Personalized pulmonary rehabilitation and occupational therapy based on cardiopulmonary exercise testing for patients with advanced chronic obstructive pulmonary disease

Figures & data

Figure 1 Study designs of (A) the retrospective control study and (B) the prospective observational study.

Note: *Indicates the number of patients included in the survival analyses.
Abbreviations: COPD, chronic obstructive pulmonary disease; CPET, cardiopulmonary exercise testing; GOLD, Global Initiative for Chronic Obstructive Lung Disease; MRC, Medical Research Council; PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy; HOT, home oxygen therapy.

Figure 2 Determination of a safe range using partial pressure of arterial oxygen (PaO₂), NE, and the Borg scale during CPET.

Notes: We measured hypoxemia (PaO₂ <60 mmHg), the NE threshold, and breathlessness onset for each individual during exercise. The NE threshold was determined by using a log-log transformation of the NE–oxygen uptake relationship. The criteria for the safe range were 1) PaO₂ >60 mmHg and 2) lower than the NE threshold and/or Borg scale score of <2. These variables were used together to determine the safe range as indicated by oxygen uptake (mL/min), which was determined from each patient’s SpO₂ (%) reading and pulse rate (beats/min) using a watch-type pulse oximeter, in addition to the Borg scale. The yellow triangles indicates PaO₂; the pink squares indicates norepinephrine (NE); the dark blue diamond is the Borg scale. The dotted line indicates oxygen uptake at the point of NT.
Abbreviations: CPET, cardiopulmonary exercise testing; NE, norepinephrine; NT, norepinephrine threshold; PaO₂, partial pressure of arterial oxygen.

Table 1 Comparison of descriptive characteristics and peak CPET variables in 107 patients with COPD in the retrospective study

Group Variables	PPR-OT group	Control group	Comparison P-values
	n=46 (M:F, 44:2)	n=61 (M:F, 57:4)
	Mean ± SD	Mean ± SD
Descriptive characteristics
Age (years)	68.7±7.1	68.5±6.7	0.4185
BMI (kg/m^2)	19.7±2.7	19.0±3.1	0.3866
FEV1(L)	0.80±0.23	0.81±0.24	0.5381
FEV1/FVC (%)	36.7±8.4	37.1±13.6	0.5689
FEV1(% predicted)	30.6±9.1	30.4±9.7	0.4635
FVC (L)	2.25±0.66	2.28±0.72	0.5905
FVC (% predicted)	70.3±18.6	71.4±21.4	0.6199
Heart rate (beats/min)	88.9±13.9	89.8±12.6	0.642
pH	7.425±0.022	7.420±0.021	0.1267
PaO2 (mmHg)	76.7±11.0	75.6±11.2	0.3101
PaCO2 (mmHg)	38.1±4.4	39.8±5.0	0.9654
Peak CPET variables
Heart rate (beats/min)	121±18	123±22	0.683
Respiratory frequency (/min)	33.5±7.4	33.2±10.4	0.4155
Tidal volume (mL)	942±224	940±312	0.4865
Minute ventilation (L/min)	30.7±9.1	29.5±9.3	0.2509
Oxygen uptake (mL/min)	693±192	705±273	0.605
Oxygen uptake/kg	13.6±3.8	13.6±4.3	0.5086
Carbon dioxide output (mL/min)	619±197	630±291	0.6019
Oxygen pulse (mL/beat)	5.8±1.7	5.6±1.9	0.2718
Respiratory ratio	0.89±0.11	0.87±0.19	0.2911
Ventilatory equivalent for O2	48.0±11.2	45.4±12.1	0.126
Ventilatory equivalent for CO2	51.0±13.4	49.5±16.7	0.2982
pH	7.362±0.031	7.351±0.042	0.0545
PaO2 (mmHg)	57.8±11.3	59.4±12.7	0.7543
PaCO2 (mmHg)	44.2±5.9	45.6±6.9	0.8594
PaO2 slope (mmHg·L^−1·min^−1)	−52.3±36.6	−48.8±43.6	0.6763

Notes: The PaO₂ slope (mmHg·L⁻¹·min⁻¹) is the decrease in ${\text{PaO}}_2/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2.\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$ is the difference in ${\dot{\mathrm{V}}\mathrm{O}}_2$ between the values at rest and peak exercise.

