Demographics and baseline characteristics
| Characteristic | Pooled selexipag | Pooled control |
| Patients n | 329 | 320# |
| Female, n (%) | 256 (77.8) | 249 (77.8) |
| Age years, mean±sd | 47.3±15.1 | 47.0±15.7 |
| Time since PAH diagnosis days, median (Q1–Q3) | 24.4 (12.2–82.4) | 24.4 (9.2–67.1) |
| PAH aetiology, n (%) | ||
| Idiopathic | 158 (48.0) | 174 (54.4) |
| Associated with connective tissue disease | 109 (33.1) | 102 (31.9) |
| Associated with congenital heart disease | 26 (7.9) | 24 (7.5) |
| Drug- or toxin-induced | 18 (5.5) | 7 (2.2) |
| Heritable | 13 (4.0) | 8 (2.5) |
| Associated with HIV infection | 5 (1.5) | 5 (1.6) |
| Geographical region, n (%) | ||
| North America | 84 (25.5) | 82 (25.6) |
| Rest of the world | 245 (74.5) | 238 (74.4) |
| BMI kg·m−2, mean±sd | 26.9±5.8 | 26.2±5.9 |
| 6MWD m, mean±sd | 346.8±96.0 | 342.3±99.6 |
| NT-proBNP, n (%)¶ | ||
| Low risk (<300 ng·L−1) | 104 (31.6) | 84 (26.3) |
| Medium risk (300–1400 ng·L−1) | 104 (31.6) | 110 (34.4) |
| High risk (>1400 ng·L−1) | 116 (35.3) | 122 (38.1) |
| WHO FC, n (%) | ||
| I/II | 141 (42.9) | 123 (38.4) |
| III/IV | 188 (57.1) | 197 (61.6) |
| Other PAH therapy+, n (%) | 254 (77.2) | 238 (74.4) |
| ERA+PDE-5i | 145 (44.1)§ | 140 (43.8) |
| PDE-5i | 88 (26.7) | 77 (24.1) |
| ERA | 21 (6.4) | 21 (6.6) |
PAH: pulmonary arterial hypertension; HIV: human immunodeficiency virus; BMI: body mass index; 6MWD: 6-min walk distance; NT-proBNP: N-terminal pro-brain natriuretic peptide; WHO FC: World Health Organization functional class; ERA: endothelin receptor antagonist; PDE-5i: phosphodiesterase-5 inhibitor. #: n=318 for 6MWD; n=319 for BMI; ¶: data were missing for five selexipag and four control patients. +: PAH therapy was started >3 months before randomisation, except for the 121 and 123 patients from TRITON who started ERA+PDE-5i therapy at randomisation. §: one TRITON patient received background PDE-5i therapy prior to randomisation.