through factor analysis; relationships between factors, genetic variants, MetS, and metabolic diseases were determined through SEM.

RESULTS

MetS was associated with obesity (P < 0.0001), dyslipidemia (P < 0.0001), glycated hemoglobin (HbA1c; P = 0.0013), hypertension (P < 0.0001), and hyperuricemia (P < 0.0001). Of metabolic diseases, MetS was associated with gout (P = 0.024), coronary heart disease was associated with HbA1c (P < 0.0001), and type 2 diabetes was associated with HbA1c (P < 0.0001) and obesity (P = 0.008). Eleven GWAS variants predicted metabolic variables, MetS, and metabolic diseases. Notably, rs7100623 in HHEX/IDE was associated with HbA1c (β = 0.03; P < 0.0001) and type 2 diabetes (β = 0.326; P = 0.0002), underscoring substantial impact on glucose control.

CONCLUSIONS

Although MetS was associated with obesity, dyslipidemia, glucose control, hypertension, and hyperuricemia, limited ability of MetS to indicate metabolic disease risk is suggested.

Implementation of a culturally tailored diabetes intervention with community health workers in American Samoa

PURPOSE

The purpose of this article is to answer key implementation questions from our translation research with a primary care-based, nurse-community health worker (CHW) team intervention to support type 2 diabetes self-management.

METHODS

Descriptive data are given on intervention delivery, CHW visit content, patient safety, and intervention costs, along with statistical analyses to examine participant characteristics of higher attendance at visits.

RESULTS

In the intervention sample (n = 104), 74% (SD = 16%) of planned intervention visits occurred, guided by an algorithm-based protocol. Higher risk participants had a significantly lower dose of their weekly assigned visits (66%) than those at moderate (74%) and lower risk (90%). Twenty-eight percent of participants moved to a lower risk group over the year. Estimated intervention cost was $656 per person. Participants with less education were more likely to attend optimal percentage of visits.

CONCLUSIONS

A nurse-CHW team can deliver a culturally adapted diabetes self-management support intervention with excellent fidelity to the algorithm-based protocols. The team accommodated participants' needs by meeting them whenever and wherever they could. This study provides an example of adaptation of an evidence-based model to the Samoan cultural context and its resource-poor setting.

Trends in overweight among women differ by occupational class: results from 33 low- and middle-income countries in the period 1992-2009

OBJECTIVE

There has been an increase in overweight among women in low- and middle-income countries but whether these trends differ for women in different occupations is unknown. We examined trends by occupational class among women from 33 low- and middle-income countries in four regions.

DESIGN

Cross-national study with repeated cross-sectional demographic health surveys.

SUBJECTS

Height and weight were assessed at least twice between 1992 and 2009 in 248,925 women aged 25-49 years. Interviews were conducted to assess occupational class, age, place of residence, educational level, household wealth index, parity, age at first birth and breastfeeding. We used logistic and linear regression analyses to assess the annual percent change in overweight (body mass index >25 kg m(-2)) by occupational class.

RESULTS

The prevalence of overweight ranged from 2.2% in Nepal in 1992-1997 to 75% in Egypt in 2004-2009. In all the four regions, women working in agriculture had consistently lower prevalence of overweight, while women from professional, technical, managerial as well as clerical occupational classes had higher prevalence. Although the prevalence of overweight increased in all the occupational classes in most regions, women working in agriculture and production experienced the largest increase in overweight over the study period, while women in higher occupational classes experienced smaller increases. To illustrate, overweight increased annually by 0.5% in Latin America and the Caribbean and by 0.7% in Sub-Saharan Africa among women from professional, technical and managerial classes, as compared with 2.8% and 3.7%, respectively, among women in agriculture.

CONCLUSION

The prevalence of overweight has increased in most low- and middle-income countries, but women working in agriculture and production have experienced larger increases than women in higher occupational classes.

INSIG2 variants, dietary patterns and metabolic risk in Samoa

BACKGROUND/OBJECTIVES

Association of insulin-induced gene 2 (INSIG2) variants with obesity has been confirmed in several but not all follow-up studies. Differences in environmental factors across populations may mask some genetic associations and therefore gene-environment interactions should be explored. We hypothesized that the association between dietary patterns and components of the metabolic syndrome could be modified by INSIG2 variants.