Abbreviations: BMI, body mass index; COPD, chronic obstructive pulmonary disease; CPET, cardiopulmonary exercise testing; F, female; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; M, male; PaCO₂, partial arterial pressure of carbon dioxide; PaO₂, partial arterial pressure of oxygen; PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy; SD, standard deviation.

Table 2 Univariate and multivariate analyses of descriptive characteristics and peak CPET variables associated with mortality from any cause in the retrospective study

Variables	Risk ratio	95% CI	P-value
Univariate analysis
PPR-OT	0.389	0.172–0.800	0.0094
Descriptive characteristics
Age (years)	1.061	1.008–1.120	0.0246
BMI (kg/m^2)	0.811	0.710–0.920	0.001
FEV1 (L)	0.182	0.040–0.794	0.0228
FEV1/FVC (%)	1.002	0.967–1.038	0.8948
FEV1 (% predicted)	0.97	0.934–1.005	0.0906
FVC (L)	0.583	0.360–0.954	0.0318
FVC (% predicted)	0.981	0.965–0.997	0.0202
Heart rate (beats/min)	1.009	0.984–1.036	0.482
PaO2 (mmHg)	1.002	0.973–1.032	0.9055
PaCO2 (mmHg)	1.07	0.999–1.144	0.055
Peak CPET variables
Heart rate (beats/min)	0.987	0.974–1.003	0.1089
Respiratory frequency (/min)	0.985	0.939–1.029	0.524
Tidal volume (mL)	0.998	0.997–0.999	0.0129
Minute ventilation (L/min)	0.934	0.892–0.973	0.0007
Oxygen uptake (mL/min)	0.997	0.996–0.999	0.0024
Oxygen uptake/kg	0.931	0.852–1.012	0.0957
Carbon dioxide output (mL/min)	0.997	0.995–0.999	0.0003
Oxygen pulse (mL/beat)	0.769	0.616–0.940	0.0068
Respiratory ratio	0.183	0.051–0.958	0.045
Ventilatory equivalent for O2	1.005	0.977–1.028	0.6984
Ventilatory equivalent for CO2	1.012	0.992–1.028	0.2298
PaO2 (mmHg)	0.995	0.967–1.023	0.7354
PaCO2 (mmHg)	1.065	1.012–1.120	0.0167
PaO2 slope (mmHg·L^−1·min^−1)	0.984	0.977–0.991	<0.0001
Multivariate analysis
PPR-OT	0.322	0.138–0.687	0.0029
Descriptive characteristics
Age (years)	1.092	1.028–1.164	0.0039
BMI (kg/m^2)	0.875	0.756–1.004	0.0577
FEV1 (L)	0.322	0.041–2.246	0.2582
Peak CPET variables
Tidal volume (mL)	1	0.998–1.003	0.7103
Oxygen uptake (mL/min)	0.999	0.996–1.003	0.7092
PaCO2 (mmHg)	1.059	0.992–1.131	0.0851
PaO2 slope (mmHg·L^−1·min^−1)	0.988	0.977–0.999	0.0333

Notes: The PaO₂ slope (mmHg·L⁻¹·min⁻¹) is the decrease in ${\text{PaO}}_2/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2.\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$ is the difference in ${\dot{\mathrm{V}}\mathrm{O}}_2$ between the values at rest and peak exercise.

Abbreviations: BMI, body mass index; CI, confidence interval; CPET, cardiopulmonary exercise testing; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; PaCO₂, partial arterial pressure of carbon dioxide; PaO₂, partial arterial pressure of oxygen; PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy.

