Differences in physical activity according to mMRC grade in patients with COPD

Figures & data

Table 1 Characteristics of patients

Characteristics	Total	mMRC 0	mMRC 1	mMRC 2	mMRC 3	mMRC 4
Sex (male/female), n	92/6	21/3	34/2	19/1	14/0	4/0
Age (years)	71.4±6.9	68.3±6.8	72.1±6.5	71.5±7.9	73.7±5.8	72.5±9.9
Smoking history (never/ex/current), n	0/84/14	0/19/5	0/31/5	0/20/0	0/10/4	0/4/0
GOLD stage (1/2/3/4), n	14/50/22/12	7/15/1/1	5/24/5/2	1/9/7/3	1/2/8/3	0/0/1/3
Medication
LAMA, n (%)	68 (69.4)	10 (41.7)	24 (66.7)	17 (85.0)	14 (100.0)	3 (75.0)
LABA, n (%)	34 (34.7)	2 (8.3)	12 (33.3)	10 (50.0)	7 (50.0)	3 (75.0)
ICS/LABA, n (%)	28 (28.6)	7 (29.2)	6 (16.7)	8 (40.0)	6 (42.9)	1 (25.0)
Pulmonary function
FVC (L)	3.28±0.72	3.42±0.80	3.40±0.57	3.29±0.77	2.96±0.44	2.60±0.49
FEV1 (L)	1.56±0.59	1.98±0.58	1.67±0.49	1.35±0.49	1.15±0.36	0.72±0.09
FEV1/FVC (%)	47.1±13.4	55.6±10.3	46.7±12.5	38.7±9.7	36.5±11.2	28.1±2.7
FEV1% predicted (%)	57.9±20.3	68.6±16.9	62.1±18.8	48.1±15.6	41.8±15.7	29.1±4.6

Notes: Data are presented as mean ± SD. mMRC measures are as follows; mMRC 0, I only get breathless with strenuous exercise; mMRC 1, I get short of breath when hurrying on the level or walking up a slight hill; mMRC 2, I walk slower than people of the same age on the level because of breathlessness, or I have to stop for breath when walking on my own pace on the level; mMRC 3, I stop for breath after walking about 100 meters or after a few minutes on the level; mMRC 4, I am too breathless to leave the house or I am breathless when dressing or undressing.

Abbreviations: mMRC, modified Medical Research Council; GOLD, Global Initiative for Chronic Obstructive Lung Disease; LAMA, long-acting muscarinic antagonist; LABA, long-acting β2 agonist; ICS, inhaled corticosteroid; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; SD, standard deviation.

Figure 1 Differences in PA duration according to the mMRC grade.

Notes: Kruskal–Wallis test and post hoc Dunn’s multiple comparison test were used for the comparison of PA durations according to the mMRC grade. Data are shown as a box plot (lower and upper extreme of the box represent the 25th and the 75th percentiles, respectively, and the central line represents the median). The lower and upper vertical lines represent the 5th and 95th percentiles, respectively. ^#P<0.05 versus mMRC grade 1. A: PA at ≥2 METs; B: PA at ≥22.5 METs; C: PA at ≥23 METs; D: PA at ≥23.5 METs.
Abbreviations: PA, physical activity; mMRC, modified Medical Research Council; METs, metabolic equivalents; min, minutes.

Figure 2 Differences in PAL at ≥3 METs according to the mMRC grade.

Notes: Kruskal–Wallis test and post hoc Dunn’s multiple comparison test were used for the comparison of PA durations according to the mMRC grade. Data are shown as a box plot (lower and upper extreme of the box represent the 25th and the 75th percentiles, respectively, and the central line represents the median). The lower and upper vertical lines represent the 5th and 95th percentiles, respectively.
Abbreviations: PAL, physical activity level; mMRC, modified Medical Research Council; PA, physical activity; METs, metabolic equivalents; h, hour.

Figure 3 mMRC grade and the proportion of patients with low PAL.

Notes: Chi-square test was used for comparison between mMRC grades and the proportion of patients with low PAL. *P<0.05 versus mMRC grade 0, ^#P<0.05 versus mMRC grade 1.
Abbreviations: mMRC, modified Medical Research Council; PAL, physical activity level.

Figure 4 ROC curve for identifying patients with low PAL.

Notes: mMRC grade ≥2 was the most balanced cutoff point and yielded 51.7% sensitivity and 80.0% specificity (area under curve =0.66).
Abbreviations: mMRC, modified Medical Research Council; PAL, physical activity level; ROC, receiver operating characteristic.