Phase angle and non-alcoholic fatty liver disease before and after bariatric surgery

Table 1 Sample characteristics, n = 379

Variables	n = 379
Gender, n (%)
Male	78 (20.6)
Female	301 (79.4)
Age in yr, mean ± SD	39.1 ± 10.6
Weight in kg, mean ± SD	123.7 ± 24.8
Minimum	77
Maximum	235
BMI in kg/m2, mean ± SD	45.9 ± 7.5
BMI classification, n (%)
30-34.99 kg/m²	3 (0.8)
35-39.99 kg/m²	82 (21.6)
40-49.99 kg/m²	210 (55.4)
50 kg/m² or more	84 (22.2)
SMM in kg, mean ± SD	34.1 ± 7.5
BCM in kg, mean ± SD	39.4 ± 8.3
Fat mass in kg, mean ± SD	62.6 ± 15.1
% Fat-mean ± SD	50.7 ± 4.6
Visceral fat area in cm², mean ± SD	243.7 ± 31.2
Phase angle °, mean ± SD
Full-body	5.89 ± 0.62
RA	5.58 ± 0.62
LA	5.42 ± 0.65
Tr	7.97 ± 1.18
RL	6.14 ± 0.81
LL	6.07 ± 0.84

BCM: Body cell mass; BMI: Body mass index; LA: Left arm; LL: Left leg; RA: Right arm; RL: Right leg; SD: Standard deviation; SMM: Skeletal muscle mass; Tr: Torso.

Table 2 Sample characteristics for liver disease, n = 379

Variables	n (%)
NAFLD
Yes	379 (100.0)
No	0 (0.0)
Hepatic steatosis
Absent	0 (0.0)
Discreet	159 (42.0)
Moderate	104 (27.4)
Accented	84 (22.2)
Massive	32 (8.4)
Ballooning
Absent	91 (24.0)
Discreet	221 (58.3)
Moderate	18 (4.7)
Accented	49 12.9)
Massive	0 (0.0)
Lobular inflammation
Absent	243 (64.1)
Discreet	100 (26.4)
Moderate	28 (7.4)
Accented	8 (2.1)
Massive	0 (0.0)
NASH
Absent	83 (21.9)
Grade 1	201 (53.0)
Grade 2	67 (17.7)
Grade 3	28 (7.4)
Grade 4	0 (0.0)
Absent	216 (57.0)
Grade 1	86 (22.7)
Grade 2	44 (11.6)
Grade 3	33 (8.7)
Grade 4	0 (0.0)
Cirrhosis
Yes	0 (0.0)
No	379 (100.0)

NAFLD: Non-alcoholic fatty liver disease; NASH: Non-alcoholic steatohepatitis.

Table 3 Variation of body composition before and after bariatric surgery, n = 379

Variables	Pre	Post	P value
	mean ± SD	mean ± SD
BMI in kg/m²	45.9 ± 7.5	31.2 ± 5.0	< 0.001
SMM in kg	34.1 ± 7.5	29.0 ± 6.4	< 0.001
BCM in kg	39.4 ± 8.3	33.9 ± 6.9	< 0.001
Fat mass in kg	62.6 ± 15.1	31.9 ± 11.1	< 0.001
% Fat	50.7 ± 4.6	37.2 ± 8.1	< 0.001
Visceral fat area in cm²	243.7 ± 31.2	152.0 ± 51.0	< 0.001

BCM: Body cell mass; BMI: Body mass index; SD: Standard deviation; SMM: Skeletal muscle mass.

Table 4 Association of body composition variables with phase angle in men and women, using Pearson’s correlation coefficient, n = 379

Variables	Weight in kg	SMM in kg	BCM in kg	Fat mass in kg	% Fat	Visceral fat area in cm²
Male gender, n = 78
PA full body	-0.418c	-0.118	-0.101	-0.469c	-0.401c	-0.075
PA RA	-0.299b	-0.083	-0.064	-0.337b	-0.287a	-0.095
PA LA	-0.286a	-0.031	-0.008	-0.349b	-0.341b	-0.136
PA Tr	-0.074	0.074	0.094	-0.134	-0.185	0.311b
PA RL	-0.493c	-0.179	-0.170	-0.531c	-0.421c	-0.101
PA LL	-0.509c	-0.211	-0.209	-0.534c	-0.403c	-0.066
Female gender, n = 301
PA full body	-0.106	0.125a	0.122b	-0.152b	-0.393c	-0.098
PA RA	0.011	0.169b	0.148a	-0.036	-0.245c	-0.111
PA LA	0.043	0.193b	0.155b	-0.009	-0.226c	-0.135a
PA Tr	0.024	0.120a	0.133a	-0.030	-0.172b	-0.058
PA RL	-0.154b	0.083	0.068	-0.182b	-0.406c	-0.043
PA LL	-0.151b	0.069	0.052	-0.187b	-0.388c	-0.086

^aP < 0.05.