Table 3 Comparison of the cause of death between patients in the PPR-OT and control groups in the retrospective control study

Causes of death	PPR-OT (n=46)	Control group (n=61)
Respiratory failure	3*	18
Sudden death	1	2
Cardiovascular events	1	2
Malignant diseases	1	1
Other diseases	2	1
Total	8 (17.4%)*	24 (38.7%)
Observation period (years)	4.51±0.9	3.9±1.4

Note:

* P<0.0001, based on the chi-squared test.

Abbreviation: PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy.

Figure 3 Effect of the personalized pulmonary rehabilitation program that included occupational therapy (PPR-OT) on the 5-year survival (all-cause mortality) of patients with COPD after CPET in the retrospective study.

Abbreviations: COPD, chronic obstructive pulmonary disease; CPET, cardiopulmonary exercise testing.

Table 4 Comparison of the descriptive characteristics and management between both groups in the prospective observational study

Number of cases	PPR-OT group (n=85); mean ± SD	Control group (n=47); mean ± SD	P-values
Parameters at rest
M:F ratio	78:7	34:13
Age (years)	70.7±6.1	71.3±10.0	0.6612
Body length (cm)	161.0±6.7	159.6±9.7	0.3246
Body weight (kg)	51.3±8.9	51.2±11.0	0.9686
BMI (kg/m^2)	19.8±3.0	20.0±3.3	0.6589
FEV1 (L)	0.82±0.31	0.77±0.33	0.3437
FEV1/FVC (%)	39.3±11.5	46.4±14.3	0.0024
FEV1(% predicted)	31.5±11.4	32.3±13.0	0.6951
FVC (L)	2.14±0.65	1.73±0.67	0.0008
FVC (% predicted)	67.9±18.2	59.2±19.1	0.012
Medication, n (%)
Anticholinergics	63 (74.1%)	29 (61.7%)	0.1404a
β2 agonists	54 (63.5%)	25 (53.2%)	0.2473a
Glucocorticosteroids	50 (58.8%)	20 (42.6%)	0.0726a
Theophylline	64 (75.3%)	21 (44.7%)	0.0005a
Visiting nurse service, n (%)	43 (50.6%)	11 (23.4%)	0.0019a
NIV, n (%)	11 (12.9%)	4 (8.5%)	0.4334a
Admission rate (events/y)	0.70±0.50	0.73±1.00	0.4252

Notes: Age (years): Age at the prescription of HOT.

a The comparison between the two groups uses unpaired t-tests or the chi-squared test.

Abbreviations: BMI, body mass index; F, female; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; M, male; NIV, noninvasive ventilation; PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy; SD, standard deviation.

Table 5 Comparison of the causes of death between the PPR-OT group and the control group in the prospective observational study

Causes of death	PPR-OT group (n=85)	Control group (n=47)
Respiratory failure	14*	14
Sudden death	4**	1
Cardiovascular events	1	4
Malignant diseases	3	2
Other diseases	2	0
Total	24 (28.2%)*	21 (44.7%)
Observation period (years), mean ± SD	6.1±1.6	5.1±2.5

Notes:

* P<0.0001 and

** P=0.0059, based on the chi-squared test.

Abbreviations: PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy; SD, standard deviation.

Table 6 Univariate and multivariate analyses for management associated with mortality from any cause in 132 patients with COPD of the prospective observational study after HOT

Management	All patients
	Risk ratio	95% CI	P-value
Univariate analysis
PPR-OT	0.515	0.296–0.933	0.0291
Age	1.011	0.975–1.049	0.5739
Sex	1.04	0.496–2.541	0.9234
Medications
Anticholinergics	0.424	0.236–0.768	0.0051
β2 agonists	0.49	0.270–0.880	0.0173
Glucocorticosteroids	0.576	0.315–1.037	0.0658
Theophylline	1.075	0.588–2.053	0.8175
Visiting nurse service	0.927	0.502–1.671	0.8029
NIV	0.339	0.055–1.098	0.0757
Admission rate (events/y)	2.305	1.596–3.236	0.0001
Multivariate analysis
PPR-OT	0.532	0.287–0.991	0.0469
Medications
Anticholinergics	0.434	0.232–0.813	0.0096
β2 agonists	0.487	0.262–0.897	0.0212
Admission rate (events/y)	2.752	1.869–4.185	,0.0001

Abbreviations: BMI, body mass index; CI, confidence interval; COPD, chronic obstructive pulmonary disease; HOT, home oxygen therapy; NIV, noninvasive ventilation; PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy.

