Evaluation of body composition in COPD patients using multifrequency bioelectrical impedance analysis

Figures & data

Table 1 General characteristics of 212 COPD patients and 115 controls studied

Characteristics	Males (N=197)			Females (N=130)
	COPD (N=144)	Controls (N=53)	P-value	COPD (N=68)	Controls (N=62)	P-value
Age (years)	70.3±7.3	68.5±7.8	ns	69.1±8.2	68.7±7.0	ns
Height (cm)	165.4±7.0	167.5±6.9	ns	152.3±6.4	156.9±7.5	<0.001
Weight (kg)	71.4±12.6	75.3±9.3	<0.05	62.7±10.7	68.0±8.4	<0.005
BMI (kg/m^2)	26.0±3.9	26.7±2.4	ns	27.0±4.6	27.6±2.7	ns
FFM (kg)	53.0±7.2	57.6±7.4	<0.001	40.3±3.6	45.3±5.5	<0.001
FFMI (kg/m^2)	19.3±1.4	20.5±1.7	<0.001	17.4±1.3	18.3±1.3	<0.001
FM (kg)	18.4±7.2	17.7±5.3	ns	22.4±7.8	22.8±5.4	ns
FMI (kg/m^2)	6.7±2.5	6.3±1.9	ns	9.7±3.3	9.3±2.1	ns
5/250 impedance ratio	124.1±4.9	126.8±4.7	<0.001	122.3±4.1	126.0±3.5	<0.001

Note: Data are presented as mean ± standard deviation.

Abbreviations: BMI, body mass index; FFM, fat-free mass; FFMI, fat-free mass index; FM, fat mass; FMI, fat mass index; 5/250 impedance ratio, ratio between Z at 5 kHz and Z at 250 kHz; ns, not significant.

Table 2 General characteristics and body composition of COPD patients stratified according to the median value of the 5/250 impedance ratio

Characteristics	Z 5/250 impedance ratio
	Males			Females
	Below median value (n=72)	Above median value (n=72)	P-value*	Below median value (n=34)	Above median value (n=34)	P-value*
Age (years)	71.7±7.6	69.0±6.8	<0.05	71.3±8.2	67.1±7.6	<0.05
Weight (kg)	68.7±14.6	74.0±13.3	<0.05	61.7±17.4	64.5±10.1	ns
BMI (kg/m^2)	25.2±3.8	26.9±3.9	<0.005	26.4±4.0	27.6±4.7	ns
FFMI (kg/m^2)	19.0±2.0	19.7±1.9	<0.05	17.4±2.4	17.5±1.4	ns
FMI (kg/m^2)	6.3±2.5	7.1±2.2	<0.05	10.2±6.9	10.1±3.4	ns
HGS (kg)	25.7±5.7	33.0±7.0	<0.001	16.1±3.3	22.0±4.9	<0.001
6MWD (min)	0; 348	300; 434	<0.005	0; 60	240; 349	<0.05

Notes: Data are presented as mean ± standard deviation for all variables, except for 6MWD (as interquartile range). Median value for 5/250 impedance ratio: 124.4 for males; 122.7 for females.

* P<0.05.

Abbreviations: 5/250 impedance ratio, ratio between Z at 5 kHz and Z at 250 kHz; BMI, body mass index; FFMI, fat-free mass index; FMI, fat mass index; HGS, handgrip strength – dominant side; 6MWD, 6-minute walk distance; ns, not significant.

Table 3 Respiratory parameters of 212 COPD patients stratified according to the median value of 5/250 impedance ratio (124.4 for males; 122.7 for females)

Characteristics	5/250 impedance ratio
	Below median value (n=106)	Above median value (n=106)	P-value*
FEV1 (% predicted)	42.5±18.3	47.7±19.3	<0.05
VC (% predicted)	66.0±17.8	73.3±19.0	<0.005
RV (% predicted)	243.1±66.7	258.9±68.6	ns
ITGV (% predicted)	183.3±49.1	195.1±48.9	ns
IC/TLC	0.3±0.8	0.2±0.3	ns
MIP (cm·H2O)	49.9±17.7	61.7±20.8	<0.001
MEP (cm·H2O)	72.2±24.2	84.5±27.3	<0.001
MRC dyspnea scale	3.8±0.4	3.6±0.5	<0.05

Notes: Data are presented as mean ± standard deviation.

* P<0.05.

Abbreviations: 5/250 impedance ratio, ratio between Z at 5 kHz and Z at 250 kHz; FEV₁, forced expiratory volume in 1 second; VC, vital capacity; RV, residual volume; ITGV, intrathoracic gas volume; IC, inspiratory capacity; TLC, total lung capacity; MIP, maximum inspiratory pressure; MEP, maximum expiratory pressure; MRC, Medical Research Council; ns, not significant.

Figure 1 (A) Relationship between 5/250 impedance ratio and MIP in 212 COPD patients (males in black, females in white) (r=0.471, P<0.001); (B) relationship between 5/250 impedance ratio and MEP in 212 COPD patients (males in black, females in white) (r=0.411, P<0.001).

Abbreviations: MIP, maximum inspiratory pressure; MEP, maximum expiratory pressure.