論文の公開元へAssociations of pulmonary and extrapulmonary computed tomographic manifestations with impaired physical activity in symptomatic patients with chronic obstructive pulmonary disease
概要
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Associations of pulmonary
and extrapulmonary computed
tomographic manifestations
with impaired physical activity
in symptomatic patients
with chronic obstructive pulmonary
disease
Yoko Hamakawa1, Naoya Tanabe1*, Hiroshi Shima1, Kunihiko Terada2, Yusuke Shiraishi1,
Tomoki Maetani1, Takeshi Kubo3, Satoshi Kozawa4, Koji Koizumi4, Masashi Kanezaki5,
Kaoruko Shimizu6, Tsuyoshi Oguma1, Atsuyasu Sato1, Susumu Sato1 & Toyohiro Hirai1
In patients with chronic obstructive pulmonary disease (COPD), emphysema, airway disease,
and extrapulmonary comorbidities may cause various symptoms and impair physical activity. To
investigate the relative associations of pulmonary and extrapulmonary manifestations with physical
activity in symptomatic patients, this study enrolled 193 patients with COPD who underwent chest
inspiratory/expiratory CT and completed COPD assessment test (CAT) and the Life-Space Assessment
(LSA) questionnaires to evaluate symptom and physical activity. In symptomatic patients (CAT ≥ 10,
n = 100), emphysema on inspiratory CT and air-trapping on expiratory CT were more severe and
height-adjusted cross-sectional areas of pectoralis muscles (PM index) and adjacent subcutaneous
adipose tissue (SAT index) on inspiratory CT were smaller in those with impaired physical activity
(LSA < 60) than those without. In contrast, these findings were not observed in less symptomatic
patients (CAT < 10). In multivariable analyses of the symptomatic patients, severe air-trapping and
lower PM index and SAT index, but not CT-measured thoracic vertebrae bone density and coronary
artery calcification, were associated with impaired physical activity. These suggest that increased airtrapping and decreased skeletal muscle and subcutaneous adipose tissue quantity are independently
associated with impaired physical activity in symptomatic patients with COPD.
Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation induced by a combination
of airway disease and emphysema in the lungs1. COPD is also characterized by extrapulmonary comorbidities such as muscle wasting, underweight, osteoporosis, and cardiovascular d
isease2,3. These pulmonary and
extrapulmonary manifestations may cause physical inactivity and sedentary l ifestyle4,5, leading to poor prognosis
in patients with C
OPD6,7. However, due to the complex mixtures of the manifestations in and outside the lungs,
determinants of decreased physical activity remain not fully understood and no personalized program to increase
physical activity is currently available.
1
Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, 54 Kawahara‑cho,
Shogoin, Sakyo‑ku, Kyoto 606–8507, Japan. 2Terada Clinic, Respiratory Medicine and General Practice, Himeji,
Hyogo, Japan. 3Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine,
Kyoto University, Kyoto, Japan. 4Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto,
Japan. 5Department of Physical Therapy, School of Health Sciences, Tokyo International University, Kawagoe,
Saitama, Japan. 6Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, Sapporo,
Japan. *email: ntana@kuhp.kyoto-u.ac.jp
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Figure 1. Patients’ flow and the distribution of COPD assessment test and Life-Space Assessment scores. Based
on COPD assessment test (CAT) score of 10 and Life-Space Assessment (LSA) score of 60, patients were divided
into 4 groups: (1) those with low CAT and high LSA (less symptomatic and physically active, n = 82), (2) low
CAT and low LSA (less symptomatic and physically inactive, n = 11), (3) high CAT and high LSA (symptomatic
and physically active, n = 73), (4) high CAT and low LSA (symptomatic and physically inactive, n = 27).
Airflow limitation induces air-trapping on expiration and lung hyperinflation that increase exertional dyspnea and daily s ymptoms8. While studies have shown associations of symptoms with physical inactivity9,10, the
associations are modest. Indeed, symptomatic relief induced by bronchodilators and lung volume reductions
in interventional studies is not always correlated with an increased physical activity11,12. Moreover, patients
with COPD tend to avoid symptoms by decreasing physical a ctivity13 and might be classified as those with less
symptom and impaired physical activity. The discrepancy between symptoms and physical activity could also
be accounted for by the extrapulmonary manifestations such as skeletal muscle loss and reduced bone mineral
density, which have been shown to be associated with impaired physical activity5,14,15. Collectively, these findings
suggest that factors associated with physical activity should be explored in symptomatic and less symptomatic
patients, separately, by focusing on both the pulmonary and extrapulmonary manifestations.