^bP < 0.01.

^cP < 0.001. BCM: Body cell mass; LA: Left arm; LL: Left leg; PA: Phase angle; RA: Right arm; RL: Right leg; SMM: Skeletal muscle mass; Tr: Torso.

Table 5 Variation of phase angle in the pre- and postoperative period of bariatric surgery, n = 169

Variables	Pre	Post	P value
	mean ± SD	mean ± SD
PA full body	5.92 ± 0.55	4.98 ± 0.55	< 0.001
PA RA	5.58 ± 0.60	4.73 ± 0.59	< 0.001
PA LA	5.42 ± 0.63	4.54 ± 0.57	< 0.001
PA Tr	7.87 ± 1.15	6.76 ± 1.29	< 0.001
PA RL	6.25 ± 0.66	5.19 ± 0.65	< 0.001
PA LL	6.18 ± 0.70	5.14 ± 0.66	< 0.001

LA: Left arm; LL: Left leg; PA: Phase angle; RA: Right arm; RL: Right leg; SD: Standard deviation; Tr: Torso.

Table 6 Association of body mass index with phase angle through Pearson correlation, n = 169

Variables	BMI
	r	P value
PA full body	-0.121	0.018
PA RA	0.031	0.551
PA LA	0.057	0.265
PA Tr	0.054	0.298
PA RL	-0.262	< 0.001
PA LL	-0.262	< 0.001

BMI: Body mass index; LA: Left arm; LL: Left leg; PA: Phase angle; r: Pearson's correlation coefficient; RA: Right arm; RL: Right leg; Tr: Torso.

Table 7 Degrees and staging of non-alcoholic fatty liver disease before and after bariatric surgery, n = 33

Variables	Pre	Post	P value
	n (%)	n (%)
NAFLD			0.031
Yes	33 (100)	27 (81.8)
No	0 (0.0)	6 (18.2)
Hepatic steatosis			< 0.001
Absent	0 (0.0)	6 (18.2)
Discreet	14 (42.4)	24 (72.7)
Moderate	8 (24.2)	3 (9.1)
Accented	8 (24.2)	0 (0.0)
Massive	3 (9.1)	0 (0.0)
Ballooning			< 0.001
Absent	5 (15.2)	29 (87.9)
Discreet	23 (69.7)	4 (12.1)
Moderate	3 (9.1)	0 (0.0)
Accented	2 (6.1)	0 (0.0)
Lobular inflammation			0.003
Absent	21 (63.6)	30 (90.9)
Discreet	7 (21.2)	3 (9.1)
Moderate	3 (9.1)	0 (0.0)
Accented	2 (6.1)	0 (0.0)
NASH			< 0.001
Absent	6 (18.2)	25 (75.8)
Grade 1	20 (60.6)	5 (15.2)
Grade 2	4 (12.1)	3 (9.1)
Grade 3	3 (9.1)	0 (0.0)
Fibrosis			0.033
Absent	26 (78.8)	27 (81.8)
Grade 1	3 (9.1)	4 (12.1)
Grade 2	0 (0.0)	0 (0.0)
Grade 3	4 (12.1)	2 (6.1)

NAFLD: Non-alcoholic fatty liver disease; NASH: Non-alcoholic steatohepatitis.

Table 8 Phase angle and body composition in patients who underwent liver biopsy after bariatric surgery, n = 33

Variables	Pre	Post	P value
	mean ± SD	mean ± SD
BMI in kg/m²	45.2 ± 6.9	31.8 ± 5.4	< 0.001
SMM in kg	31.9 ± 6.8	27.1 ± 5.3	< 0.001
BCM in kg	37.0 ± 7.8	32.1 ± 5.9	< 0.001
Fat mass in kg	60.7 ± 13.3	33.6 ± 11.1	< 0.001
% Fat	51.6 ± 3.5	39.8 ± 8.2	< 0.001
Visceral fat area in cm²	249.3 ± 23.1	162.5 ± 52.3	< 0.001
PA full body °	5.93 ± 0.65	4.91 ± 0.60	< 0.001
PA RA °	5.55 ± 0.77	4.61 ± 0.64	< 0.001
PA LA °	5.44 ± 0.86	4.44 ± 0.58	< 0.001
PA Tr °	7.84 ± 1.24	6.73 ± 1.03	< 0.001
PA RL °	6.42 ± 0.72	5.18 ± 0.68	< 0.001
PA LL °	6.38 ± 0.74	5.19 ± 0.66	< 0.001

BCM: Body cell mass; BMI: Body mass index; LA: Left arm; LL: Left leg; PA: Phase angle; RA: Right arm; RL: Right leg; SMM: Skeletal muscle mass; Tr: Torso.