Relation between systemic inflammatory markers, peripheral muscle mass, and strength in limb muscles in stable COPD patients

Figures & data

Table 1 Characteristics of the COPD patients in total group and according to GOLD classification

Variables	Total group (n=55)	COPD I/II (n=29)	COPD III/IV (n=26)	P-value
Age, years	64.0±9.2	63.3±10.0	66.0±8.3	0.29
Sex (F/M), n	17/38	11/18	6/20	0.36
FEV1(%)*	51.0 (39.2–66.2)	64.0 (55.7–78.5)	38.5 (29.0–42.0)	<0.001
Active smoking, n	15	8	7	0.80
6MWD (m)	440.3±85.8	447.2±96.6	432.7±73.0	0.53
MRC score	1.0 (1.0–2.0)	1.0 (1.0–1.2)	1.0 (1.0–2.0)	0.08
BMI (kg/m^2)	25.4±5.1	26.4±5.6	24.2±4.2	0.10
FFM (kg)	41.4±7.2	41.8±6.8	41.0±7.6	0.71
FFM index (kg/m^2)	16.0 (14.8–17.6)	16.9 (14.8–17.6)	15.8 (15.0–17.6)	0.53
MACSA (cm^2)	35.7±9.3	36.7±9.0	34.6±9.8	0.41
MTCSA (cm^2)	122.7±26.9	126.2±28.4	118.8±25.1	0.31
Leg extension (kg)	80.0 (65.0–100.0)	90.0 (70.0–104.5)	77.5 (60.0–95.0)	0.09
Biceps curl (kg)	20.0 (16.0–24.0)	20.0 (18.0–24.0)	20.0 (14.0–23.0)	0.60
Triceps pulley (kg)	18.4±5.6	19.1±5.5	17.5±5.7	0.29
TNF-α (pg/mL)	4.3 (4.0–4.7)	4.5 (4.2–4.8)	4.1 (3.8–4.4)	0.05
IL-8 (pg/mL)	5.3 (3.7–15.5)	5.1 (3.4–21.2)	5.3 (3.9–10.6)	0.74
CRP (mg/L)	5.9 (2.7–9.3)	4.4 (2.6–7.9)	6.8 (2.8–9.7)	0.45

Notes: Values are presented as mean ± SD or median (interquartile range). P<0.05 (Student’s t-test or Mann–Whitney and chi-square). COPD I/II indicates mild/moderate disease, according to GOLD classification; COPD III/IV indicates severe/very severe.

* Expressed as percentage of predicted.

Abbreviations: 6MWD, six-minute walking distance test; BMI, body mass index; F, Female; FEV₁, forced expiratory volume in the first second; FFM, fat-free mass; GOLD, Global Initiative for Chronic Obstructive Lung Disease; M, Male; MACSA, midarm cross-sectional muscle area; MRC, Modified Medical Research Council dyspnea scale; MTCSA, midthigh cross-sectional muscle area; SD, standard deviation.

Table 2 Linear regression models, with robust standard errors, for 1 RM leg extension, 1 RM triceps pulley, and 1 RM biceps curl

Model	Variables	Coefficient (95% CI)	P-value
1 RM leg extension	Age, years	0.19 (−0.13, 0.52)	0.23
	Sex, Male	5.20 (−4.23, 14.66)	0.27
	FEV1 (%)*	−0.11 (−0.23, 0.01)	0.07
	MTCSA (cm^2)	0.35 (0.16, 0.55)	0.001**
	TNF-α (pg/mL)	−3.09 (−5.99, −0.18)	0.04**
1 RM triceps pulley	Age, years	−0.42 (−0.21, 0.13)	0.62
	Sex, Male	−0.73 (−4.18, 2.71)	0.67
	FEV1 (%)*	0.19 (−0.02, 0.06)	0.38
	MACSA (cm^2)	0.45 (0.31, 0.58)	0.001**
	TNF-α (pg/mL)	−1.31 (−2.35, −0.28)	0.01**
1 RM biceps curl	Age (years)	0.03 (−0.14, 0.21)	0.68
	Male sex	−2.46 (−6.01, 1.07)	0.17
	FEV1 (%)*	0.02 (−0.02, 0.07)	0.28
	MACSA (cm^2)	0.34 (0.22, 0.47)	0.001**
	CRP (mg/L)	−0.06 (−0.11, −0.01)	0.02**

Notes: P<0.05 (multiple linear regression with robust standard errors).

* Expressed as percentage of predicted.

** Significant.

Abbreviations: 1 RM, one-repetition maximum; CI, confidence interval; FEV₁, forced expiratory volume in the first second (% of predicted); MACSA, midarm cross-sectional muscle area; MTCSA, midthigh cross-sectional muscle area.