SUBJECTS/METHODS

We conducted a longitudinal study of adiposity and cardiovascular disease risk among 427 and 290 adults from Samoa and American Samoa (1990-1995). Principal component analysis on food items from a validated food frequency questionnaire was used to identify neotraditional and modern dietary patterns. We explored gene-dietary pattern interactions with the INSIG2 variants rs9308762 and rs7566605.

RESULTS

Results for American Samoans were mostly nonsignificant. In Samoa, the neotraditional dietary pattern was associated with lower triglycerides, body mass index (BMI), waist circumference, systolic and diastolic blood pressure and fasting glucose (all P-for-trend<0.05). The modern pattern was significantly associated with higher triglycerides, BMI, waist circumference and lower high-density lipoprotein-cholesterol (all P-for-trend<0.05). A significant interaction for triglycerides was found between the modern pattern and the rs9308762 polymorphism (P=0.04). Those from Samoa consuming the modern pattern have higher triglycerides if they are homozygous for the rs9308762 C allele.

CONCLUSIONS

The common INSIG2 variant rs9308762 was associated with poorer metabolic control and a greater sensitivity of trigylcerides to a modern dietary pattern. Environmental factors need to be taken into account when assessing genetic associations across and within populations.

Modernization and cardiometabolic risk in Samoan adolescents

OBJECTIVE

To describe the prevalence of cardiometabolic risk factor clustering in Samoan adolescents and to relate risk factor clustering to weight status and general modernization.

METHODS

Anthropometric and biochemical data collected from adolescents aged 12-17.9 years who participated in the Samoan Family Study of Overweight and Diabetes were used to describe the prevalence of cardiometabolic risk factors (high waist circumference, high blood pressure, high triglyceride level, low-high-density lipoprotein cholesterol, and high fasting serum glucose). A total of 436 adolescents were included in this analysis; 237 (54.4%) from American Samoa (n = 123 males) and 199 (45.6%) from Samoa (n = 90 males). Risk factor clustering was indicated by the presence of ≥ 3 risk factors.

RESULTS

Cardiometabolic risk factor clustering was greater in American Samoan adolescents (17.9% males, 21.9% females) than Samoan adolescents (1.1% males, 2.8% females). The frequency of risk factor clustering varied according to body mass index status. In males, risk factor clustering was entirely confined to obese adolescents, whereas female adolescents who were overweight or obese were at risk.

CONCLUSIONS

Cardiometabolic risk factor clustering is prevalent in the young American Samoan population and is likely to become more prevalent with increasing modernization in Samoan youth. Screening and intervention should be targeted at this age group to reduce the non-communicable disease burden faced by these populations.

Long-term trends in food availability, food prices, and obesity in Samoa

OBJECTIVES

To describe long-term food availability and prices from 1961 to 2007 and body mass index (BMI) trends from 1980 to 2010 in Samoa, and to contextualize these trends within political, economic, cultural, behavioral, and climatic influences.

METHODS

National level data on food availability and pricing were obtained from the open access database FAO (http://faostat.fao.org). Data for Samoa were collected from annual food balance sheets available for the period 1961-2007. Mean BMI for Samoan men and women aged 35-44 years of age is reported from four different time periods, 1979-1982, 1991, 2003, and 2010.

RESULTS

Total energy availability increased substantially, by 47%, with more than 900 extra calories available per capita per day in 2007 than in 1961. Many of these extra calories are supplied by dietary fat, the availability of which rose by a proportionally greater amount, 73%. Availability of both meat and vegetable oils rose substantially. Poultry meat increased the most proportionally, from 10 to 117 kcal per capita per day. Coconut products, fruits, and starchy root crops-all locally grown-showed little to no increase over this time. As import prices for poultry and mutton increased their availability decreased, but the availability of vegetable oils rose despite a rise in their price. Mean BMI for men and women aged 35-44 years rose 18% rise from 1980 to 2010.

CONCLUSIONS

These long-term trends in food availability and prices, and the temporal pattern of BMI provide national level data for understanding the process of the nutritional transition in Samoa. Further work on consumer food prices, diet, food security, and health is needed to further contextualize the transformation of the local food system in Samoa.

