Physical activity levels in asthma: relationship with disease severity, body mass index and novel accelerometer-derived metrics

Figures & data

Table 1. Baseline characteristics of groups.

	MHW Mild-moderate, asthma healthy weight, n = 25	MOW Mild-moderate, asthma overweight, n = 25	DOW Difficult asthma, overweight, n = 25	P value
Age, years	38 (27-62)	62 (54-67)	57 (48-63)	<0.001
Age at diagnosis	23 (±20)	34 (±22)	31 (±19)	0.135
Disease duration, years	18 (8-28)	29 (8-42)	24 (15-37)	0.160
Gender: Female	17 (68)	12 (48)	13 (52)	0.321
Smoking Status: Never smoker	20 (80)	16 (64)	12 (48)	0.622
Current smoker	2 (8)	0 (0)	3 (12)
Ex-smoker	3 (12)	9 (36)	10 (40)
Pack years	5 (3 − 24)	15 (2 − 23)	22 (9 − 28)	0.186
Atopy	4 (16)	3 (12)	16 (64)	<0.001
Allergic rhinitis	18 (72)	14 (56)	22 (88)	0.042
Perennial rhinitis	10 (40)	5 (20)	15 (60)	0.016
Nasal polyps*	1 (4)	4 (16)	5 (20)	0.228
Eczema	9 (36)	5 (20)	7 (28)	0.452
GORD	4 (16)	13 (52)	22 (88)	<0.001
DFB/VCD*	0 (0)	1 (4)	8 (32)	0.001
Anxiety or depression	6 (24)	6 (24)	16 (64)	0.003
Emphysema*	0 (0)	0 (0)	1 (4)	0.368
Bronchiectasis*	0 (0)	4 (4)	3 (12)	0.161
SAFS/ABPA*	0 (0)	0 (0)	8 (32)	<0.001
Diabetes mellitus*	0 (0)	1 (4)	6 (24)	0.008
Hypertension*	0 (0)	7 (28)	3 (12)	0.015
Cardiac disease*	1 (4)	0 (0)	7 (28)	0.003
Osteopenia/osteoporosis*	1 (4)	1 (4)	13 (52)	<0.001
SABA inhaled*	24 (96)	24 (96)	25 (100)	0.602
SABA nebs*	0 (0)	0 (0)	14 (56)	<0.001
LAMA*	0 (0)	0 (0)	23 (92)	<0.001
ICS alone	10 (40)	12 (48)	0 (0)	<0.001
ICS/LABA	10 (40)	13 (52)	25 (100)	<0.001
BDP equivalent, mcg, mean (95% CI)	420 (280-560)	536 (418-653)	1904 (1729-2079)	<0.001
Prednisolone maintenance*	0 (0)	0 (0)	12 (48)	<0.001
Prednisolone maintenance dose, mg	0	0	6 (4 to 8)	<0.001
Montelukast	2 (8)	0 (0)	18 (72)	<0.001
Theophylline*	0 (0)	1 (4)	12 (48)	<0.001
Azithromycin*	0 (0)	0 (0)	4 (16)	0.016
Omalizumab*	0 (0)	0 (0)	6 (24)	0.002
Mepolizumab*	0 (0)	0 (0)	2 (8)	0.130
Nasal steroid	4 (16)	4 (16)	12 (48)	0.013
PPI/H2A	3 (12)	7 (28)	20 (80)	<0.001
In 1 year: Prednisolone boosts	0 (0 − 1)	0 (0 − 0)	3 (2 − 5)	<0.001
In 1 year: GP attendances	0 (0 − 1)	0 (0 − 0)	1 (0 − 3)	0.005
In 1 year: A & E attendances	0 (0 − 0)	0 (0 − 0)	0 (0 − 1)	0.007
In 1 year: Hospital admissions	0 (0 − 0)	0 (0 − 0)	0 (0 − 1)	<0.001
In 1 year: ICU admissions	0 (0 − 0)	0 (0 − 0)	0 (0 − 0)	0.132
BMI, kg/m2	23.2 (21.7 − 24)	29 (27 − 32)	36.2 (33 − 40.3)	<0.001
MRC dyspnea scale	1 (1 − 1)	1 (1 − 1)	2 (2 − 3.5)	<0.001
ACQ6	0.5 (0 − 0.8)	0.3 (0.2 − 0.7)	2.8 (1.85 − 3.3)	<0.001
AQLQ: Overall	6.2 (5.7 − 6.7)	6.5 (5.6 − 6.8)	4 (3.1 − 5.1)	<0.001
AQLQ: Symptom domain	6.2 (5.8 − 6.7)	6.4 (6.1 − 6.8)	4.1 (3.2 − 5)	<0.001
AQLQ: Activity domain	6.3 (5.8 − 6.9)	6.3 (5.2 − 6.8)	3.8 (3.2 − 4.6)	<0.001
AQLQ: Emotional domain	6.6 (5.9 − 7)	6.6 (5.9 − 7)	4.6 (3.2 − 5.6)	<0.001
AQLQ: Environmental domain	5.8 (5.3 − 6.7)	6.5 (5.5 − 7)	4.5 (2.3 − 5.4)	<0.001
HAD: Anxiety score	3 (1.5 − 7)	5 (2.5 − 7.5)	7 (4 − 13)	0.021
HAD: Depression score	1 (0 − 2)	2 (1 − 3.5)	8 (6 − 11)	<0.001
Eosinophils (x10^9/L)	0.2 (0.1 − 0.3)	0.1 (0.1 − 0.2)	0.3 (0.1 − 0.4)	0.203
FeNO, ppb	22 (15 − 29)	20 (18 − 25)	39 (16 − 71)	0.185
PEF, L/min	487 (436 − 543)	478 (402 − 576)	398 (314 − 485)	0.011
pre-BD FEV1, % pred.- mean (95% CI)	95.1 (90 − 100)	93.8 (88 − 100)	66.4 (59 − 74)	<0.001
pre-BD FEV1/FVC % - mean (95% CI)	73.7 (69-78)	71.4 (68-75)	65.4 (62-69)	0.007
% change in FEV1 post-BD	3.5 (0.5 to 5.5)	4.8 (-0.4 to 5.9)	3.3 (-1.0 to 13)	0.744
Best 6MWD, m	574 (528- 619)	517 (483- 550)	322 (268-376)	<0.001
Borg score post 6MWT	0 (0 to 1)	0 (0 to 1)	3 (1 to 3)	<0.001

