Progression of physical inactivity in COPD patients: the effect of time and climate conditions – a multicenter prospective cohort study

Figures & data

Table 1 Baseline characteristics of patients who completed follow up and separated by center

Variable	Total population (N=157)	Athens (N1=37)	Edinburgh (N2=25)	Leuven (N3=45)	London (N4=30)	Groningen (N5=20)	p-value
Recruitment site	Hospital/rehabilitation/primary care	Hospital	Hospital	Rehabilitation	Hospital	Primary care	NA
Age (years)	67.2±7.8	66.2±8.3	71±7.1	66.4±6.3	68.8±8.4	63.8±8.9	0.019
Male/female	119:38	27:10	20:5	36:9	21:9	15:5	0.846
BMI (kg/m^2)	26.7±4.9	26.7±6.1	27.3±4.3	27.1±4.7	25.5±5	26.8±3.3	0.684
FEV1%	57.7±21.9	48.3±15.5	61.6±24.2	64.6±22	54±25.2	60.1±18.4	0.009
RV/TLC%	50.2±11.9	50.9±13.6	47.9±9.5	50.3±13	52.5±9.3	47.8±11.7	0.576
6MWD (m)	449.1±124.1	381.5±73.2	424.6±119.2	502±142.7	440.5±120.3	497.7±100.6	<0.001
QMVC (kg)	33.4±32.4	27.9±7.8	41±11.1	35.1±10	30.6±9.5	34.2±15.9	<0.001
AG steps	4284 (3533)	3807 (3585)	3338 (2615)	5166 (4216)	4207 (3552)	3784 (3710)	0.238
AG mvpa	8.8 (18.8)	7.8 (18.8)	7.2 (11.4)	9.9 (20.6)	12.1 (29.3)	7.5 (10.7)	0.663
AG VMU	374902.4 (265269)	309289.1 (194928)	322229.6 (161516)	453780 (238837)	356768.9 (284389)	385016.8 (228490)	0.178
MM steps	4690 (3708)	4135 (3486)	4070 (2554)	5774 (4418)	3583 (3600)	4733 (4231)	0.005
MM walktime (mins)	59.1 (34.9)	54.3 (40.7)	52 (19.2)	75.6 (42)	48 (43.5)	57.1 (47.7)	0.003
MM intensity (g)	0.2 (0)	0.2 (0)	0.2 (0)	0.2 (0)	0.2 (0)	0.2 (0)	0.080
MM VMU	286039.6 (237721)	234813.2 (245045)	215748 (122400)	364976.9 (331440)	297922.1 (230476)	332468.7 (270081)	0.057
Temp (°C)	17.1 (7.5)	20.7 (14)	14.9 (4.8)	16.1 (6.9)	19.4 (7.2)	12.9 (5)	<0.001
Sunshine (hrs)	4.7 (3.5)	6.5 (4)	2.6 (1.5)	-	4.3 (2.7)	-	<0.001
Rainfall (hrs/day)	0.2 (1.2)	0 (0)	1.4 (1.9)	0.3 (1.3)	0.3 (1)	0.1 (0.9)	<0.001
Day length (mins)	640.2 (158.4)	662.3 (117.5)	647.2 (191.6)	647.4 (259)	694.1 (211)	589.3 (80.8)	<0.001
HAD A^$	5 (7)	6 (7)	6 (4.5)	4.5 (6.8)	5 (6.3)	3 (4.8)	0.265
HAD D^$	4 (5)	5 (4.5)	35 (4.5)	4 (5.8)	4 (4.5)	2.5 (5.5)	0.176
CAT^$	13 (10.5)	14 (8.5)	12 (9)	14 (18)	11 (16)	10.5 (9.5)	0.832
CCQ^$	1.7 (1.6)	1.6 (1.4)	1.6 (1.6)	1.4 (1.2)	2.1 (2.2)	1.2 (1.9)	0.473

Note: ~Male/female represented as frequencies with the result of Chi-squared test presented. ^$Although these data are presented, there were several missing values so they were not used in further analysis.

Abbreviations: BMI, body mass index; RV/TLC%, ratio of residual volume to total lung volume percentage predicted; QMVC, quadriceps maximal voluntary contraction; AG, Actigraph GT3X monitor; MM, Dynaport MiniMod monitor; mvpa, moderate to vigorous physical activity; VMU, vector magnitude units; ln, natural logarithm; °C, degrees centigrade; HAD A, Hospital Anxiety and Depression Scale, Anxiety score; HAD D, Hospital Anxiety and Depression Scale, Depression score; CAT, COPD Assessment Tool; CCQ, Clinical COPD Questionnaire.