Prevalence of metabolic syndrome and related metabolic traits in an island population of the Adriatic

BACKGROUND

Metabolic syndrome, a constellation of risk factors associated with cardiovascular disease and Type 2 diabetes, has reached epidemic proportions worldwide. Epidemiological studies in transitional societies will provide insight into the underlying factors that interact in its manifestation.

AIMS

To estimate the prevalence of metabolic syndrome, provide a comparative analysis of two metabolic syndrome definitions and assess clustering and association of metabolic traits and cardiovascular diseases in an Adriatic island population.

SUBJECTS AND METHODS

In a cross-sectional study, data on four anthropometric, blood pressure and 11 biochemical traits were obtained from 1430 adults from the island of Hvar.

RESULTS

Prevalence of metabolic syndrome was 25% and 38.5% based on Adult Treatment Panel III and International Diabetes Federation definitions, respectively. Rates of abdominal obesity, elevated blood glucose and hypertension were high. Among the traits not included in the definitions, levels of LDL, total cholesterol and fibrinogen were markedly elevated. The majority of the phenotypes were significantly associated with the syndrome, the strongest being waist circumference.

CONCLUSION

The Croatian islanders are characterized by a high prevalence of metabolic abnormalities. Central obesity is the strongest contributor of the syndrome. With a high prevalence of dyslipidemia and pro-inflammatory factors, the population is at substantial risk for cardiovascular diseases.

Evidence for a continuing gap in rural/urban adult obesity in the Samoan archipelago

Significant differences in adult obesity prevalence exist between rural and urban settings throughout the world. Here, we estimate and evaluate the prevalence of adult obesity in rural Independent Samoa, rural American Samoa, and urban American Samoa in 2009. Volunteers over the age of 40 years were weighed and measured by convenience sampling in rural Independent Samoa (N = 85), rural American Samoa (N = 124), and urban American Samoa (N = 95) Mean BMI increased from rural Independent Samoa (32.2 males; 33.3 females) to rural American Samoa (33.5 males; 34.9 females) to urban American Samoa (36.9 males; 39.7 females). Differences among groups were statistically significant (P = 0.004, ANOVA). In all locations, women were substantially more obese than men. While obesity is a major health problem in the Samoan archipelago, significant differences exist between rural and urban settings. A substantial rural/urban gap in adult obesity has been in existence since at least the 1970s. However, results of our study, combined with those of previous studies, indicate that the prevalence of obesity in both rural and urban environments has been on the rise since the 1970s.

Common variants in FTO are not significantly associated with obesity-related phenotypes among Samoans of Polynesia

The association between obesity and the fat mass and obesity-associated (FTO) gene has been widely replicated among Caucasian populations. The limited number of studies assessing its significance in Asian populations has been somewhat conflicting. We performed a genetic association study of 51 tagging, genome-wide association studies, and imputed single nucleotide polymorphisms with 12 measures of adiposity and skeletal robustness in two Samoan populations of Polynesia. We included 465 and 624 unrelated American Samoan and Samoan individuals, respectively; these populations derive from a single genetic background traced to Southeast Asia and represent one sociocultural unit, although they are economically disparate with distinct environmental exposures. American Samoans were significantly larger than Samoans in all measures of obesity and most measures of skeletal robustness. In separate analyses of American Samoa and Samoa, we found a total of 36 nominal associations between FTO variants and skeletal and obesity measures. The preponderance of these nominal associations (32 of 36) was observed in the Samoan population, and predominantly with skeletal rather than fat mass measures (28 of 36). All significance disappeared, however, following corrections for multiple testing. Based on these findings, it could be surmised that FTO is not likely a major obesity locus in Polynesian populations.

Behavioral and perceived stressor effects on urinary catecholamine excretion in adult Samoans

OBJECTIVES

The effects of perceptions and behaviors related to culturally patterned socioeconomic obligations on catecholamine excretion rates were studied in a cross-sectional sample of Samoan adults.

METHODS

A total of 378 participants, ages 29-62 years, from 9 villages throughout Samoa, provided timed overnight urine specimens, and self-reported perceptions and behaviors associated with contributions to one's family, aiga, and chief, matai, and communal gift exchanges, fa'alavelave. Urinary norepinephrine and epinephrine excretion rates were measured by high performance liquid chromatography with electrochemical detection. Age (≤40 vs. >40 years) and gender-specific regression models were estimated to detect associations with catecholamine excretion.

