Chronic obstructive pulmonary disease phenotypes and balance impairment

Figures & data

Table 1 Comparison of studied parameters between the three groups

Parameter	A	B	C	P-value (A vs B vs C)§
	Controls (n=17)	Emphysematous COPD (n=13)	Bronchitic COPD (n=14)
Age§	61.3±4.0	64.1±2.6	63.9±1.9	0.087
BMI§	25.3±3.9	17.6±0.8	36.1±3.3	<0.001*
FFM (%)¥	77.1 (5.5)	87.2 (10.1)	58.9 (9.6)	<0.001*
Body fat (%)¥	18.2 (8.8)	10.2 (7.4)	37.3 (4.1)	<0.001*
FVC (%)¥	95 (15)	70 (10)	68 (9)	<0.001*
FEV1 (%)¥	95 (18)	31 (2)	30 (4)	<0.001*
FVC/FEV1 ¥	79 (9)	41 (7)	41 (8)	<0.001*

Notes: Values are presented as median and (interquartile range) – non-Gaussian distributions or average ± standard deviation – Gaussian distributions.

* Differences are significant.

§ P-value was calculated using ANOVA test.

¥ P-value was calculated using Kruskal–Wallis test.

Abbreviations: ANOVA, analysis of variance; BMI, body mass index; COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 second; FFM, fat-free mass; FVC, forced vital capacity.

Figure 1 Comparison of timed up and go test between study subcohorts.

Abbreviation: COPD, chronic obstructive pulmonary disease.

Table 2 Balance parameters in the three subgroups

Parameter	A	B	C	P-value (A vs B vs C)§
	Controls (n=17)	Emphysematous COPD (n=13)	Bronchitic COPD (n=14)
CAT		20 (11)	18 (13)	<0.001
6MWD (m)	521 (92)	420 (148)	321.5 (193)	<0.001
BBS (points)	55 (2)	45 (14)	45.5 (9)	<0.001
TUG (seconds)	8.6 (2.5)	12.8 (1.25)	14.7 (2.5)	<0.001
SLS (seconds)	31.1 (16)	15.6 (6)	8.7 (6)	<0.001
ABC (%)	97.9 (4)	74.2 (12)	53.2 (20)	<0.001

Notes: Variables are not-Gaussian distributed. Values are presented as median and (interquartile range).

§ P-value was calculated using Kruskal–Wallis test.

Abbreviations: ABC, activities balance confidence; BBS, Berg Balance Scale; CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; 6MWD, 6-minute walking distance; SLS, single leg stance; TUG, timed up and go.

Table 3 Correlations between FFM and balance parameters

Studied parameters	FFM (kg) – left leg	FFM (kg) – right leg	FFM (%)	BMI
CAT	−0.055	−0.066	−0.089	−0.127
6MWD (m)	−0.338	−0.319	0.386**	−0.355
BBS (points)	−0.079	−0.049	0.034	0.103
TUG (seconds)	0.608**	0.594**	−0.408**	0.621**
SLS (seconds)	−0.639**	−0.640**	0.472**	−0.681**
ABC (%)	−0.608**	−0.632**	0.404**	−0.586**

Notes: Correlations strengths were assessed using Spearman’s rank sum correlation coefficient.

** Correlation is significant at α<0.01 level.

Abbreviations: ABC, activities balance confidence; BBS, Berg Balance Scale; BMI, body mass index; CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; FFM, fat-free mass; 6MWD, 6-minute walking distance; SLS, single leg stance; TUG, timed up and go.

Figure 2 The interrelationship between the percentage of fat-free mass and ABC (%).

Abbreviation: ABC, activities balance confidence.

Table 4 Correlations among respiratory, inflammatory, and balance parameters

Studied parameters	FVC (%)	FEV1 (%)	CRP	Fibrinogen
CAT	−0.243	0.413*	0.402*	0.521**
6MWD (m)	0.147	−0.035	−0.557**	−0.366
BBS (points)	0.588**	−0.346	−0.257	−0.242
TUG (seconds)	−0.145	−0.288	0.166	−0.017
SLS (seconds)	0.117	0.288	−0.241	0.075
ABC (%)	0.212	0.159	0.159	0.296

Notes: Correlations strengths were assessed using Spearman’s rank sum correlation coefficient.

* Correlation is significant at α<0.05 level.

** Correlation is significant at α<0.01 level.

Abbreviations: ABC, activities balance confidence; BBS, Berg Balance Scale; CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; CRP, C-reactive protein; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; 6MWD, 6-minute walking distance; SLS, single leg stance; TUG, timed up and go.