Association of body-shape phenotypes with imaging measures of body composition in the UK Biobank cohort: relevance to colon cancer risk

Abstract

Background Body mass index (BMI), waist and hip circumference are strongly correlated and do not reflect body composition. A Body Shape Index (ABSI) and Hip Index (HI) define waist and hip size among individuals with the same weight and height and would thus reflect body density. We examined differences in body composition between body-shape phenotypes defined with ABSI and HI and used this information to propose explanations for associations between body-shape phenotypes and colon cancer risk. Methods We used data from the UK Biobank Resource for 15,520 men, 16,548 women with dual-emission X-ray absorptiometry (DXA) measurements; 3997 men, 4402 women with magnetic resonance imaging (MRI) measurements; 200,289 men, 230,326 women followed-up for colon cancer. We defined body-shape phenotypes as: large-ABSI-small-HI (“apple”), small-ABSI-large-HI (“pear”), small-ABSI-small-HI (“slim”), large-ABSI-large-HI (“wide”). We evaluated differences in body composition in linear models and associations with colon cancer risk in Cox proportional hazards models adjusted for confounders and explored heterogeneity by BMI. Results Among individuals with the same height and weight, visceral adipose tissue (VAT) was lowest for “pear” and highest for “apple”, while abdominal subcutaneous adipose tissue (ASAT) was lowest for “slim” and highest for “wide” phenotype. In the gynoid region, differences between “apple” and “pear” phenotypes were accounted for mainly by fat mass in women but by lean mass in men. In men, lean mass was inversely associated with waist size, while the pattern of gynoid fat resembled ASAT in women. Lean and fat mass were higher for higher BMI, but not hand grip strength. Compared to normal weight “pear”, the risk of colon cancer in men (1029 cases) was higher for “apple” phenotype for normal weight (hazard ratio HR = 1.77; 95% confidence interval: 1.16–2.69) and comparably for overweight and obese, higher for “wide” phenotype for overweight (HR = 1.60; 1.14–2.24) and comparably for obese, but higher for “slim” phenotype only for obese (HR = 1.98; 1.35–2.88). Associations with colon cancer risk in women (889 cases) were weaker. Conclusions ABSI-by-HI body-shape phenotypes provide information for body composition. Colon cancer risk in men appears related to ASAT quantity for “slim” and “wide” but to factors determining VAT accumulation for “apple” phenotype.

Associations of body shape phenotypes with sex steroids and their binding proteins in the UK Biobank cohort

“…The UK Biobank cohort includes half a million participants recruited between 2006 and 2010 from the general population of the United Kingdom (UK), at age 40–70 years 13 . Similar to our previous studies 3 , 11 , we have included in the current study only participants with self-reported white ancestry, because the number of participants with other ethnicities was relatively small. In total, we excluded 115,113 participants with missing measurements for testosterone and oestradiol, extreme or missing anthropometric measurements, mismatched genetic and self-reported sex, prevalent cancer at enrolment (defined as previously described 3 ), incident cancer or death within the first two years after enrolment (to minimise the influence of cancer cachexia), women pregnant at enrolment, participants receiving glucocorticoids or drugs influencing the production or action of sex steroids (listed in Supplementary Table S1 ), men receiving testosterone or 5α-reductase inhibitors and women with missing information for use of oral contraceptives or HRT.…”

“…We calculated ABSI for both sexes with coefficients from NHANES 1999–2004 9 , but using waist circumference in mm and not in m as in the original formula, to derive ABSI values in the order of magnitude of waist circumference. We calculated HI for women with coefficients from NHANES III 10 , but HI for men with simple-fraction coefficients based on UK Biobank data 11 , to correct the underlying inverse correlation between HI calculated with the original coefficients and BMI observed in UK Biobank men 3 . …”

“…To define categories of BMI, we used World Health Organisation cut-offs: normal weight (BMI ≥ 18.5 to < 25 kg/m 2 ), overweight (BMI ≥ 25 to < 30 kg/m 2 ), and obese (BMI ≥ 30 to < 45 kg/m 2 ). To define categories of body shape, we used numerical cut-offs for ABSI (≥ 80 for men, ≥ 73 for women) and HI (≥ 49 for men, ≥ 64 for women), which in our previous study on body composition were close to the sex-specific UK Biobank medians 11 . This dichotomisation of ABSI and HI on an absolute scale, similarly to the definition of WHO categories of BMI, permits comparisons between different populations, while a z-score-based classification would be dependent on the mean and SD of each population.…”

“…To overcome this limitation, waist and hip circumference have been scaled to weight and height in the allometric indices “a body shape index” (ABSI) and hip index (HI), which compare waist and hip circumference, correspondingly, for a given individual with the expected average for individuals with the same weight and height 9 , 10 . Using data from UK Biobank, we have previously described the associations of body shape phenotypes based on ABSI and HI with allometric body-composition indices, which similarly to ABSI and HI normalise body composition measurements for weight and height 11 . An analogous approach, normalising body composition measurements for height, BMI, and waist circumference has been used for the 1999–2006 United States National Health and Nutrition Examination Survey (NHANES) 12 .…”

Digital Anthropometry for Body Circumference Measurements: European Phenotypic Variations throughout the Decades

“…Similar to the body mass index, which compares the body mass among individuals with the same height, ABSI and HI compare the waist and hip circumference, respectively, among individuals with the same body height and weight. Cardiometabolic risk factors and various cancers (including several cancers that are not obesity-related) have been positively associated with ABSI and negatively associated with HI [ 24 , 26 , 27 ]. Christakoudi et al [ 28 ] have also recently proposed to combine ABSI and HI to define four different body-shape phenotypes: (i) small-ABSI-small-HI individuals (“slim”); (ii) large-ABSI-large-HI individuals (“large”); (iii) large-ABSI-small-HI individuals (“apple”); (iv) small-ABSI-large-HI individuals (“pear”).…”