RESULTS

Young women who contribute more to their matai, who consider fa'alavelave to be a financial strain, and who view their contribution to their matai to be "just right," had significantly higher residence-adjusted norepinephrine excretion. Young women who contribute more to their matai, who consider fa'alavelave to be a financial strain, and who consider their contribution to their aiga not to be a burden, had higher epinephrine excretion. Older men who contribute more to their aiga and who perceive their contribution to their aiga to be "just right" had increased residence-adjusted epinephrine excretion.

CONCLUSIONS

Individual-level perceptions and behaviors related to traditional socioeconomic obligations are a significant correlate of increased overnight catecholamine excretion rates. Higher excretion rates may be attributed to psychosocial stress arousal associated with a discordance between personal desires for upward social mobility, and family and community-based socioeconomic obligations. Changes in patterns of individual-level psychosocial stress arousal may contribute to cardiovascular disease risk in modernizing Samoans.

First assessment of menstrual cycle function and reproductive endocrine status in Samoan women

BACKGROUND

American Samoa and Samoa are now characterized by one of the world's highest levels of adult overweight and obesity. Our objective was to investigate patterns of menstrual cyclicity reported by Samoan women and examine the relationship to adiposity and select hormone levels.

METHODS

A cross-sectional analysis was performed among Samoan women, aged 18-39 years (n = 322), using anthropometric and biomarker measures of adiposity and reproductive health, including insulin, adiponectin, testosterone, sex hormone-binding globulin, free androgen index (FAI) and mullerian-inhibiting substance (MIS). Menstrual regularity was assessed from self-reported responses. Multivariable models were estimated to adjust for potential confounding of the associations between menstrual patterns and other measures.

RESULTS

A high proportion of the women (13.7%) reported oligomenorrhea or amenorrhea (OM/AM). More than three-quarters, 80.7%, of women were either overweight or obese, using Polynesian-specific criteria, and OM/AM was significantly associated with higher BMI. Abdominal circumference and insulin levels were significantly higher, and adiponectin levels were lower, in those who reported OM/AM versus regular menstruation. The FAI was higher in women with increased BMI. MIS levels declined with age, more slowly in those reporting OM/AM.

CONCLUSIONS

Self-reported OM/AM was associated with an elevated BMI, abdominal adiposity and serum insulin, and with reduced adiponectin levels. These findings support a high rate of metabolic syndrome, and perhaps PCOS and reproductive dysfunction, among Samoan women.

Cultural translation of interventions: diabetes care in American Samoa

Translation of research advances into clinical practice for at-risk communities is important to eliminate disease disparities. Adult type 2 diabetes prevalence in the US territory of American Samoa is 21.5%, but little intervention research has been carried out there. We discuss our experience with cultural translation, drawing on an emerging implementation science, which aims to build a knowledge base on adapting interventions to real-world settings. We offer examples from our behavioral intervention study, Diabetes Care in American Samoa, which was adapted from Project Sugar 2, a nurse and community health worker intervention to support diabetes self-management among urban African Americans. The challenges we experienced and solutions we used may inform adaptations of interventions in other settings.

A tagging SNP in INSIG2 is associated with obesity-related phenotypes among Samoans

Background

A genome wide association study found significant association of a sequence variant, rs7566605, in the insulin-induced gene 2 (INSIG2) with obesity. However, the association remained inconclusive in follow-up studies. We tested for association of four tagging SNPs (tagSNPs) including this variant with body mass index (BMI) and abdominal circumference (ABDCIR) in the Samoans of the Western Pacific, a population with high levels of obesity.

Methods

We studied 907 adult Samoan participants from a longitudinal study of adiposity and cardiovascular disease risk in two polities, American Samoa and Samoa. Four tagSNPs were identified from the Chinese HapMap database based on pairwise r² of ≥0.8 and minor allele frequency of ≥0.05. Genotyping was performed using the TaqMan assay. Tests of association with BMI and ABDCIR were performed under the additive model.

Results

We did not find association of rs7566605 with either BMI or ABDCIR in any group of the Samoans. However, the most distally located tagSNPs in Intron 3 of the gene, rs9308762, showed significant association with both BMI (p-value 0.024) and ABDCIR (p-value 0.009) in the combined sample and with BMI (p-value 0.038) in the sample from Samoa.