Chest inspiratory and expiratory computed tomography allows simultaneously quantifying emphysema,
airway disease, and air-trapping in the lungs16, as well as pectoralis muscle, erector spinae muscle, subcutaneous adipose tissue, bone mineral density (BMD) on thoracic vertebrae and coronary artery calcification outside
the lungs17–23. Waschki et al. showed that emphysema severity on CT was associated with impaired physical
activity4, whereas Tanimura et al. showed that a reduction in both pectoralis and erector spinae muscles was
associated with a lower daily step count19. However, little is known about relative associations of the pulmonary
and extrapulmonary CT findings with impaired physical activity in patients with COPD.
It was hypothesized that the lung pathophysiology and extrapulmonary manifestations are independently
associated with impaired physical activity in patients with symptomatic COPD, but not those with less symptomatic COPD. Therefore, this study categorized patients with COPD based on symptom and physical inactivity
using two questionnaires; COPD assessment test (CAT)1 and the Life-Space Assessment (LSA), which is easily
performed to estimate physical activity by evaluating the extent of social isolation and sedentary lifestyle24.
Then, the study aimed to compare the pulmonary and extrapulmonary CT findings of symptomatic and physically inactive patients to those of the remaining. Furthermore, the study constructed multivariable models to
test whether the pulmonary and extrapulmonary CT findings could be independently associated with impaired
physical activity in symptomatic patients.
Results
Patients’ characteristics. As shown in Fig. 1, of 362 smokers initially evaluated, 221 met the diagnostic
criteria of COPD, but 26 were excluded because of incomplete CAT and/or LSA questionnaires and 2 were
excluded because of inadequate CT quality. Total 193 patients with COPD were included for the present analyses
and their demographics are shown in Table 1. As shown in Fig. 1B, based on CAT score of 10 and LSA score of
60, patients were divided into 4 groups: (1) those with low CAT and high LSA (less symptomatic and physically
active, n = 82), (2) low CAT and low LSA (less symptomatic and physically inactive, n = 11), (3) high CAT and
high LSA (symptomatic and physically active, n = 73), (4) high CAT and low LSA (symptomatic and physically
inactive, n = 27).
Clinical physiological features in symptomatic and physically inactive patients. As shown in
Table 2, age, sex, smoking pack-years, height, number of exacerbations in a previous year, long-acting beta
agonist (LABA) use, and inhaled corticosteroid (ICS) use did not differ between the 4 groups. The symptomatic
and physically inactive patients (CAT ≥ 10 and LSA < 60) showed lower body mass index (BMI) and percent
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N
193
Age, years
72.5 ± 7.7
Male, n (%)
180 (93%)
Current smokers, n (%)
44 (23%)
Pack-years
60.2 ± 30.9
Height, cm
164.7 ± 7.1
BMI, kg/m2
23.2 ±
BMI ≥ 30 kg/m2, n (%)
6 (3%)
FEV1, % predicted
62.6 ± 22.6
FVC, % predicted
89.3 ± 22.0
FEV1 / FVC
0.53 ± 0.12
No. exacerbations in a previous year, 0/1/ ≥ 2
148/37/8
mMRC, 0/1/2/3/4
74 / 74 / 27 / 12 / 6
CAT ≥ 10, n (%)
100 (52%)
LSA ≤ 60, n (%)
38 (20%)
GOLD, 1/2/3/4
43/95/36/19
ABCD category, A / B / C / D
87/98/0/8
Table 1. Patients’ Characteristics. Data are expressed as mean ± SD and n (%). BMI = body mass index,
Exacerbation in a past year = a history of at least one exacerbation in the previous one year, mMRC = modified
MRC dyspnea scale, FEV1 = forced expiratory volume in 1 s, CAT = COPD assessment test, LSA = life space
assessment.
Less symptomatic
(CAT < 10)
Symptomatic (CAT ≥ 10)
LSA > 60
(n = 82)
LSA > 60
(n = 73)
LSA ≤ 60
(n = 11)
LSA ≤ 60
(n = 27)
Age
72.1 ± 6.4
74.0 ± 6.9
71.9 ± 8.4
74.3 ± 9.6
Male, n (%)
79 (96%)
9 (82%)
67 (92%)
25 (93%)
Pack-years
60.0 ± 30.7
76.1 ± 39.2
57.8 ± 28.7
60.9 ± 33.7
Height, cm
166.7 ± 6.5
160.2 ± 8.4
164.9 ± 6.9
163.3 ± 8.3
BMI, kg/m2
23.8 ± 3.2
23.3 ± 3.0
23.6 ± 3.6
20.0 ± 4.2*†‡
No. ...
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