Data expressed as mean ± SD, median (IQR) or number and proportion unless otherwise specified.

* p values calculated using Kruskall-Wallis, remaining proportions p values calculated using Chi-square test.

Abbreviations used in table: GORD gastro-oesophageal reflux disease, DFB dysfunctional breathing, VCD vocal cord dysfunction, SAFS- severe asthma with fungal sensitization, ABPA allergic bronchopulmonary aspergillosis, SABA short acting beta-2 agonist, LAMA- long acting muscarinic antagonist, ICS inhaled corticosteroid, LABA long acting beta-2 agonist, BDP beclometasone diproprionate dose equivalent, mcg micrograms, mg milligrams, PPI proton pump inhibitor, H2A H2 receptor antagonist, OOH out of hours, A&E accident and emergency department, GP General Practitioner, ICU intensive care unit, BMI body mass index, MRC Medical Research Council dyspnea score, ACQ6 Asthma Control Questionnaire 6, AQLQ Asthma Quality of Life Questionnaire, HAD Hospital Anxiety and Depression scale, FeNO fraction of exhaled nitric oxide, PEFR peak expiratory flow rate, pre-BD pre-bronchodilator, FEV1 forced expiratory volume in 1 s, pred.- predicted, FVC forced vital capacity, post-BD post bronchodilator, 6MWT 6 min walk test.

Figure 1. Time spent in activity thresholds. Bar chart showing mean and 95% confidence intervals for inactive time, light and moderate-vigorous physical activity across the three groups. Annotations display p values between groups when Tukey’s multiple comparisons tests are performed.

Figure 2. Average acceleration and intensity gradient results. Bar charts showing a) average acceleration and b) intensity gradient across the three groups. Annotations display p values between groups when multiple comparisons testing is performed using Dunn’s multiple comparison tests.

Table 2. Accelerometer results.

