TABLE 1.
Summary of patient demographics and clinical characteristics for the two patient cohorts included in this study
| Zurich cohort (n=90) | Oslo cohort (n=66) | p-value | |
| Age (years) | 57.5±17.8 | 61.0±18.8 | 0.641 |
| Sex | |||
| Male | 21 (23.3) | 16 (24.2) | 1.000 |
| Female | 69 (76.7) | 50 (75.8) | |
| SSc disease duration (years)# | 5.0±8.2 | 5.3±9.2 | 0.874 |
| SSc subset [18] | |||
| Limited cutaneous SSc | 41 (45.6) | 37 (56.1) | 0.041* |
| Diffuse cutaneous SSc | 42 (46.7) | 29 (43.9) | |
| No skin involvement | 7 (7.8) | 0 (0.0) | |
| Skin involvement | |||
| Limited cutaneous | 31 (34.4) | 37 (56.1) | <0.001* |
| Diffuse cutaneous | 43 (47.8) | 29 (43.9) | |
| No skin involvement | 9 (10.0) | 0 (0.0) | |
| Only sclerodactyly | 7 (7.8) | 0 (0.0) | |
| Autoantibodies | |||
| Anti-centromere positive | 13 (14.4) | 7 (10.6) | 1.000 |
| Anti-topoisomerase 1 positive | 41 (45.6) | 24 (36.4) | 0.614 |
| Anti-RNA polymerase III positive | 7 (7.8) | 8 (12.1) | 0.261 |
| Anti-PM/Scl positive | 18 (20.0) | 4 (6.1) | 0.032* |
| FVC (% pred) | 87.5±33.9 | 85.0±36.0 | 0.605 |
| ≥70% pred | 64 (71.1) | 44 (66.7) | 0.851 |
| <70% pred | 24 (26.7) | 15 (22.7) | |
| DLCO (% pred) | 66.5±29.4 | 61.0±29.0 | 0.078 |
| FEV1 (% pred) | 88.7±31.2 | 77.0±26.5 | 0.088 |
| Pulmonary hypertension¶ | 20 (22.2) | 6 (9.1) | 0.048* |
| PAPsys (mmHg)+ | 26.0±10.0 | 21.0±20.0 | 0.028* |
| CRP (mg·L−1) | 3.1±5.6 | 3.6±8.0 | 0.259 |
| 6-min walk distance (m) | 511.0±161.0 | NA | NA |
| SpO2 before 6MWT (%) | 96.0±2.0 | NA | NA |
| SpO2 after 6MWT (%) | 95.0±7.0 | NA | NA |
| Borg scale (range 0–10) | 3.0±2.0 | NA | NA |
| Extent of lung fibrosis on HRCT | |||
| <20% | 50 (55.6) | 30 (45.5) | 0.257 |
| ≥20% | 40 (44.4) | 36 (54.5) | |
| Ground-glass opacification | 45 (50.0) | 42 (63.6) | 0.104 |
| Reticular changes | 87 (96.7) | 51 (77.3) | <0.001* |
| Traction bronchiectasis | 50 (55.6) | 27 (40.9) | 0.077 |
| Honeycombing | 22 (24.4) | 16 (24.2) | 1.000 |
| Bullae | 3 (3.3) | 4 (6.1) | 0.457 |
| Radiological subtype | |||
| NSIP | 49 (54.4) | 34 (51.5) | 0.602 |
| UIP§ | 37 (41.1) | 27 (40.9) | |
| DIP | 1 (1.1) | 0 (0.0) | |
| Unclassifiable | 3 (3.3) | 5 (7.6) | |
| Immunomodulatory therapyƒ | 51 (56.7) | 28 (42.4) | 0.105 |
| Smoking status | |||
| Never-smoker | 55 (61.1) | 24 (36.4) | 0.025* |
| Ex-smoker | 21 (23.3) | 25 (37.9) | |
| Current smoker | 12 (13.3) | 5 (7.6) | |
| Died during follow-up## | 20 (22.2) | 22 (33.3) | 0.009* |
| Relative FVC decline ≥15% during follow-up | 27 (30.0) | 11 (16.7) | 0.113 |
| Visual HRCT progression during follow-up | 21 (23.3) | 18 (27.3) | 0.316 |
Data are presented as median±interquartile range or n (%), unless otherwise stated. SSc: systemic sclerosis; FVC: forced vital capacity; DLCO: diffusing capacity of the lung for carbon monoxide; FEV1: forced expiratory volume in 1 s; PAPsys: systolic pulmonary arterial pressure; CRP: C-reactive protein; NA: not available; SpO2: peripheral oxygen saturation; 6MWT: 6-min walk test; HRCT: high-resolution computed tomography; NSIP: nonspecific interstitial pneumonia; UIP: usual interstitial pneumonia; DIP: diffuse interstitial pneumonia. #: disease duration of SSc was calculated as the difference between the date of baseline CT and the date of manifestation of the first non-Raynaud's symptom; ¶: pulmonary hypertension was assessed by echocardiography or right heart catheterisation; +: PAPsys was determined by right heart catheterisation; §: UIP includes the radiological diagnosis of both “definite” and “probable” UIP; ƒ: immunomodulatory therapy included prednisone, methotrexate, rituximab, cyclophosphamide, mycophenolate mofetil, hydroxychloroquine, tocilizumab, imatinib, azathioprine, adalimumab, leflunomide and cyclosporine; ##: cause of death included SSc-associated interstitial lung disease, pulmonary arterial hypertension, viral pneumonia, pulmonary embolism, septic shock, brain haemorrhage, caecal cancer, pancreatic carcinoma and lung cancer. p-values of univariate comparisons of baseline characteristics between the two cohorts are shown. Fisher's exact test was used to compare categorical variables and the Mann–Whitney U-test was used to compare continuous variables. *: p<0.05.