Conclusion

Although rs7566605 was not significantly associated with obesity in our study population, we can not rule out the involvement of INSIG2 in obesity related traits as we found significant association of another tagSNP in INSIG2 with both BMI and ABDCIR. This study suggests the importance of comprehensive assessment of sequence variants within a gene in association studies.

Interdisciplinary Translational Research in Anthropology, Nutrition, and Public Health

This review focuses on several human population health research topics that exemplify interdisciplinary concepts and approaches from anthropology, nutrition, and public health with an emphasis on applied or translational global health implications. First, a recent study on neonatal survival in a resource-poor region emphasizes how health can be markedly improved with detailed translation and implementation of evidence from all three disciplines. Second, schistosomiasis, a parasitic worm infection, is reviewed with an emphasis on developing a consensus of its nutritional health burdens and the next translational research steps needed to improve control of both infection transmission and disease. Last, the author's long-term Samoan nutrition and health studies are described with a focus on new translational research to improve diabetes. This selective review attempts to provide a rationale for the intersections of anthropology, nutrition, and public health to proceed with fundamental biological, cultural, and behavioral research to reduce health inequalities globally and domestically.

Dietary patterns are associated with metabolic syndrome in adult Samoans

The prevalence of metabolic syndrome has reached epidemic levels in the Samoan Islands. In this cross-sectional study conducted in 2002-2003, dietary patterns were described among American Samoan (n = 723) and Samoan (n = 785) adults (> or =18 y) to identify neo-traditional and modern eating patterns and to relate these patterns to the presence of metabolic syndrome using Adult Treatment Panel III criteria. The neo-traditional dietary pattern, similar across both polities, was characterized by high intake of local foods, including crab/lobster, coconut products, and taro, and low intake of processed foods, including potato chips and soda. The modern pattern, also similar across both polities, was characterized by high intake of processed foods such as rice, potato chips, cake, and pancakes and low intake of local foods. The neo-traditional dietary pattern was associated with significantly higher serum HDL-cholesterol in American Samoa (P-trend = 0.05) and a decrease in abdominal circumference in American Samoa and Samoa (P-trend = 0.004 and 0.01, respectively). An inverse association was found with metabolic syndrome, although it did not reach significance (P = 0.23 in American Samoa; P = 0.13 in Samoa). The modern pattern was significantly positively associated with metabolic syndrome in Samoa (prevalence ratio = 1.21 for the fifth compared with first quintile; 95% CI: 0.93.1.57; P-trend = 0.05) and with increased serum triglyceride levels in both polities (P < 0.05). Reduced intake of processed foods high in refined grains and adherence to a neo-traditional eating pattern characterized by plant-based fiber, seafood, and coconut products may help to prevent growth in the prevalence of metabolic syndrome in the Samoan islands.

Adiponectin and type 2 diabetes in Samoan adults

OBJECTIVE

Previous studies have established an association between adiponectin and type 2 diabetes. It is unclear whether adiponectin will be useful among Samoan Islanders, characterized by markedly elevated levels of obesity, in differentiating those at risk of developing type 2 diabetes.

METHODS

Cross-sectional, genetic epidemiology study of obesity in American Samoa and Samoa 2002-2003 (n = 1,599). Logistic regression provided adjusted odds ratios and 95% confidence intervals for the association between adiponectin, diabetes, and prediabetes (impaired fasting glucose).

RESULTS

There is a significant decreasing trend in the odds of diabetes and prediabetes across increasing quintiles of adiponectin with an OR of 2.8 (95% CI: 1.6, 5.0) and 2.9 (95% CI: 1.5, 5.7), respectively, in the lowest relative to the highest quintile of adiponectin (P-for-trend = 0.004 and 0.001).

CONCLUSIONS

Adiponectin is an important correlate, independent of other risk factors, of the pathogenesis of type 2 diabetes among Samoan islanders and may help distinguish those at higher risk of developing this disease.