Figure 4 Effect of the personalized pulmonary rehabilitation program that included occupational therapy (PPR-OT) on the 5- to 7-year survival of patients with COPD undergoing HOT in the prospective observational study.

Notes: (A) all-cause mortality and (B) respiratory-related mortality after prescription of HOT. In the PPR-OT group, the 5-year survival was (A) 81.2% and (B) 90.6%; the 7-year survival was (A) 71.8% and (B) 83.5%. In the control group, the 5-year survival was (A) 66.0% and (B) 72.3%; the 7-year survival was (A) 53.2% and (B) 66.0%.
Abbreviations: COPD, chronic obstructive pulmonary disease; PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy; HOT, home oxygen therapy.

Table 7 Univariate analysis of descriptive characteristics, management, and peak CPET variables associated with mortality from any cause in 85 patients with COPD with PPR-OT after CPET

	Mean ± SD	Risk ratio	95% CI	P-value
Descriptive characteristics
Age (year)		1.082	1.002–1.167	0.0438*
BMI (kg/m^2)		0.852	0.718–0.996	0.0465*
FEV1(L)		0.309	0.051–1.503	0.1526
FEV1/FVC (%)		0.961	0.912–1.007	0.0892
FEV1(% predicted)		0.97	0.924–1.012	0.1674
GOLD (stage)		2.175	0.820–6.781	0.1214
FVC (% predicted)		1.001	0.976–1.027	0.9458
FVC (L)		0.805	0.400–1.660	0.5514
Management
Medication
Anticholinergics		0.605	0.266–1.493	0.2614
β2 agonists		0.727	0.325–1.686	0.4457
Glucocorticosteroids		0.528	0.232–1.181	0.1188
Theophylline		1.719	0.650–5.912	0.2947
Visiting nurse service		0.943	0.419–2.124	0.8866
NIV		0.285	0.016–1.352	0.1328
Admission rate (events/y)		1.402	0.700–2.538	0.3209
Variables at peak exercise
Heart rate (beats/min)	120±22	0.998	0.980–1.019	0.8191
Respiratory frequency (/min)	32.8±6.8	1.012	0.947–1.079	0.7173
Tidal volume (mL)	939±302	0.998	0.996–1.000	0.0954
Minute ventilation (L/min)	30.3±11.3	0.969	0.919–1.012	0.1706
Oxygen uptake (mL/min)	680±263	0.999	0.996–1.001	0.1896
Oxygen uptake/kg	13.1±4.3	0.976	0.872–1.081	0.6509
Oxygen pulse (mL/beat)	5.9±4.2	0.909	0.714–1.051	0.316
pH	7.361±0.036	2.35	2.921e–6 to 1,541,145	0.9014
PaO2 (mmHg)	56.9±10.9	1.022	0.978–1.064	0.3129
PaCO2 (mmHg)	44.0±7.3	0.977	0.910–1.045	0.5021
HCO3 (mM·L^−1)	24.5±3.4	0.959	0.836–1.109	0.5692
Lactate (mg·mL^−1)	2.7±1.2	0.864	0.496–1.293	0.5246
NE (ng·mL^−1)	2.1±1.5	1.156	0.819–1.461	0.358
$\Delta \text{pH}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2({\mathrm{L}}^{-1}·{\min }^{-1})$	−0.170±0.128	0.186	0.013–6.398	0.3157
PaO2 slope (mmHg·L^−1·min^−1)	−56.3±54.0	0.998	0.994–1.002	0.2288
$\Delta {\text{PaCO}}_2/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2(\text{mmHg}·{\mathrm{L}}^{-1}·{\min }^{-1})$	16.3±19.0	1.009	0.998–1.018	0.0976
$\Delta {\text{HCO}}_3/\Delta {\text{VO}}_2(\text{mM}/\mathrm{L}/\mathrm{L}·{\min }^{-1})$	0.17±6.08	1.006	0.969–1.040	0.7285
$\Delta \text{NE}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2(\text{ng}/\text{mL}/\mathrm{L}\cdot {\min }^{-1})$	3.9±3.7	1.146	1.004–1.276	0.0445*
$\Delta \text{Lactate}/\Delta {\text{VO}}_2(\text{mg}/\text{mL}/\mathrm{L}\cdot {\min }^{-1})$	4.2±5.3	1.02	0.923–1.073	0.6033

