Patients characteristics
| Total | Other-SSc | SSc-emphysema | SSc-ILD | SSc-CPFE | P value | |
| n (%) | 470 (100) | 202 (43) | 29 (6) | 196 (42) | 43 (9) | – |
| Age, mean (year) (95% CI) | 59.2 (57.2 to 60.5) | 59.3 (57.3 to 61.3) | 59.8 (54.8 to 64.9) | 59.4 (57.4 to 61.3) | 57.7 (53.3 to 62.1) | nss |
| Sex (M:F) | 90:380 | 30:172 | 8:21 | 36:160 | 16:27 | (CPFE vs SSc-ILD)** (CPFE vs Other-SSc)*** |
| Disease duration, mean (year) (95% CI) | 8.2 (7.4 to 8.9) | 7.8 (6.6 to 9.0) | 8.4 (5.3 to 11.5) | 8.4 (7.4 to 9.5) | 8.6 (6.1 to 11) | nss |
| Smoke habit‡ (none:former:current) | 351:57:52 | 165:17:19 | 17:5:6 | 146:28:18 | 25:7:9 | (CPFE vs Other-SSc)** (SSc-Emphysema vs Other-SSc)* |
| ACA prevalence (n) | 160 | 107 | 21 | 27 | 5 | (CPFE vs SSc-Other)§ (CPFE vs SSc-Emphysema)§ (SSc-ILD vs SSc-Emphysema)§ (SSc-Other vs SSc-Emphysema)* (Other-SSc vs SSc-ILD)§ |
| anti Scl70 prevalence (n) | 154 | 23 | 0 | 113 | 18 | (CPFE vs SSc-Emphysema)*** (CPFE vs Other-SSc)§ (SSc-ILD vs SSc-Emphysema)§ (SSc-ILD vs Other-SSc)§ |
| FVC-predicted, mean (95% CI) | 99% (97 to 102) | 109% (105 to 113) | 103% (92 to 114) | 91% (88 to 95) | 88% (80 to 95) | (CPFE vs Other-SSc)† (CPFE vs SSc-Emphysema)** (Other-SSc vs SSc-ILD)† (SSc-ILD vs SSc-Emphysema)* |
| TLC-predicted, mean (95% CI) | 93% (90 to 95) | 99% (96 to 103) | 104% (93 to 116) | 85% (81 to 89) | 82% (76 to 88) | (CPFE vs Other-SSc)† (CPFE vs SSc-Emphysema)† (SSc-ILD vs SSc-Emphysema)† (Other-SSc vs SSc-ILD)† |
| DLco-predicted, mean (95% CI) | 65% (63 to 67) | 73% (70 to 75) | 63% (55 to 65) | 61% (58 to 64) | 48% (42 to 55) | (CPFE vs Other-SSc)† (CPFE vs SSc-ILD)† (CPFE vs SSc-Emphysema)** (SSc-Other vs SSc-Emphysema)* (Other-SSc vs SSc-ILD)*** |
| DLco/VA-predicted, mean (95% CI) | 82% (80 to 85) | 85% (81 to 88) | 83% (75 to 91) | 85% (81 to 89) | 59% (52 to 67) | (CPFE vs SSc-ILD)† (CPFE vs Other-SSc)† (CPFE vs SSc-Emphysema)† |
| ILD extent >20%, n (%) | 95 (20) | 0 (0) | 0 (0) | 74 (38) | 21 (49) | (CPFE vs Other-SSc)§ (CPFE vs SSc-Emphysema)§ (SSc-ILD vs SSc-Emphysema)§ (Other-SSc vs SSc-ILD)§ |
| sQCT of ILD, median (95% CI) | 1% (0 to 3) | 0 | 0 | 15% (13 to 17) | 20% (18 to 26) | (CPFE vs Other-SSc)† (CPFE vs SSc-ILD)** (CPFE vs SSc-Emphysema)† (SSc-ILD vs SSc-Emphysema)† (Other-SSc vs SSc-ILD)*** |
| sQCT of emphysema, median (95% CI) | 0 | 0 | 4% (2 to 10) | 0 | 4% (2 to 7) | (CPFE vs SSc-ILD)† (CPFE vs Other-SSc)† (SSc-Emphysema vs SSc-ILD)† (SSc-Emphysema vs Other-SSc)† |
A graphical presentation of key findings is in the online supplementary file 1.
*<0.05; **<0.01; ***<0.001.
†<0.005.
‡Ten patients had an unknown smoke habit.
§<0.0001.
ACA, anticentromere antibodies; CPFE, combined pulmonary fibrosis and emphysema; DLco, diffusion lung capacity of CO; FVC, forced vital capacity; ILD, interstitial lung disease; IPF, Idiopathic pulmonary fibrosis; SSc, systemic sclerosis; TLC, Total lung capacity; VA, alveolar volume.