Ethnic differences in CT derived abdominal body composition measures: a comparative retrospect pilot study between European and Inuit study population

Figures & data

Figure 1. Show the CT derived body composition at third lumbar level. (a) A 24 year-old man of inuit decent with BMI 23.9; (b) A 19 year-old man of European decent with BMI 23.6; (c) A 29 year-old women of inuit decent with BMI 23.4; (d) A 40 year-old women of European decent with BMI 22.5. BMI: body mass index.

Figure 2. The selected variables are based on the following the simplified directed acyclic graph (DAG).

Figure 3. Shows the flow diagram of exclusion and inclusion of individuals from Nuuk, Greenland. CT: computed tomography.

Table 1. Shows the demographic characteristic for the total study population and stratified by Inuit and European study population.

	Total study population	Inuit	p value*	European	p value*	p value**
Study population, n Men, n Age (years), median (range) Height (m), mean (CI) Men Women Smoking status, n Current Previous Never Not reported Comorbidities type, n Hypertension Hypercholesterolemia	50 30 26 3 14 8 4 4	29 19 33.0 (19.6; 68.5) 1.77 (CI 1.74; 1.80) 1.60 (CI 1.54; 1.65) 16 1 7 6 3 1	0.6796 < 0.0001	21 11 29.7 (18.1; 60.7) 1.78 (CI 1.74; 1.85) 1.64 (CI 1.60; 1.68) 10 2 7 2 1 3	0.3600 < 0.0001	0.5039 0.7838 0.4709 0.1481

CI confidence interval, n number, *Between sexes stratified by ethnicity, **Stratified by ethnicity.

Table 2. Shows the body composition measures (median, (min, max)) between Inuit and European study population.

	Female			Male			p
Body composition measure	Inuit	European	p*	Inuit	European	p*	Between sexes**
SMI, cm^2/m^2 SMD, HU	49.7 (42.9; 56.6) 42.5 (36.5; 48.5)	45.4 (42.3; 48.5) 59.8 (53.9; 65.7)	0.4497 0.0009	64.9 (60.8; 68.9) 49.1 (46.0; 52.1)	60.2 (54.9; 65.5) 49.7 (45.5; 54.0)	0.1966 0.9657	<0.0001 0.5198
SFI, cm^2/m^2 SFD, HU	117.8 (53.0; 203.0)^1 −101.8 (−107.3; −97.8)^1	62.9 (13.8; 98.7) −91.2 (−104.1; −71.5)	0.0164 0.0164	51.6 (10.5; 152.1)^2 −93.4 (−100.9; −67.3)^2	56.0 (17.3; 151.6)^3 −94.7 (−101.9; −77.6) ^3	0.3991 0.5982	0.0947^4 0.03364
VFI, cm^2/m^2 VFD, HU	25.1 (5.7; 99.6) −79.0 (−95.4; −60.8)	12.4 (0.9; 17.7) −66.0 (−77.4; −45.1)	0.0256 0.0494	29.4 (2.8; 88.5) −82.6 (−98.2; −53.8)	33 (13.8; 84.5) −79.9 (−90.9; −64.0)	0.5906 0.4014	0.0166 0.0499
VFA/SFA ratio	0.3 (0.1; 0.5)^1	0.2 (0.05; 0.2)	0.0076	0.5 (0.2; 1.4)^2	0.45 (0.2; 1.2)^3	0.8525	< 0.0001^4
IMFA, cm^2 IMFD, HU	6.6 (2.8; 11.6) −58.3 (−69.3; −52.3)	1.4 (0.3; 13.9) −50.7 (−67.1; −41.6)	0.0126 0.0101	5.6 (1.6; 17.0) −58.5 (−70.4; −51.2)	4.2 (0.8; 25.2) −52.2 (−67.9; −44.7)	0.4514 0.0011	0.2939 0.3326

*Pooled study population same sex; **Pooled study population; ¹two have missing data; ²three have missing data; ³one have missing data; ⁴six have missing data.

HU: Hounsfield Unit, IMFA: Inter and intramuscular fat area, IMFD: Inter and intramuscular fat density, SMA: Skeletal muscle area, SMD: Skeletal muscle density, SMI: Skeletal muscle index, SFA: Subcutaneous fat area, SFD: Subcutaneous fat density, SFI: Subcutaneous fat index, VFA: Visceral fat area, VFD: visceral fat density, VFI: Visceral fat index.

Figure 4. Shows the boxplots of the of body composition measures divided by sex and ethnicity. *p – value < 0.05 between ethnicity stratified by sex **p – value < 0.05 between sexes.

Table 3. Shows the univariate linear regression models for each of the body composition measures and each of the demographic variables ethnicity, age, height, and sex. Results are presented as estimates and 95% confidence intervals.