Figure 1 Study flowchart.

Table 2 Change of physical activity measures and 6MWD with time for patients who completed follow-up, in univariate analysis

Variable	Baseline	6 months	12 months	p-Value^
FEV1 (% predicted)	57.7±21.9	57.2±22.6	57.8±22.2	0.983
6MWD (m)	449.8±127.2	430.8±132.3	440.5±131.8	0.839
AG steps	4284 (3533)	3594 (3212)	3533 (2930)	<0.001
AG mvpa	8.8 (18.8)	7.4 (17.4)	6.1 (15.7)	<0.001
AG VMU	374,902.4 (265,269)	330,420 (223,152)	336,240 (214,432)	<0.001
MM steps	4690 (3708)	4264 (3378)	4359 (3425)	0.001
MM walktime (mins)	59.1 (34.9)	53.2 (34.4)	56.9 (38.7)	0.001
MM intensity (g)	0.183 (0)	0.183 (0)	0.181 (0)	<0.001
MM VMU	286,039.6 (237,721)	265,253.2 (218,109)	259,447.4 (199,472)	<0.001

Note: ^p-Value for comparisons between baseline and 12-month follow-up.

Abbreviations: AG, Actigraph GT3X monitor; mvpa, moderate to vigorous physical activity; MM, Dynaport MiniMod monitor; VMU, vector magnitude units.

Table 3 Estimated coefficients and corresponding confidence intervals of GLM regressors, calculated for each physical activity parameter recorded by Dynaport MiniMod monitor

PA measures	Predictor	B	Std error	95% CI	p-value
AG steps	Visit
	-baseline	0.156	0.057	0.045–0.267	0.006
	-6 months follow-up	0.056	0.074	-0.088–0.201	0.446
	-12months follow-up	Reference group	Reference group	Reference group	Reference group
	Center
	-Athens	0.172	0.336	-0.031–0.375	0.097
	-Edinburgh	-0.229	0.104	-0.454	0.048
	-Leuven	-0.067	0.077	-0.218–0.084	0.387
	-London	-0.066	0.086	-0.233–0.102	0.443
	-Groningen	Reference group	Reference group	Reference group	Reference group
	Age	-0.014	0.003	-0.012	<0.001
	FEV1% predicted	0.007	0.001	0.005–0.010	<0.001
	RV/TLC% predicted	0.003	0.002	-3E-4–0.007	0.095
	QMVC	-1.00E-4	0.002	-0.004–0.005	0.964
	6MWD	0.003	2.00E-04	0.002–0.003	<0.001
	Temperature	0.009	0.006	0.003–0.031	0.132
	Daylength (hrs)
	-<7.8	0.107	0.352	-1.378	0.761
	-20.2	-0.002	0.073	-0.285	0.977
	->12.4	Reference group	Reference group	Reference group	Reference group
	Rainfall (mm/day)
	-<1.7	-0.205	0.102	-0.401	0.046
	-4.3	-0.291	0.124	-0.487	0.019
	->2.6	Reference group	Reference group	Reference group	Reference group
AGmvpa	Visit
	-baseline	0.475	0.141	0.197–0.752	0.001
	-6 months follow-up	0.021	0.168	-0.307–0.350	0.898
	-12 months follow-up	Reference group	Reference group	Reference group	Reference group
	Centre
	-Athens	1.542	0.261	1.031–2.053	<0.001
	-Edinburgh	0.455	0.288	-0.110–1.020	0.114
	-Leuven	0.937	0.18	0.584–1.291	<0.001
	-London	0.874	0.2	0.477–1.272	<0.001
	-Groningen	Reference group	Reference group	Reference group	Reference group
	Age	-0.048	0.007	-0.029	<0.001
	FEV1% predicted	0.008	0.003	0.003–0.014	0.003
	RV/TLC% predicted	-0.001	0.004	-0.009–0.007	0.847
	QMVC	-0.004	0.006	-0.016–0.009	0.535
	6MWD	0.004	0.001	0.003–0.005	<0.001
	Temperature	-0.038	0.014	-0.056	0.007
	Daylength (hrs)
	-<7.8	-0.938	0.809	-3.172	0.246
	-20.2	-0.282	0.158	-0.62	0.075
	->12.4	Reference group	Reference group	Reference group	Reference group
	Rainfall (hrs/day)
	-<1.7	0.009	0.237	-0.93	0.97
	-4.3	-0.178	0.297	-1.164	0.549
	->2.6	Reference group	Reference group	Reference group	Reference group
AGVMU	Visit
	-baseline	0.156	0.046	0.064–0.246	0.001
	-6 months follow-up	0.057	0.06	-0.059–0.174	0.335
	-12 months follow-up	Reference group	Reference group	Reference group	Reference group
	Center
	-Athens	0.022	0.083	-0.141–0.184	0.795
	-Edinburgh	-0.052	0.094	-0.237–0.133	0.581
	-Leuven	-0.026	0.062	-0.148–0.097	0.68
	-London	-0.058	0.069	-0.193–0.076	0.394
	-Groningen	Reference group	Reference group	Reference group	Reference group
	Age	-0.012	0.003	-0.01	<0.001
	FEV1% predicted	0.006	0.001	0.004–0.008	<0.001
	RV/TLC% predicted	0.001	0.002	-0.002–0.004	0.364
	QMVC	-0.003	0.002	-0.007–0.001	0.154
	6MWD	0.002	2.00E-04	0.001–0.002	<0.001
	Temperature	0.007	0.005	-0.002–0.017	0.119
	Daylength (hrs)
	-<7.8	-0.138	0.287	-1.124	0.631
	-20.2	0.002	0.059	-0.229	0.967
	->12.4	Reference group	Reference group	Reference group	Reference group
	Rainfall (hrs/day)
	-<1.7	-0.163	0.084	-0.329	0.051
	-4.3	-0.186	0.101	-0.397	0.067
	->2.6	Reference group	Reference group	Reference group	Reference group