Notes: Δ= difference between values at rest and peak exercise; $\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$ = the difference in ${\dot{\mathrm{V}}\mathrm{O}}_2$ between values at rest and peak exercise; $\Delta \text{pH}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2{(\text{L}}^{-1}\cdot {\min }^{-1})$ = the decrease in $\text{pH}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$ ; PaO₂ slope (mmHg⋅L⁻¹⋅min⁻¹) = the decrease in ${\text{PaO}}_2/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$ ; $\Delta {\text{PaCO}}_2/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2(\text{mmHg}\cdot {\mathrm{L}}^{-1}\cdot {\min }^{-1})$ = the difference in ${\text{PaCO}}_2/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$ ; $\Delta {\text{HCO}}_3/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2({\text{mM L}}^{-1}/\mathrm{L}·{\min }^{-1})$ = the difference in ${\text{HCO}}_3/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$ ; $\Delta \text{NE}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2({\text{ng mL}}^{-1}/\mathrm{L}\cdot {\min }^{-1})$ = the increase in $\text{NE}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$ ; $\Delta \text{Lactate}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2({\text{mg mL}}^{-1}/\mathrm{L}\cdot {\min }^{-1})$ = the increase in $\text{lactate}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$. The values are presented as the mean ± SD.

* P<0.05.

Abbreviations: BMI, body mass index; CI, confidence interval; COPD, chronic obstructive pulmonary disease; CPET, cardiopulmonary exercise testing; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; NE, norepinephrine; NIV, noninvasive ventilation; PaCO₂, partial arterial pressure of carbon dioxide; PaO₂, partial arterial pressure of oxygen; PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy; SD, standard deviation; ${\dot{\mathrm{V}}\mathrm{O}}_2$, oxygen uptake.

Figure 5 Effectiveness of the PPR-OT program against the three life-threatening conditions in 85 patients with COPD undergoing HOT.

