Characteristics of progressors and non-progressors according to clinical features and autoantibody status (at baseline)
| Characteristics | Progressor, n=66 (22.5%) | Non-progressor, n=227 (77.5%) | P | Total, n=293 (100%) | Missing at baseline, n (%) |
| mRSS (0–51) | 19 (16–23) | 21 (16–27) | 0.030 | 21 (16–26) | 0 (0) |
| Months since onset of skin thickening | 8.1 (4.7–16.0) | 12.6 (8.1–22.0) | 0.001 | 12.0 (7.0–21.0) | 14 (4.8) |
| Pulmonary fibrosis, n (%) | 9 (13.6) | 31 (13.7) | 1 | 40 (13.7) | 0 (0) |
| FVC (% predicted) | 87.5 (72.0–101.0) | 91.0 (75.0–102.0) | 0.129 | 90.0 (75.0–102.0) | 16(5.5) |
| DLCO (% predicted) | 62.8 (49.0–76.5) | 66.0 (52.0–79.0) | 0.455 | 65.0 (50.0–79.0) | 31 (10.6) |
| Pulmonary hypertension, n (%) | 1 (1.5) | 19 (8.4) | 0.054† | 20 (6.8) | 1 (0.3) |
| Antitopoisomerase (anti-Scl70) (TOPO), n (%) | 30 (46.2) | 84 (38) | 0.252 | 114 (39.9) | 7 (2.4) |
| Anti-RNA polymerase III (Pol3), n (%) | 14 (25.9) | 34 (18.5) | 0.249 | 48 (20.2) | 55 (18.8) |
| Anticentromere (ACA), n (%) | 5 (7.7) | 14 (6.4) | 0.777 | 19 (6.7) | 8 (2.7) |
| No autoantibodies (TOPO, Pol3 or ACA), n (%) | 7 (12.7) | 52 (28.4) | 0.020 | 59 (24.8) | 55 (18.8) |
Median (IQR) unless otherwise indicated.
P values refer to the Kruskal-Wallis (for continuous variables) or Fisher’s test (for categorical variables).
This table compares the distribution of patient characteristics at baseline between progressors and non-progressors, using the subset of 293 for whom the progression status is known. To distinguish between non-progressors and patients with insufficient data to describe their status, data requirements were set up. If progression was not detected using all data from the first >12±3 months, patients needed at least two data points to be considered non-progressors: one at baseline and another at least 5 months after baseline. Otherwise, we considered there were not enough data to ascertain their status. The 5-month limit was chosen so that all visits in the vicinity of the 6-month study mark could be counted.
†The presence of pulmonary hypertension was not included as a variable in prediction models for progression. Only one patient had pulmonary hypertension and progressed. Thus, a prediction model using mRSS, duration of skin thickening, an mRSS/duration interaction and the presence of pulmonary hypertension was too restrictive: no combinations of mRSS and duration of skin thickening enabled patients with pulmonary hypertension to progress.
DLCO, diffusing capacity for carbon monoxide; FVC, forced vital capacity; mRSS, modified Rodnan skin score.