Abbreviations: RV/TLC%, ratio of residual volume to total lung volume percentage predicted; GLM, generalized linear model; PA, physical activity; Std, standard; AG, Actigraph GT3X monitor; RV, residual volume; TLC, total lung capacity; QMVC, quadriceps maximal voluntary contraction; mvpa, moderate to vigorous physical activity; VMU, vector magnitude units; E-4, 10⁻⁴.

Table 4 Estimated coefficients and corresponding confidence intervals of GLM regressors, calculated for each physical activity parameter recorded by Dynaport MiniMod monitor

PA measures	Predictor	B coefficients	Std error	95% CI	p-value
MM steps	Visit
	-baseline	0.029	0.059	0.086–0.145	0.033
	-6 months follow-up	-0.08	0.077	-0.232–0.072	0.301
	-12 months follow-up	Reference group	Reference group	Reference group	Reference group
	Center
	-Athens	0.127	0.107	-0.081–0.336	0.232
	-Edinburgh	-0.237	0.124	-0.479–0.005	0.055
	-Leuven	-0.054	0.081	-0.212–0.104	0.503
	-London	-0.156	0.093	-0.337–0.026	0.093
	-Groningen	Reference group	Reference group	Reference group	Reference group
	Age	-0.006	0.003	-0.013–4.4E-5	0.048
	FEV1% predicted	0.006	0.001	0.004–0.009	<0.001
	RV/TLC% predicted	0.003	0.002	-0.001–0.007	0.11
	QMVC	-2.10E-4	0.003	-0.005–0.005	0.932
	6MWD	0.003	3.00E-4	0.002–0.003	<0.001
	Temperature	0.006	0.006	-0.006–0.018	0.313
	Daylength (hrs)
	-<7.8	-0.051	0.354	-0.746–0.643	0.885
	-20.2	-0.091	0.076	-0.240–0.058	0.23
	->12.4	Reference group	Reference group	Reference group	Reference group
	Rainfall (hrs/day)
	-<1.7	-0.258	0.105	-0.412	0.014
	-4.3	-0.354	0.128	-0.5	0.006
	->2.6	Reference group	Reference group	Reference group	Reference group
MM walktime	Visit
	-baseline	0.026	0.055	-0.081–0.133	0.632
	-6 months follow-up	-0.09	0.072	-0.231–0.051	0.21
	-12 months follow-up	Reference group	Reference group	Reference group	Reference group
	Center
	-Athens	0.107	0.099	-0.440–0.011	0.278
	-Edinburgh	-0.214	0.115	-0.188–0.104	0.062
	-Leuven	-0.042	0.075	-0.334	0.57
	-London	-0.169	0.085	-0.082–0.133	0.048
	-Groningen	Reference group	Reference group	Reference group	Reference group
	Age	-0.005	0.003	-0.0109	0.048
	FEV1% predicted	0.005	0.001	0.003–0.008	<0.001
	RV/TLC% predicted	0.003	0.002	-0.001–0.006	0.147
	QMVC	0.002	0.002	-0.003–0.067	0.396
	6MWD	0.002	2.00E-4	0.002–0.003	<0.001
	Temperature	0.006	0.006	-0.005–0.016	0.312
	Daylength (hrs)
	-<7.8	-0.027	0.328	-0.669–0.615	0.934
	-20.2	-0.098	0.07	-0.235–0.040	0.165
