Handgrip Strength Seems Not to Be Affected by COPD Disease Progression: A Longitudinal Cohort Study

Figures & data

Figure 1. Study flow. LTx: lung transplantation; HGS: handgrip strength.

Table 1. Patient characteristics.

N = 194
Age (years)		64 (59, 69)
Male/Female, N (%)		127 (65)/68 (35)
BMI (kg/m^2)		26 (22.7, 28.4)
Current smoker, N (%)		49 (25)
Pack years of smoking, N		40 (30, 60)
GOLD stage	1, N (%)	18 (9)
	2, N (%)	71 (37)
	3, N (%)	74 (38)
	4, N (%)	31 (16)
FEV1 (% pred.)		46 (34, 65)
RV/TLC (%)		54 (46, 61.5)
Frequent exacerbators, N (%)		44 (23)
mMRC (N)		1.5 (0.99)
Number of musculoskeletal comorbidities (N)		0.80 (0.93)
Handgrip strength in kg, dominant		35.3 (28.2, 44.4)
Handgrip strength (% pred.)		50 (25, 90)
6MWD (m)		448 (360, 510)
Steps per day (N)		4584 (2671, 7220)

Values are median (quartiles) or mean (SD) unless otherwise stated. BMI: body mass index; kg/m²: kilogram per square meter; FEV₁: forced expiratory volume in one second; RV/TLC: residual volume to total lung capacity; mMRC: modified medical research council.

Table 2. Univariate mixed effect analysis of possible predictors for handgrip strength (kg) decline over time, dominant side.

	B	95% CI	p value
BMI (kg/m^2)	−2.20	−0.09/0.01	0.028
ExSmoker	0.23	−0.45/0.90	0.507
Smoker	−0.43	−1.15/0.29	0.238
Pack years (N)	−0.01	−0.02/0.00	0.093
FEV1 (% pred.)	0.02	0.00/0.03	0.015
RV/TLC (%)	−0.01	−0.03/0.01	0.295
TLco (% pred.)	−0.00	−0.02/0.01	0.508
Number of musculoskeletal comorbidities (N)	0.13	−1.11/1.36	0.841
Frequent exacerbators	−0.10	−0.64/0.43	0.702
Number of exacerbations (N)	−0.05	−0.25/0.15	0.625
Severe exacerbations (N)	−0.39	−0.94/0.17	0.176
Non-survivor vs. survivor	0.18	−2.24/2.60	0.884
Survival time (months)	0.01	−0.01/0.02	0.343
CAT, points	−0.03	−0.07/0.00	0.065
PaO2 (kPa)	0.15	−0.00/0.30	0.054
PaCO2 (kPa)	−0.22	−0.58/0.14	0.229
CRP	−0.01	−0.03/0.02	0.502
6MWD (m)	0.00	−0.00/0.00	0.115
1MSTS (repetitions)	0.02	−0.01/0.05	0.262
Steps per day, N/1000	0.07	0.01/0.13	0.031
Retired	−0.00	−0.67/0.67	0.997
Seasonality
Spring (Reference)
Summer	0.27	−0.27/0.81	0.332
Autumn	0.06	−0.46/0.58	0.815
Winter	0.11	−0.44/0.66	0.687

BMI: body mass index; kg/m²: kilogram per square meter; FEV₁: forced expiratory volume in one second; RV/TLC: residual volume to total lung capacity; TLco; diffusing capacity of the lung for carbon monoxide; CAT: COPD Assessment Test; PaO₂: partial pressure of oxygen in arterial blood; PaCO₂: partial pressure of carbon dioxide in arterial blood; kPa: kilopascal; CRP: c-reactive protein; 6MWD: 6-minute walk distance; 1MSTS: 1-minute sit-to-stand test. All values are adjusted for baseline handgrip strength.

Table 3. Univariate mixed effect analysis of changes in possible predictors for handgrip strength (kg) decline over time, dominant side.

	B	95% CI	p value
Change in BMI (kg/m^2)	0.08	0.01/0.16	0.034
Change in FEV1 (% pred)	−0.01	−0.03/0.01	0.197
Change RV/TLC (%)	0.02	0.00/0.04	0.014
Change RV/TLC squared* (%)	0.00	−0.00/0.00	0.282
Change in TLco (% pred.)	−0.02	−0.04/−0.00	0.016
Change TLco squared* (% pred.)	0.00	−0.00/0.00	0.065
Change in CAT (points)	0.07	0.03/0.11	<0.001
Change in CAT squared* (points)	−0.01	−0.01/−0.00	0.010
Change in PaO2 (kPa)	−0.07	−0.17/0.03	0.192
Change in PaCO2 (kPa)	0.24	−0.06/0.54	0.114
Change in CRP	−0.01	−0.02/0.01	0.554
Change in 6MWD (m)	−0.00	−0.00/0.00	0.374
Change in 1MSTS (repetitions)	−0.00	−0.04/0.03	0.862
Change in number of steps per day, N/1000	−0.00	−0.15/−0.03	0.001
Change in number of steps per day squared*, N/1000	9.67	−5.21/24.55	0.203

BMI: body mass index; kg/m²: kilogram per square meter; FEV₁: forced expiratory volume in one second; RV/TLC: residual volume to total lung capacity; TLco; diffusing capacity of the lung for carbon monoxide; CAT: COPD Assessment Test; PaO₂: partial pressure of oxygen in arterial blood; PaCO₂: partial pressure of carbon dioxide in arterial blood; kPa: kilopascal; CRP: c-reactive protein; 6MWD: 6-minute walk distance; 1MSTS: 1-minute sit-to-stand test; *: squared due to non-linearity. All values are adjusted for baseline handgrip strength.

Figure 2. Course of handgrip strength over time in relation to baseline-adjusted FEV₁ in % pred.

Table 4. Multivariate mixed effect model of possible predictors for handgrip decline (kg) over time, dominant side.

	B	95% CI	p value
BMI (kg/m^2)	−0.06	−0.13/0.00	0.052
Change in BMI (kg/m^2)	0.02	−0.06/0.10	0.604
FEV1 (% pred.)	−0.01	−0.03/0.01	0.297
Number of steps per day, N/1000	0.11	0.03/0.18	0.006
Change in CAT squared* (points)	−0.01	−0.01/−0.00	0.034

BMI: body mass index; kg/m²: kilogram per square meter; FEV₁: forced expiratory volume in one second; CAT: COPD Assessment Test; *: squared due to non-linearity. All values are adjusted for baseline handgrip strength.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.