Notes: The Kaplan–Meier curves for time to death (ie, all-cause mortality) are shown, based on distributions of the three life-threatening pathophysiological conditions: (A) PaO₂ slope, (B) $\Delta \text{pH}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$, and (C) $\Delta \text{NE}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$ after CPET in 85 patients with COPD in the PPR-OT group for 7-year survival, and in comparison with the reference group (no PPR-OT) with each life-threatening pathophysiological condition in previous reports for 5-year survival. Identification of three exercise-induced mortality risk factors in patients with COPD, Yoshimura K, Maekura R, Hiraga T, et al, COPD. 11(6), Copyright © 2014, Informa Healthcare USA, Inc.¹¹ This analysis was conducted to compare the survival rates of patients with (ie, Group A) and without (ie, Group B) each life-threatening pathophysiological condition in the PPR-OT group and compare the survival rates between Group A and Reference group with these conditions but no PPR-OT in a previous study.¹¹ (A) Group A₁ (partial arterial pressure of oxygen [PaO₂] slope ≤−55 mmHg L⁻¹min⁻¹): the 5-year survival is 86.2%. Reference group (PaO₂ slope ≤−55 mmHg L⁻¹min⁻¹): the 5-year survival is 52.2%. Group B₁ (PaO₂ slope ≥−55 mmHg L⁻¹min⁻¹). (B) Group A₂ $\left(\Delta \text{pH}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2\le -1.72{\mathrm{L}}^{-1}{\min }^{-1}\right)$: the 5-year survival is 84.5%. Reference group $\left(\Delta \text{pH}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2\le -1.72{\mathrm{L}}^{-1}{\min }^{-1}\right)$: the 5-year survival is 50.0%. Group B₂ $\left(\Delta \text{pH}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2>-1.72{\mathrm{L}}^{-1}{\min }^{-1}\right)$. (C) Group A₃ $(\Delta \text{NE}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2\ge 5.2\text{ng}/{\text{mL}\mathrm{L}}^{-1}{\min }^1)$: the 5-year survival is 81.3%. Reference group $\left(\Delta \text{NE}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2\ge 5.2\text{ng}/\text{mL}{\mathrm{L}}^{-1}{\min }^{-1}\right)$: the 5-year survival is 58.3%. Group B $(\Delta \text{NE}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2<5.2\text{ng}/\text{mL}{\mathrm{L}}^{-1}{\min }^{-1})$.
Abbreviations: $\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$, the difference in ${\dot{\mathrm{V}}\mathrm{O}}_2$ between values at rest and peak exercise; $\Delta \text{pH}/\Delta {\text{VO}}_2({\mathrm{L}}^{-1}\cdot {\min }^{-1})$, the decrease in $\text{pH}/\Delta {\dot{\mathrm{V}}\mathrm{O}}_2$; COPD, chronic obstructive pulmonary disease; CPET, cardiopulmonary exercise testing; HOT, home oxygen therapy; NE, norepinephrine; PaO₂, partial arterial pressure of oxygen; PPR-OT, personalized patient-specific pulmonary rehabilitation-occupational therapy; ${\dot{\mathrm{V}}\mathrm{O}}_2$, oxygen uptake.

Figure 6 Kaplan–Meier curves of time to death (all-cause mortality) using (A) the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification, (B) body mass index, and (C) peak ${\dot{\mathrm{V}}\mathrm{O}}_2$ distribution after cardiopulmonary exercise testing (CPET) in 85 patients with chronic obstructive pulmonary disease (COPD) in the personalized patient-specific pulmonary rehabilitation-occupational therapy (PPR-OT) group and comparison with the Reference group (no PPR-OT) in previous report.¹¹

Notes: The survival of patients with GOLD 4 is compared to that of patients in GOLD 3 and Reference (GOLD 4) groups. The 5-year survival of patients with GOLD 4 is 84.4%. The 5-year survival of the Reference group (GOLD 4) is 64.3%, (B) The survival of patients with a body mass index (BMI) <18 was compared to that of patients with a BMI ≥18 and Reference (ie, BMI <18) patients. The 5-year survival of patients with a BMI <18 is 81.5%; the 5-year survival of the Reference group (ie, BMI <18) is 60.7%. (C) The survival of patients with peak ${\dot{\mathrm{V}}\mathrm{O}}_2\le 593\text{mL}/\min$ is compared to that of patients with peak ${\dot{\mathrm{V}}\mathrm{O}}_2>593\text{mL}/\min$ and Reference patients (ie, peak ${\dot{\mathrm{V}}\mathrm{O}}_2\le 593\text{mL}/\min$). The 5-year survival of patients with peak ${\dot{\mathrm{V}}\mathrm{O}}_2\le 593\text{mL}/\min$ is 83.4%. The 5-year survival of the Reference group patients (ie, peak ${\dot{\mathrm{V}}\mathrm{O}}_2\le 593\text{mL}/\min$) is 45.8%.

Figure S1 We developed the watch-type pulse oximeter (PULSOX-M24, TEIJIN) in collaboration with Minolta Co. Ltd. The probe is attached to the ring finger, because of ease of pinching.

YoshimuraKMaekuraRHiragaTIdentification of three exercise-induced mortality risk factors in patients with COPDCOPD201411661562624914923

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