	->12.4	Reference group	Reference group	Reference group	Reference group
	Rainfall (hrs/day)
	-<1.7	-0.227	0.097	-0.382	0.02
	-4.3	-0.309	0.118	-0.462	0.009
	->2.6	Reference group	Reference group	Reference group	Reference group
MM intensity	Visit
	-baseline	0.015	0.015	-0.015–0.045	0.333
	-6 months follow-up	0.009	0.02	-0.030–0.048	0.648
	-12 months follow-up	Reference group	Reference group	Reference group	Reference group
	Center
	-Athens	0.043	0.027	-0.011–0.097	0.118
	-Edinburgh	0.035	0.033	-0.028–0.099	0.279
	-Leuven	-0.027	0.021	-0.067–0.014	0.198
	-London	0.081	0.024	0.035–0.127	0.001
	-Groningen	Reference group	Reference group	Reference group	Reference group
	Age	-0.006	8.00E-4	-0.003	<0.001
	FEV1% predicted	0.002	3.00E-4	0.001–0.002	<0.001
	RV/TLC% predicted	-3.50E-4	5.00E-4	-0.001–0.001	0.476
	QMVC	-0.001	6.00E-4	-0.002914	0.036
	6MWD	4.80E-4	6.50E-5	3.6E-4–0.001	<0.001
	Temperature	-7.50E-5	0.002	-0.003–0.003	0.961
	Daylength (hrs)
	-<7.8	0.043	0.092	-0.137–0.222	0.642
	-20.2	-0.004	0.019	-0.042–0.033	0.817
	->12.4	Reference group	Reference group	Reference group	Reference group
	Rainfall (hrs/day)
	-<1.7	-0.012	0.027	-0.065–0.042	0.668
	-4.3	-0.035	0.033	-0.100–0.029	0.284
	->2.6	Reference group	Reference group	Reference group	Reference group
MMVMU	Visit
	-baseline	0.085	0.056	0.024–0.194	0.026
	-6 months follow-up	-0.01	0.072	-0.152–0.131	0.885
	-12 months follow-up	Reference group	Reference group	Reference group	Reference group
	Center
	-Athens	0.129	0.1	-0.067–0.325	0.197
	-Edinburgh	-0.065	0.116	-0.293–0.163	0.576
	-Leuven	-0.114	0.076	-0.263–0.035	0.133
	-London	0.002	0.087	-0.168–0.172	0.983
	-Groningen	Reference group	Reference group	Reference group	Reference group
	Age	-0.016	0.003	-0.012	<0.001
	FEV1% predicted	0.008	0.001	0.005–0.010	<0.001
	RV/TLC% predicted	0.001	0.002	-0.003–0.004	0.699
	QMVC	-0.005	0.002	-0.00951	0.03
	6MWD	0.003	2.00E-4	0.002–0.003	<0.001
	Temperature	0.001	0.006	-0.010–0.012	0.83
	Daylength (hrs)
	-<7.8	-0.258	0.332	-0.909–0.394	0.438
	-20.2	-0.066	0.07	-0.203–0.070	0.342
	->12.4	Reference group	Reference group	Reference group	Reference group
	Rainfall (hrs/day)
	-<1.7	-0.238	0.098	-0.388	0.016
	-4.3	-0.339	0.119	-0.468	0.005
	->2.6	Reference group	Reference group	Reference group	Reference group

Abbreviations: QMVC, quadriceps maximal voluntary contraction; RV/TLC%, ratio of residual volume to total lung volume percentage predicted; E-4, 10⁻⁴; Ε-5, 10⁻⁵.