Determining the minimally important difference in quadriceps strength in individuals with COPD using a fixed dynamometer

Figures & data

Table 1 Baseline characteristics of the patients

n	157
Male/female	93/64
Age, years	63±9
BMI, kg/m^2	26±6
Dyspnea, mM RC	2±1
Lung function
FEV1, % predicted	47±19
FVC, % predicted	79±23
FEV1/FVC, %	45±16
GOLD 1, n (%)	8 (5)
GOLD 2, n (%)	58 (37)
GOLD 3, n (%)	64 (41)
GOLD 4, n (%)	27 (17)
QMVC, Nm	96±37
6MWD, m	392±107
6MWD, % predicted	68±19
SGRQ total score	53±16
HADS
Anxiety	8±4
Depression	7±4
Total	15±7
BODE index	4±2

Notes: Data presented as mean ± SD unless otherwise indicated. Predicted values for 6MWD taken from Troosters et al.³⁵

Abbreviations: BMI, body-mass index; mMRC, modified Medical Research Council (scale); FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; QMVC, quadriceps maximal voluntary contraction; 6MWD, 6-minute walk distance; SGRQ, St George’s respiratory questionnaire; HADS, Hospital Anxiety and Depression Scale; BODE, body mass, airflow obstruction, dyspnea, and exercise.

Table 2 Changes in parameters measured at baseline and end of PRP

	Baseline	End	Change (absolute)	Change (%)
QMVC, Nm	96±37	105±40	9±16	11±19a
6MWD, m	392±107	438±102	42±50	13±17a
SGRQ total	53±16	44±16	−9±17	−13±25a
HADS
Anxiety	8±4	7±4	−2±3	−15±47a
Depression	7±4	5±4	−1±3	−14±52a
Total	15±7	12±7	−3±6	−18±38a

Notes:

a P<0.001. Data presented as mean ± SD.

Abbreviations: PRP, pulmonary rehabilitation program; QMVC, quadriceps maximal voluntary contraction; 6MWD, 6-minute walk distance; SGRQ, St George’s respiratory questionnaire; HADS, Hospital Anxiety and Depression Scale.

Figure 1 Box plot of changes in z-scores of QMVC and 6MWD from baseline to the end of the PRP.

Abbreviations: QMVC, quadriceps maximal voluntary contraction; 6MWD, 6-minute walk distance; PRP, pulmonary rehabilitation program.

Figure 2 Distribution of subjects.

Notes: (A)Subjects with changes in QMVC and 6MWD in terms of respective MIDs of 7.5 Nm and 30 m; (B) subjects with changes in QMVC and SGRQ in terms of respective MIDs of 7.5 Nm and −4 points.
Abbreviations: QMVC, quadriceps maximal voluntary contraction; 6MWD, 6-minute walk distance; MIDs, minimally important differences; SGRQ, St George’s respiratory questionnaire.

Table S1 Baseline characteristics of the patients from three centers

	Nantes		Morlaix
	University Hospital of Nantes	Tourmaline Medical Centre
n	18	20	119
Male/female	15/3	12/8	66/53
Age, years	63±7	63±10	63±9
BMI, kg/m^2	25±6	25±6	26±6
Dyspnea, mMRC	3±1	2±1	2±1*
Lung function
FEV1, % predicted	48±22	48±17	47±18
FVC, % predicted	77±21	75±22	78±24
FEV1/FVC, %	48±14	29±28	48±12
GOLD 1, n (%)	1 (6)	1 (5)	6 (5)
GOLD 2, n (%)	5 (28)	8 (40)	45 (38)
GOLD 3, n (%)	10 (56)	9 (45)	45 (38)
GOLD 4, n (%)	2 (11)	2 (10)	27 (17)
QMVC, Nm	92±25	99±30	96±40
6MWD, m	304±101	443±108‡	397±101*
6MWD, % predicted	53±17	76±20‡	69±18*
SGRQ total score	64±15	52±18	52±16*
HADS
Anxiety	9±4	8±4	8±5
Depression	7±4	6±4	7±4
Total	16±7	14±6	15±7
BODE index	5±2	4±2	3±2

Notes:

* P<0.05, significant difference between University Hospital of Nantes’ and Morlaix;

‡ P<0.05, significant difference between University Hospital of Nantes and Tourmaline Medical Centre. Data presented as mean ± SD unless otherwise indicated. Predicted values for 6MWD taken from Troosters et al.³

Abbreviations: BODE, body mass, airflow obstruction, dyspnea, and exercise; BMI, body-mass index; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; HADS, Hospital Anxiety and Depression Scale; mMRC, modified Medical Research Council (scale); QMVC, quadriceps maximal voluntary contraction; 6MWD, 6-minute walk distance; SGRQ, St George’s respiratory questionnaire.

Table S2 Comparison of the changes in parameters measured at baseline and the end of PRP in the three centers

	Nantes								Morlaix
	University Hospital of Nantes				Tourmaline Medical Centre
	Baseline	End	Change (absolute)	Change (%)	Baseline	End	Change (absolute)	Change (%)	Baseline	End	Change (absolute)	Change (%)
QMVC, Nm	92±25	108±26	16±10	19±14*	99±30	116±40	17±16	17±15*	96±40	103±42	7±16	8±20*,‡
6MWD, m	304±101	361±89	36±88	13±27	443±108	480±96	36±48	11±19*	397±101	441±100	43±43	13±14*
SGRQ total	64±15	52±20	−7±8	−12±14*	52±18	44±13	−11±21	−16±45	52±16	44±15	−8±12	−13±25*
HADS
Anxiety	9±4	6±4	−2±3	−29±33*	8±4	7±3	−2±4	−2±61	8±5	7±4	−2±3	−15±47*
Depression	7±4	6±4	0±2	18±64	6±4	7±4	0±2	2±34	7±4	5±4	−2±3	−19±51*
Total	16±7	12±7	−2±3	−18±22*	14±6	14±6	−2±6	−10±44	15±7	12±7	−3±6	−19±39*

Notes:

* P<0.05 between baseline and end of PRP;

‡ P<0.05, significant difference between Nantes and Morlaix. Data presented as mean ± SD.

Abbreviations: HADS, Hospital Anxiety and Depression Scale; 6MWD, 6-minute walk distance; PRP, pulmonary rehabilitation program; QMVC, quadriceps maximal voluntary contraction; SGRQ, St George’s respiratory questionnaire.

TroostersTGosselinkRDecramerMSix minute walking distance in healthy elderly subjectsEur Respir J199914227027410515400

 PubMed Web of Science ®Google Scholar

TroostersTGosselinkRDecramerMSix minute walking distance in healthy elderly subjectsEur Respir J199914227027410515400

 PubMed Web of Science ®Google Scholar