Association Between Anthropometric Indices and Skeletal-Muscle Atrophy in Chinese Patients with Stable Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study

Figures & data

Table 1 Patient Characteristics (n = 123)

Variables	Mean ± SD
Age (y)	66.74 ± 7.32
BMI (kg/m^2)	22.49 ± 3.69
FEV1 (% predicted)	47.35 ± 18.37
FEV1/FVC	47.11 ± 12.52
FFM (kg)	48.57 ± 6.79
ASM (kg)	22.70 ± 3.25
FFMI (kg/m^2)	17.49 ± 1.86
ASMI (kg/m^2)	8.17 ± 0.90
TSF (cm)	1.08 ± 0.44
MAC (cm)	26.39 ± 2.92
MAMC (cm)	23.01 ± 2.15
MAMA (cm^2)	42.51 ± 7.98
CC (cm)	34.53 ± 3.06

Note: Data are expressed as the mean (standard deviation [SD]).

Abbreviations: BMI, body mass index; FEV_1, forced expiratory volume in 1s; FVC, forced vital capacity; FFM, fat-free mass; FFMI, fat-free mass index; ASM, appendicular skeletal-muscle mass; ASMI, appendicular skeletal-muscle mass index; TSF, triceps skinfold; MAC, midarm circumference; CC, calf circumference; MAMC, midarm muscle circumference; MAMA, midarm muscle area.

Table 2 Comparison of Skeletal-Muscle Mass with Baseline Characteristics

Variables	Number (n, %)	FFM (kg)	FFMI (kg/m^2)	ASM (kg)	ASMI (kg/m^2)
Age (y)
≤60	23 (18.70)	54.07 ± 5.22	18.63 ± 1.54	25.09 ± 2.65	8.64 ± 0.79
>60	100 (81.30)	47.31 ± 6.49	17.23 ± 1.83	22.15 ± 3.14	8.06 ± 0.89
t		4.657	3.403	4.158	2.867
P		<0.001	<0.001	<0.001	0.005
Sex
Male	116 (94.31)	49.14 ± 6.47	17.59 ± 1.82	22.96 ± 3.11	8.22 ± 0.88
Female	7 (5.69)	39.14 ± 5.10	15.83 ± 1.80	18.27 ± 2.47	7.39 ± 0.88
t		4.011	2.491	3.917	2.424
P		<0.001	0.014	<0.001	0.017
Smoking status
Never smoker	13 (10.57)	46.85 ± 7.45	17.39 ± 1.66	21.88 ± 3.50	8.13 ± 0.78
Ex-smoker	71 (57.72)	49.46 ± 6.51	17.66 ± 1.88	23.12 ± 3.10	8.26 ± 0.90
Current smoker	39 (31.71)	47.53 ± 6.98	17.21 ± 1.87	22.19 ± 3.41	8.03 ± 0.94
F		1.501	0.765	1.496	0.781
P		0.227	0.468	0.228	0.460
BMI (kg/m^2)
<21	43 (34.96)	44.74 ± 5.89	15.87 ± 1.28	20.99 ± 2.97	7.44 ± 0.70
21–25	52 (42.28)	48.75 ± 5.79	17.65 ± 1.11	22.69 ± 2.76	8.22 ± 0.56
25–30	25 (20.32)	53.55 ± 5.95	19.46 ± 1.03	25.04 ± 2.82	9.10 ± 0.49
≥30	3 (2.44)	58.87 ± 4.40	21.60 ± 0.77	27.60 ± 2.07	10.13 ± 0.42
F		15.350	65.652	13.875	52.144
P		<0.001	<0.001	<0.001	<0.001
Duration (y)
< 5	70 (56.91)	48.43 ± 6.65	17.48 ± 1.86	22.55 ± 3.16	8.14 ± 0.89
5–15	33 (26.83)	48.10 ± 7.01	17.34 ± 1.80	22.61 ± 3.44	8.15 ± 0.89
> 15	20 (16.26)	49.86 ± 7.10	17.79 ± 2.01	23.34 ± 3.36	8.33 ± 0.96
F		0.451	0.379	0.466	0.368
P		0.638	0.685	0.628	0.693
MMRC score
0	14 (11.38)	52.86 ± 7.74	18.38 ± 1.93	24.76 ± 3.70	8.61 ± 0.93
1	78 (63.41)	49.02 ± 6.80	17.62 ± 1.87	22.90 ± 3.28	8.23 ± 0.92
2	23 (18.70)	45.22 ± 4.85	16.84 ± 1.50	21.09 ± 2.29	7.85 ± 0.71
3	8 (6.51)	46.34 ± 5.33	16.51 ± 1.82	21.71 ± 2.41	7.74 ± 0.82
F		4.482	3.056	4.457	2.981
P		0.005	0.031	0.005	0.034
GOLD stage 2011
A	3 (2.44)	53.60 ± 8.41	18.81 ± 1.28	25.10 ± 3.93	8.81 ± 0.59
B	37 (30.08)	50.46 ± 4.93	18.12 ± 1.22	23.45 ± 2.40	8.42 ± 0.63
C	3 (2.44)	58.40 ± 5.13	20.80 ± 2.14	27.37 ± 2.44	9.75 ± 1.05
D	80 (65.04)	47.14 ± 7.02	17.02 ± 1.90	22.08 ± 3.39	7.97 ± 0.92
F		5.286	8.000	4.600	6.717
P		0.002	<0.001	0.004	<0.001
GOLD stage 2017
A	4 (3.25)	56.00 ± 8.38	19.58 ± 1.85	26.20 ± 3.89	9.16 ± 0.85
B	86 (69.92)	48.38 ± 6.14	17.55 ± 1.78	22.60 ± 2.99	8.19 ± 0.87
C	0 (0)	–	–	–	–
D	33 (26.83)	48.18 ± 7.87	17.09 ± 1.93	22.53 ± 3.70	7.99 ± 0.91
F		2.547	3.462	2.459	3.205
P		0.083	0.035	0.090	0.044

