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/m2)	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/m2)	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.