	MHW (mild-moderate healthy weight)	MOW (mild-moderate overweight)	DOW (Difficult-to-control overweight)	P value	Between group comparisons p values
					MHW/MOW	MOW/DOW	MHW/DOW
Inactive time (min.d^-1) mean (95% CI)	1079 (1037 − 1122)	1128 (1094 to 1161)	1202 (1170 − 1234)	<0.001	<0.212	<0.008	<0.001
LPA (min.d^-1) mean (95% CI)	259 (228 − 289)	237 (212 − 263)	196 (171 − 222)	0.007	<0.653	<0.033	<0.003
MVPA (min.d^-1) mean (95% CI)	103 (80 − 127)	79 (58 − 99)	42 (33 − 52)	<0.001	<0.128	<0.027	<0.001
Intensity gradient, median (IQR)	−2.63 (-2.97 to −2.33)	−2.62 (-2.74 to −2.55)	−2.85 (-2.96 to −2.73)	<0.001	>0.999	<0.005	<0.001
Average acceleration (mg) median (IQR)	27.8 (21.7 − 31.0)	24.4 (20.4 − 27.5)	17.1 (13.7 − 20.5)	<0.001	<0.486	<0.004	<0.001

Abbreviations used in table: MVPA moderate to vigorous physical activity, LPA light physical activity. Units min.d ^{− 1 min} per day, mg.d milligravitational units per day.

Data expressed as mean and 95% confidence intervals for inactive time, LPA and MVPA; or median and IQR for intensity gradient and average acceleration.

Table 3. Correlations of PA parameters and relevant asthma measures.

	Inactive time		LPA		MVPA		Intensity Gradient		Average Acceleration
Variable	r	p	r	p	r	p	r	p	r	p
BDP dose	0.476	<0.001	-0.343	0.009	-0.548	<0.001	-0.507	<0.001	-0.591	<0.001
Prednisolone maintenance dose	0.171	0.205	−0.103	0.445	−0.202	0.131	-0.221	0.009	-0.273	0.040
Prednisolone boosts per year	0.346	0.009	-0.262	0.049	-0.435	<0.001	-0.47	<0.001	-0.475	<0.001
Annual GP visits	0.025	0.855	-0.043	0.752	-0.103	0.444	-0.196	0.144	-0.118	0.381
Annual A&E visits	0.157	0.244	−0.192	0.153	−0.161	0.232	-0.267	0.045	−0.212	0.098
BMI (kg/m^2)	0.507	<0.001	-0.410	0.002	-0.484	0.001	-0.402	0.002	-0.573	<0.001
ACQ6	0.427	0.001	-0.368	0.005	-0.423	0.001	-0.367	0.005	-0.463	<0.001
Overall AQLQ	-0.462	<0.001	0.438	<0.001	0.448	<0.001	0.442	<0.001	0.531	<0.001
AQLQ symptoms	-0.375	0.004	0.336	0.011	0.386	0.003	0.409	0.002	0.451	<0.001
AQLQ activity	-0.529	<0.001	0.498	<0.001	0.493	<0.001	0.452	<0.001	0.580	<0.001
AQLQ emotional	-0.422	0.001	0.385	0.003	0.441	<0.001	0.427	<0.001	0.501	<0.001
AQLQ environmental	−0.188	0.161	0.215	0.108	0.190	0.157	0.283	0.033	0.262	0.049
HADS anxiety	−0.032	0.811	−0.097	0.473	0.136	0.315	0.182	0.175	0.138	0.307
HADS depression	−0.248	0.064	0.174	0.195	0.276	0.038	0.307	0.020	0.321	0.015
Eosinophil count (x 10^9/L)	0.179	0.187	−0.152	0.264	−0.174	0.199	−0.153	0.260	−0.235	0.082
FeNO (ppb)	0.334	0.014	−0.266	0.052	-0.375	0.005	−0.151	0.276	-0.301	0.027
Pre-BD FEV1 % predicted	-0.495	<0.001	0.476	<0.001	0.441	0.001	0.544	<0.001	0.560	<0.001
6MWD (m)	-0.569	<0.001	0.394	0.002	0.680	<0.001	0.690	<0.001	0.719	<0.001
Borg score post 6MWT	0.423	0.001	-0.399	0.002	-0.396	0.0023	-0.280	<0.001	-0.434	<0.001

Significant p values and corresponding correlation co-efficients highlighted in bold.

Abbreviations used in table: LPA- light physical activity, MVPA- moderate-vigorous physical activity, BDP- beclometasone diproprionate equivalent dose of inhaled corticosteroid, GP- general practitioner, A&E- accident and emergency, BMI- body mass index, ACQ6- 6 point asthma control questionnaire, AQLQ- asthma quality of life questionnaire, HAD- hospital anxiety and depression score, FeNO- fraction of exhaled nitric oxide, pre-BD- pre-bronchodilator, FEV1- forced expiratory volume in 1 s, 6MWD- six-minute walk distance, 6MWT- six-minute walk test.

Table 4. Comparison of highest and lowest quartiles based on average acceleration.