Susceptibility loci for adiposity phenotypes on 8p, 9p, and 16q in American Samoa and Samoa

Obesity is a complex phenotype affected by genetic and environmental influences such as sociocultural factors and individual behaviors. Previously, we performed two separate genome-wide investigations for adiposity-related traits (BMI, percentage body fat (%BF), abdominal circumference (ABDCIR), and serum leptin and serum adiponectin levels) in families from American Samoa and in families from Samoa. The two polities have a common evolutionary history but have lately been influenced by variations in economic development, leading to differences in income and wealth and in dietary and physical activity patterns. We now present a genome-wide linkage scan of the combined samples from the two polities. We adjust for environmental covariates, including polity of residence, education, cigarette smoking, and farm work, and use variance component methods to calculate univariate and bivariate multipoint lod scores. We identified a region on 9p22 with genome-wide significant linkage for the bivariate phenotypes ABDCIR-%BF (1-d.f. lod 3.30) and BMI-%BF (1-d.f. lod 3.31) and two regions with genome-wide suggestive linkage on 8p12 and 16q23 for adiponectin (lod 2.74) and the bivariate phenotype leptin-ABDCIR (1-d.f. lod 3.17), respectively. These three regions have previously been reported to be linked to adiposity-related phenotypes in independent studies. However, the differences in results between this study and our previous polity-specific studies suggest that environmental effects are of different importance in the samples. These results strongly encourage further genetic studies of adiposity-related phenotypes where extended sets of carefully measured environmental factors are taken into account.

A whole genome linkage scan identifies multiple chromosomal regions influencing adiposity-related traits among Samoans

We conducted a genome-wide scan in 46 pedigrees, with 671 phenotyped adults, from the independent nation of Samoa to map quantitative trait loci (QTLs) for adiposity-related phenotypes, including body mass index (BMI), abdominal circumference (ABDCIR), percent body fat (%BFAT), and fasting serum leptin and adiponectin. A set of 378 autosomal and 14 X chromosomal microsatellite markers were genotyped in 572 of the adults. Significant genetic correlations (0.82-0.96) were detected between pairs of BMI, ABDCIR, %BFAT and leptin. Suggestive linkages were found on 13q31 (LOD = 2.30 for leptin, LOD = 2.48 for %BFAT, LOD = 2.04 for ABDCIR, and LOD = 2.09 for BMI) and on 9p22 (LOD = 3.08 for ABDCIR and LOD = 2.53 for %BFAT). Furthermore, bivariate linkage analyses indicated that the genetic regions on 9p22 (bivariate LOD 2.35-3.10, LOD(eq) (1df) 1.88-2.59) and 13q31 (bivariate LOD 1.96-2.64, LOD(eq) 1.52-2.21) might harbor common major genes with pleiotropic effects. Other regions showing suggestive linkage included 4q22 (LOD = 2.95) and 7p14 (LOD = 2.64) for %BFAT, 2q13 for adiponectin (LOD = 2.05) and 19q12 for BMI-adjusted leptin (LOD = 2.03). Further fine mapping of these regions may help identify the genetic variants contributing to the development of obesity in Samoan adults.

A genome-wide linkage scan identifies multiple chromosomal regions influencing serum lipid levels in the population on the Samoan islands

Abnormal lipid levels are important risk factors for cardiovascular diseases. We conducted genome-wide variance component linkage analyses to search for loci influencing total cholesterol (TC), LDL, HDL and triglyceride in families residing in American Samoa and Samoa as well as in a combined sample from the two polities. We adjusted the traits for a number of environmental covariates, such as smoking, alcohol consumption, physical activity, and material lifestyle. We found suggestive univariate linkage with log of the odds (LOD) scores > 3 for LDL on 6p21-p12 (LOD 3.13) in Samoa and on 12q21-q23 (LOD 3.07) in American Samoa. Furthermore, in American Samoa on 12q21, we detected genome-wide linkage (LOD(eq) 3.38) to the bivariate trait TC-LDL. Telomeric of this region, on 12q24, we found suggestive bivariate linkage to TC-HDL (LOD(eq) 3.22) in the combined study sample. In addition, we detected suggestive univariate linkage (LOD 1.9-2.93) on chromosomes 4p-q, 6p, 7q, 9q, 11q, 12q 13q, 15q, 16p, 18q, 19p, 19q and Xq23 and suggestive bivariate linkage (LOD(eq) 2.05-2.62) on chromosomes 6p, 7q, 12p, 12q, and 19p-q. In conclusion, chromosome 6p and 12q may host promising susceptibility loci influencing lipid levels; however, the low degree of overlap between the three study samples strongly encourages further studies of the lipid-related traits.

