Table 4.
Univariate and multivariate Cox regression survival analyses.
| Parameter | Univariate HR (95% CI) | Multivariate HR (95% CI) |
|---|---|---|
| Age | 0.98 (0.96–1.00) | – |
| PVR (per 100 dyn·s/cm5 increase) | 1.10 (1.00–1.20) | 1.06 (0.92–1.22) |
| TAPSE/PASP ratio | 0.12 (0.03–0.57) | 0.27 (0.04–1.94)a |
| BNP (per 100 pg/mL) | 1.00 (0.97–1.10) | – |
| DLCO | 0.99 (0.97–1.00) | – |
| FEV1/VC max (per 10 units increase) | 1.00 (0.91–1.20) | – |
| FEV1 (per 10% pred increase) | 0.96 (0.87–1.10) | – |
| FVC | 0.99 (0.98–1.00) | 0.99 (0.98–1.00) |
| TLC | 0.99 (0.98–1.00) | – |
| 6MWD (per 10 m increase) | 0.95 (0.93–0.97) | 0.95 (0.92–0.99)a |
| SvO2 | 0.98 (0.95–1.00) | – |
| RAP | 1.00 (0.97–1.00) | – |
| Cardiac index | 0.90 (0.69–1.20) | – |
| mPAP (per 5 mm Hg increase) | 1.10 (1.00–1.20) | 1.00 (0.80–1.30) |
| Right atrial area | 1.00 (0.99–1.10) | – |
| PH-COPD severity | ||
| Severe vs. mild-to-moderate | 1.32 (0.88–1.99) | – |
| ESC/ERS risk score | ||
| Intermediate vs. low | 1.32 (0.91–1.93) | – |
| High vs. low | 2.34 (0.83–6.59) | – |
| BODE indexb | ||
| High (>6) vs. intermediate (3–6) | 0.526 (0.287–0.962) | – |
6MWD, 6-min walk distance; % pred, % predicted; BNP, brain natriuretic peptide; BODE, body mass index, obstruction, dyspnoea and exercise capacity; DLCO, lung diffusing capacity for carbon monoxide; ESC/ERS, European Society of Cardiology and European Respiratory Society; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; HR, hazard ratio; mPAP, mean pulmonary artery pressure; PASP, pulmonary artery systolic pressure; PH-COPD, pulmonary hypertension due to COPD; PVR, pulmonary vascular resistance; RAP, right atrial pressure; SvO2, mixed venous oxygen saturation; TAPSE, tricuspid annular plane systolic excursion; TLC, total lung capacity; VC, vital capacity.
Independently predicted mortality in a stepwise backward model [Step 4, HR (95% CI): TAPSE/PASP ratio, 0.22 (0.04–1.36); 6MWD per 10 m increase, 0.95 (0.92–0.98)].
Kaplan–Meier analysis revealed significant differences in survival between the three BODE index groups (Supplementary Figure 2), but no HR was computable for patients with a low BODE index (≤ 2) due to the small sample size. The BODE index was not included in the multivariate Cox regression analysis owing to a high number of missing values.