Parameter	Highest AA quartile	Lowest AA quartile	P value
Age (years)	47.4 (15.7)	58.4 (10.7)	0.041
BDP equivalent dose (mcg)	479 (345)	1179 (569)	<0.001
Annual prednisolone boosts	0 (0-0.3)	2 (0.8-5.5)	<0.001
Annual GP visits	0 (0-0.25)	0 (0-3)	0.133
Annual A&E Visits	0 (0)	0 (0-1)	0.115
BMI (kg/m^2)	24.3 (2.3)	37.5 (7.3)	<0.001
MRC Dyspnea score	1 (1-1)	3 (2-3.25)	<0.001
ACQ6	0.5 (0.4)	2.4 (1.3)	<0.001
AQLQ overall	6.3 (0.6)	4.2 (1.6)	<0.001
AQLQ symptoms	6.5 (6.1-6.8)	4.0 (2.9-5.9)	0.001
AQLQ activity	6.6 (5.9-6.9)	3.5 (2.7-5.1)	<0.001
AQLQ emotional	6.8 (6.6-7)	4.1 (2.9-5.7)	<0.001
AQLQ environmental	6.4 (5.7-7.0)	5 (2.2-6.5)	0.084
HADS anxiety	5.9 (3.0)	8.3 (4.7)	0.116
HADS depression	2 (0-6)	8.5 (3.8-10.5)	<0.001
Eosinophils (x10^9/L)	0.2 (0.1-0.2)	0.3 (0.1-0.4)	0.328
FeNO (parts per billion)	23 (16-44)	42 (19-64)	0.346
Pre-BD FEV1 % predicted	94.9 (12.4)	64 (19.0)	<0.001
Pre-BD FEV1/FVC ratio	70.6 (9.4)	65.0 (9.7)	0.138
6MWD (metres)	556 (66)	289 (127)	<0.001
Borg Score	0 (0-1)	3 (1-3)	0.003

Results are expressed as mean (SD) and median (IQR). Significant p values are highlighted in bold.

Abbreviations used in table: BDP- beclometasone diproprionate equivalent dose of inhaled corticosteroid, GP- general practitioner, A&E- accident and emergency, BMI- body mass index, MRC Medical Research Council, ACQ6 6-point asthma control questionnaire, AQLQ- asthma quality of life questionnaire, HAD- hospital anxiety and depression score, FeNO- fraction of exhaled nitric oxide, pre-BD- pre-bronchodilator, FEV1- forced expiratory volume in 1 s, FEV1/FVC ratio forced expiratory volume in 1 s/forced vital capacity, 6MWD- six-minute walk distance.

Table 5. Simple linear regression results.

Dependent variable	Independent variable	p value	β coefficient	R2
ACQ6	Inactive time	<0.001	0.007	0.227
	LPA	<0.001	−0.010	0.194
	MVPA	0.003	−0.01	0.150
	IG	0.008	−1.63	0.121
	AA	0.001	−0.061	0.175
AQLQ	Inactive time	<0.001	−0.008	0.239
	LPA	<0.001	0.010	0.197
	MVPA	0.002	0.013	0.162
	IG	0.002	1.998	0.168
	AA	<0.001	0.068	0.199

Significant p values are highlighted in bold. Abbreviations used in table: ACQ6- 6-point asthma control questionnaire, LPA- light physical activity, MVPA- moderate-vigorous physical activity, IG- intensity gradient, AA- average acceleration, AQLQ- asthma quality of life questionnaire.

Table 6. Multiple linear regression results. ACQ and AQLQ as dependent variables with PA parameter plus BMI, age and gender as independent variables.

Dependent variable	Model p value	Independent PA parameter	β co-efficient	β co-efficient p value	R^2
ACQ	<0.001	Inactive time	0.004	0.038	0.445
	<0.001	LPA	−0.004	0.159	0.419
	<0.001	MVPA	−0.010	0.011	0.469
	<0.001	IG	−1.383	0.019	0.458
	<0.001	AA	−0.043	0.026	0.452
AQLQ	<0.001	Inactive time	−0.005	0.016	0.464
	<0.001	LPA	0.005	0.095	0.431
	<0.001	MVPA	0.012	0.005	0.486
	<0.001	IG	1.885	0.002	0.505
	<0.001	AA	0.054	0.007	0.480

Significant p values are highlighted in bold. Abbreviations used in table: ACQ6- 6 point asthma control questionnaire, LPA- light physical activity, MVPA- moderate-vigorous physical activity, IG- intensity gradient, AA- average acceleration, AQLQ- asthma quality of life questionnaire.