Notes: Smoking status, BMI, disease duration, MMRC, and GOLD stage were assessed using one-way analysis of variance. Other parameters were compared using t-tests.

Abbreviations: FFM, fat-free mass, FFMI, fat-free mass index; ASM, appendicular skeletal-muscle mass; ASMI, appendicular skeletal-muscle mass index; MMRC, modified Medical Research Council scale; GOLD, Global Initiative for Chronic Obstructive Lung Disease.

Table 3 Correlations Between Anthropometric Data and Skeletal-Muscle Mass

Variables	FFMI	ASMI
TSF (cm)	0.500**	0.481**
MAC (cm)	0.752**	0.714**
MAMC (cm)	0.703**	0.663**
MAMA (cm^2)	0.698**	0.659**
CC (cm)	0.820**	0.800**

Note: **P < 0.01.

Abbreviations: FFMI, fat-free mass index; ASMI, appendicular skeletal-muscle mass index; TSF, triceps skinfold; MAC, midarm circumference; MAMC, midarm muscle circumference; MAMA, midarm muscle area; CC, calf circumference.

Table 4 Multiple-Regression Analysis of Factors Associated with FFMI or ASMI

Variables	FFMI				Variables	ASMI
	B	SE	t	P		B	SE	t	P
CC (cm)	0.254	0.420	6.615	0.000	CC (cm)	0.134	0.455	6.140	0.000
BMI (kg/m^2)	0.971	0.420	6.342	0.000	BMI (kg/m^2)	0.436	0.390	5.032	0.000
MAC (cm)	0.182	0.208	3.946	0.000	TSF (cm)	−0.365	−0.178	−2.514	0.013
TSF (cm)	−0.880	−0.208	−3.477	0.001	MAC (cm)	0.063	0.206	2.325	0.022

Abbreviations: SE, standard error; CC, calf circumference; BMI, body mass index; MAC, midarm circumference; TSF, triceps skinfold.

Table 5 Anthropometric Data for Evaluating Skeletal-Muscle Atrophy in Stable COPD Patients

Variables	Cutoff Value	Sensitivity (%)	Specificity (%)	AUC
FFMI
MAC (cm)	24.50	92	81.6	0.932
MAMC (cm)	22.19	88	76.5	0.886
MAMA (cm^2)	39.21	88	76.5	0.886
CC (cm)	33.00	92	85.7	0.942
ASMI
MAC (cm)	23.65	88.9	84.2	0.910
MAMC (cm)	22.09	100	70.2	0.873
MAMA (cm^2)	38.86	100	70.2	0.873
CC (cm)	31.80	100	86.8	0.959

Abbreviations: AUC, area under the curve; FFMI, fat-free mass index; MAC, midarm circumference; MAMC, midarm muscle circumference; MAMA, midarm muscle area; CC, calf circumference; ASMI, appendicular skeletal-muscle mass index.

Figure 1 Receiver operating characteristic curve of anthropometric data for evaluating skeletal-muscle atrophy (fat-free mass index [FFMI]).

Figure 2 Receiver operating characteristic curve of anthropometric data for evaluating skeletal-muscle atrophy (appendicular skeletal-muscle mass index [ASMI]).