Baseline characteristics of studied population and population for external validation of CAno threshold
| All SSc patients (n=105) | SSc population for validation (n=48) | p Value | |
| Demographics | |||
| Age, years | 54.8±12.9 | 56.1±12.7 | 0.564 |
| Men | 13 (12.4) | 10 (20.8) | 0.174 |
| Smoking status | |||
| Never smoking | 83 (79.0) | 47 (97.9) | 0.005 |
| Ex-smoker | 12 (10.5) | 0 (0) | 0.030 |
| Current smoker | 10 (9.5) | 1 (2.1) | 0.181 |
| Systemic sclerosis | |||
| Duration of disease (years) | 11.4±11.6 | 7.9±5.8 | 0.014 |
| Diffuse SSc | 35 (33.3) | 18 (37.5) | 0.615 |
| Lung disease | |||
| Presence of ILD | 51 (48.6) | 23 (47.9) | 0.940 |
| FVC (%)* | 97±23 | 98±22 | 0.809 |
| Tlco (%)* | 63±17 | 61±19 | 0.583 |
| Pulmonary hypertension† | 6 (5.7) | 1 (2.1) | 0.564 |
| Treatment | |||
| Immunosuppressive therapy | 17 (16.2) | 13 (27.1) | 0.105 |
| Partitioned exhaled nitric oxide | |||
| CAno (ppb) | 6.9±5.5 | 7.2±5.7 | 0.814 |
| J′awno (ml/min) | 29.0±20.4 | 30.8±10.3 | 0.695 |
| FEno0.05 (ppb) | 16.6±12.1 | 17.4±10.3 | 0.663 |
Values are n (%) or mean±SD.
p Value significant if <0.05.
↵* Proportion of predicted value.
↵† Pulmonary hypertension measured by right heart catheterisation.
CAno, alveolar concentration of nitric oxide; Tlco, carbon monoxide transfer factor; FEno0.05, fractioned exhaled nitric oxide at 50 ml/min of outflow; FVC, forced vital capacity; ILD, interstitial lung disease; J′awno, conducting airway maximal nitric oxide output; ppb, parts per billion; SSc, systemic sclerosis.