Prevalence of adiposity and associated cardiometabolic risk factors in the samoan genome‐wide association study

Abstract

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, χ2 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/m2). 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.

Cut-off levels for hyperandrogenemia among Samoan women: An improved methodology for deriving normative data in an obese population

“…Given the rise in average BMI and prevalence of obesity globally, other studies can use a similar approach in defining biochemical HA among their study samples because values must be population-specific, as androgen values vary across ethnicities [6]. As such, we caution our findings may not be generalizable to other populations, as these results may be associated with Samoan genetic and life course influences on adiposity during the nutrition transition [1]. …”

“…The GWAS recruited adults aged 24.5 to < 65 years of Samoan descent (four Samoan grandparents) from thirty-three villages in independent Samoa [1]. …”

“…The standard procedures for anthropometric measurements have been described by Hawley et al [1]. Categorical definitions of BMI based upon body composition measures among Polynesians were used to define overweight (BMI 26–32 kg/m 2 ) and obesity (BMI > 32 kg/m 2 ), cutoffs equivalent to the standard World Health Organization (WHO) cutoffs of 25 and 30 kg/m 2 , respectively, after taking into account the greater lean mass of Polynesians [15].…”

“…In a 2010 survey, 91.3% of women and 80.4% of men were overweight or obese, based on Polynesian body composition derived criteria for body mass index (BMI; BMI ≥ 26 kg/m 2 ) [1]. Despite the increasing burden of obesity among women in developing countries, its impact on reproductive health is not well-understood.…”

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

“… Samoans are a unique founder population with a high prevalence of obesity 1–3 , making them well suited for identifying new genetic contributors to obesity 4 . 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 ).…”