Longitudinal Relationship Between Growth Differentiation Factor 11 and Physical Activity in Chronic Obstructive Pulmonary Disease

Figures & data

Table 1 Characteristics of the Study Subjects

Subjects, n	24
Age, years	72.2	±	6.7
Males/females	23/1
Smoking, pack-years	57.0	±	20.8
BMI, kg/m^2	21.8	±	3.1
mMRC scale	1.4	±	1.2
FVC, % predicted	88.8	±	18.8
FEV1, % predicted	54.4	±	19.5
FEV1/FVC, %	48.9	±	14.7
IC, L	2.1	±	0.5
DLco, % predicted	54.6	±	30.5
GOLD (I/II/III/IV)	(2/11/8/3)
Steps per day	2846 (2191–4809)
6MWD, m	396 (291–486)
LABA, n	18
LAMA, n	22
ICS, n	4

Note: Data are presented as mean ± SD or median (with interquartile ranges).

Abbreviations: BMI, body mass index; mMRC, modified Medical Research Council; FVC, forced vital capacity; FEV₁, forced expiratory volume in one second; IC, inspiratory capacity; D_Lco, diffusing capacity of the lung for carbon monoxide which was measured with a single-breath method and calculated simultaneously with the measured alveolar volume; GOLD, Global Initiative for Chronic Obstructive Lung Disease; 6MWD, six-minutes walking distance; LABA, long-acting β₂ agonist; LAMA, long-acting muscarinic antagonist; ICS, inhaled corticosteroids.

Figure 1 Longitudinal association between the plasma level of GDF11 and physical activity.

Notes: Correlations between the plasma levels of GDF11 and the parameters of physical activity including the number of steps (A), duration ≥3.0 METs (B), ≥2.5 METs (C) and ≥2.0 METs (D) were investigated. r is the correlation coefficient. Delta (∆) means change in values between baseline and follow-up. Data were statistically analyzed by the Spearman’s rank test.

Abbreviations: GDF11, growth differentiation factor 11; METs, metabolic equivalents.

Figure 2 Longitudinal relationship between systemic inflammatory markers and physical activity.

Notes: Correlations between the amounts of IL-6 (A), hs-CRP (B) and MDA (C) and the parameter of physical activity with the number of steps were investigated. Delta (∆) means change in values between baseline and follow-up. r is the correlation coefficient. Data were analyzed by the Spearman’s rank test.

Abbreviations: hs-CRP, high sensitivity C-reactive protein; IL-6, interleukin-6; MDA, malondialdehyde.

Table 2 Multiple Regression Analysis of the Changes in Physical Activity in the Patients with COPD

	Change in Number of Steps
Variables	β	p value
Age	0.26	0.259
BMI	−0.22	0.221
mMRC scale	−0.17	0.371
∆FEV1	0.26	0.209
∆IC	0.24	0.258
∆GDF11	0.93	<0.001
∆IL-6	−0.20	0.298

Notes: β = standardized regression coefficient. Delta (∆) means change in values between baseline and follow-up. Data were analyzed by multivariate linear regression. R² = 0.71 (adjusted R² = 0.56).

Abbreviations: BMI, body mass index; mMRC, modified Medical Research Council; FEV₁, forced expiratory volume in one second; IC, inspiratory capacity; GDF11, growth differentiation factor 11; IL-6, interleukin-6.

Figure 3 Relationship between maintained plasma level of GDF11 and the exacerbation of COPD.

Notes: Data represent the median (with interquartile ranges). Data were analysed using Wilcoxon Rank-Sum tests. P values less than 0.05 were considered significant.

Abbreviation: GDF11, growth differentiation factor 11.