	Ethnicity Europeans versus Inuit	Age	Sex Women versus men
SMI, cm^2/m^2	6.6 (0.4; 12.8, p = 0.038)	0.1 (- 0.2; 0.3, p = 0.527)	15.6 (11.0; 20.3, p <0.0001)
SMD, HU	− 7.5 (- 12.2; − 2.1, p = 0.003)	− 0.3 (- 0.5; − 0.2, p <0.0001)	− 1.5 (- 6.8; 3.7, p = 0.557)
SFI, cm^2/m^2	16.5 (−12.3; 45.4, p = 0.254)	0.7 (- 0.5; 1.9, p = 0.250)	− 27.3 (- 55.8; 1.1; p = 0.059)
SFD, HU	− 1.9 (- 7.7; 3.9, p = 0.508)	0.1 (- 0.2; 0.3, p = 0.638)	4.2 (- 1.5; 9.9, p = 0.146)
VFI, cm^2/m^2	9.3 (- 5.3; 24.0¸ p = 0.206)	0.7 (0.1; 1.2, p = 0.013)	14.6 (0.2; 29.0, p = 0.048)
VFD, HU	− 8.0 (- 15.4; − 0.6, p = 0.034)	− 0.1 (- 0.4; 0.2, p = 0.438)	−7.8 (- 15.3; − 0.4, p = 0.040)
VFA/SFA ratio	0.1 (- 0.1; 0.3, p = 0.269)	0.01 (0.002; 0.02, p = 0.013)	0.4 (0.2; 0.5, p <0.0001)
IMFA, cm^2	2.0 (- 1.0; 4.9, p = 0.194)	0.1 (0.0002; 0.2, p = 0.050)	1.4 (- 1.6; 4.4, p = 0.359)
IMFD, HU	− 8.2 (- 11.8; − 4.7, p <0.0001)	− 0.06 (- 0.2; 0.1, p = 0.478)	− 2.0 (- 6.3; 2.2, p = 0.342

*six have missing data.

HU: Hounsfield Unit, IMFA: Inter and intramuscular fat area, IMFD: Inter and intramuscular fat density, SMA: Skeletal muscle area, SMD: Skeletal muscle density, SMI: Skeletal muscle index, SFA: Subcutaneous fat area, SFD: Subcutaneous fat density, SFI: Subcutaneous fat index, VFA: Visceral fat area, VFD: visceral fat density, VFI: Visceral fat index.

Table 4. Shows the multiple linear regression predictions for each of the body composition measures based on the variables ethnicity, age, height, and sex.

Multiple linear regression	Adjusted model	p
SMI, cm^2/m^2 Ethnicity European vs Inuit Age (per year) Sex women vs men	4.5 (CI −0.1; 9.1, p = 0.056) 0.05 (CI −0.1; 0.2, p = 0.555) 15.0 (CI 10.4; 19.6, p < 0.0001	<0.0001
SMD, HU Ethnicity European vs Inuit Age (per year) Height (per cm) Sex women vs men	−7.2 (CI −11.6; −2.8, p  = 0.002) −0.3 (CI −0.5; −0.2, p <0.0001) −19.1 (CI −52.9; 14.6, p = 0.260) 2.7 (CI −4.3; 9.7; p = 0.450)	0.0002
SFI, cm^2/m^2 Ethnicity European vs Inuit Age (per year) Sex women vs men	21.1 (−6.7; 48.9, p = 0.133) 0.7 (CI −0.4; 1.9, p = 0.187) −32.4 (CI −60.7; −4.2, p = 0.0.025)	0.0551
SFD, HU Ethnicity European vs Inuit Age (per year) Height (per cm) Sex women vs men	−3.2 (CI −9.2; 2.8, p = 0.285) 0.02 (CI −0.2; 0.3, p = 0.880) −18.0 (CI −63.6; 27.6, p = 0.429) 7.6 (CI −2.1; 17.3, p = 0.121)	0.4484
VFI, cm^2/m^2 Ethnicity European vs Inuit Age (per year) Sex women vs men	6.1 (CI −7.6; 19.8, p = 0.376) 0.7 (CI 0.1; 1.2, p  = 0.015) 16.4 (CI −6.3; 39.1, p = 0.152)	0.0120
VFD, HU Ethnicity European vs Inuit Age (per year) Height (per cm) Sex women vs men	−7.4 (CI −15.0; 0.1, p = 0.053) −0.1 (CI −0.4; 0.2, p = 0.415) −20.0 (CI −78.3; 38.4, p = 0.494) −3.6 (CI −15.7; 8.5, p = 0.554)	0.0722
VFA/SFA ratio Ethnicity European vs Inuit Age (per year) Height (per cm) Sex women vs men	0.04 (CI −0.12; 0.21, p = 0.592) 0.01 (CI −1.22; 1.26, p  = 0.014) 0.02 (−1.22; 1.26, p = 0.976) 0.33 (CI 0.07; 0.59, p = 0.015)	0.0002
IMFA, cm^2 Ethnicity European vs Inuit Age (per year) Height (per cm) Sex women vs men	1.7 (CI −1.3; 4.7, p = 0.263) 0.1 (CI −0.005; 0.2, p = 0.059) 5.8 (CI −17.7; 29.3, p = 0.624) 0.2 (CI −4.7; 5.1, p = 0.940)	0.1206
IMFD, HU Ethnicity European vs Inuit Age (per year) Height (per cm) Sex women vs men	−8.0 (CI −11.8; −4.2, p <0.0001) −0.03 (CI −0.2; 0.1, p = 0.691) 0.3 (−29.0; 29.5, p = 0.986) −1.0 (CI −11.8; −4.2, p = 0.743)	0.0015

CI: confidence interval, HU: Hounsfield Unit, IMFA: Inter and intramuscular fat area, IMFD: Inter and intramuscular fat density, SMD: Skeletal muscle density, SMI: Skeletal muscle index, SFA: Subcutaneous fat area, SFD: Subcutaneous fat density, SFI: Subcutaneous fat index, VFA: Visceral fat area, VFD: visceral fat density, VFI: Visceral fat index.

Data availability statement

Data is not available due to ethical and legal data policies.