Genome-wide scan for adiposity-related phenotypes in adults from American Samoa

OBJECTIVE

To detect quantitative trait loci influencing adiposity-related phenotypes assessed by body mass index (BMI), abdominal circumference (ABDCIR), percent body fat (%BFAT) and fasting serum leptin and adiponectin using a whole genome linkage scan of families from American Samoa.

DESIGN

Family-based linkage analysis, the probands and family members were unselected for obesity.

SUBJECTS

A total of 583 phenotyped American Samoan adults, of which 578 were genotyped in 34 pedigrees.

MEASUREMENTS

A total of 377 autosomal and 18 X chromosome microsatellite markers were typed at an approximate average spacing of 10 cM spanning the genome. Multipoint LOD (logarithm of the odds) scores were calculated using variance-components approaches and SOLAR/LOKI software. The covariates simultaneously evaluated were age, sex, education, farm work and cigarette smoking, with a significance level of 0.1. Due to the stochastic nature of LOKI, we report the average of maximum LOD scores from 10 runs.

RESULTS

Significant linkage to leptin was found at 6q32.2 with LOD of 3.83. Suggestive linkage to leptin was found at 16q21:LOD=2.98, 1q42.2:LOD=1.97, 5q11.2:LOD=2.08, 12q24.23:LOD=2.00, 19p13.3:LOD=2.05; adiponectin was linked to 13q33.1-q22.1:LOD=2.41; %BFAT was linked to 16q12.2-q21, LOD=2.24; ABDCIR was linked to 16q23.1:LOD=1.95; %BFAT-adjusted leptin to 14q12, LOD=2.01; %BFAT-adjusted ABDCIR to 1q31.1, LOD=2.36, to 3q27.3-q28, LOD=2.10 and to 12p12.3, LOD=2.04.

CONCLUSION

We found strong evidence for a major locus on 6q23.2 influencing serum leptin levels in American Samoans. The 16q21 region appears to harbor a susceptibility locus that has significant pleiotrophic effects on phenotypes BMI, %BFAT, leptin and ABDCIR as shown by bivariate linkage analyses. Several other loci of varying significance were detected across the genome.

The influence of socioeconomic factors on cardiovascular disease risk factors in the context of economic development in the Samoan archipelago

Early in economic development there are positive associations between socioeconomic status (SES) and cardiovascular disease (CVD) risk factors, and in the most developed market economy societies there are negative associations. The purpose of this report is to describe cross-sectional and longitudinal associations between indicators of SES and CVD risk factors in a genetically homogenous population of Samoans at different levels of economic development. At baseline 1289 participants 25-58yrs, and at 4-year follow-up, 963 participants were studied in less economically developed Samoa and in more developed American Samoa. SES was assessed by education, occupation, and material lifestyle at baseline. The CVD risk factors, obesity, type-2 diabetes and hypertension were measured at baseline and 4-year follow-up, and an index of any incident CVD risk factor at follow-up was calculated. Sex and location (Samoa and American Samoa) specific multivariable logistic regression models were used to test for relationships between SES and CVD risk factors at baseline after adjustment for age and the other SES indicators. In addition an ordinal SES index was constructed for each individual based on all three SES indicators, and used in a multivariable model to estimate the predicted probability of CVD risk factors across the SES index for the two locations. In both the models using specific SES measures and CVD risk factor outcomes, and the models using the ordinal SES index and predicted probabilities of CVD risk factors, we detected a pattern of high SES associated with: (1) elevated odds of CVD risk factors in less developed Samoa, and (2) decreased odds of CVD risk factors in more developed American Samoa. We conclude that the pattern of inverse associations between SES and CVD risk factors in Samoa and direct associations in American Samoa is attributable to the heterogeneity across the Samoas in specific exposures to social processes of economic development and the natural history of individual CVD risk factors. The findings suggest that interventions on non-communicable diseases in the Samoas must be devised based on the level of economic development, the socio-economic context of risk factor exposures, and individual characteristics such as age, sex and education level.