Table 1.
Baseline characteristics of the study population.
| VARIABLE | RA-ILD N = 35 |
RA without ILD N = 35 |
p Value |
|---|---|---|---|
| Epidemiological characteristics | |||
| Age, years, mean (SD) | 69.7 (9.3) | 66.6 (7.0) | 0.130 |
| Male sex; n (%) | 20 (57.1) | 20 (57.1) | 1.000 |
| Clinical-analytical characteristics | |||
| Smoking history | 0.760 | ||
| Nonsmokers, n (%) | 17 (48.6) | 18 (51.4) | |
| Ex-smokers, n (%) | 10 (28.6) | 8 (22.9) | |
| Active smokers, n (%) | 8 (22.9) | 9 (25.7) | |
| Time with RA, months, median (IQR) | 149.8 (93.3–245.5) | 133.7 (67.8–204.2) | 0.384 |
| Time with ILD, months, mean (SD) | 66.1 (47.2) | - | - |
| RF+ (>10), n (%) | 33 (94.3) | 31 (88.6) | 0.393 |
| High RF (>60), n (%) | 24 (68.6) | 17 (48.6) | 0.089 |
| ACPA+ (>20), n (%) | 32 (91.4) | 31 (88.6) | 0.690 |
| ACPA titer, median (IQR) | 562.0 (150.0–1305.0) | 283.0 (41.0–816.0) | 0.073 |
| High ACPA titer (>340), n (%) | 22 (63.0) | 14 (40.0) | 0.039 |
| Radiographic erosions, n (%) | 21 (60.0) | 19 (55.6) | 0.705 |
| Current treatment | |||
| csDMARD, n (%) | 28 (80.0) | 33 (94.3) | 0.074 |
| Methotrexate, n (%) | 19 (54.3) | 27 (77.1) | 0.040 |
| Leflunomide, n (%) | 3 (8.6) | 6 (17.1) | 0.284 |
| Sulfasalazine, n (%) | 2 (5.7) | 2 (5.7) | 1.000 |
| Hydroxychloroquine, n (%) | 6 (17.1) | 0 (0.0) | 0.010 |
| Mycophenolate, n (%) | 4 (11.4) | 0 (0.0) | 0.032 |
| bDMARD, n (%) | 22 (62.9) | 18 (51.4) | 0.334 |
| Anti-TNF, n (%) | 4 (11.4) | 11 (31.4) | 0.041 |
| Tocilizumab, n (%) | 3 (8.6) | 2 (5.7) | 0.643 |
| Abatacept, n (%) | 13 (37.1) | 3 (8.6) | 0.004 |
| Rituximab, n (%) | 2 (5.7) | 0 (0.0) | 0.151 |
| JAK inhibitor, n (%) | 0 (0.0) | 2 (5.7) | 0.151 |
| Corticosteroids, n (%) | 22 (62.9) | 6 (17.1) | 0.001 |
| Nintedanib, n (%) | 1 (2.9) | 0 (0.0) | 0.314 |
| Dose of corticosteroid, mg/d, mean (SD) | 7.9 (4.0) | 5.0 (0.0) | 0.135 |
| Pulmonary function tests | |||
| FVC < 80%, n (%) | 28 (80.0) | 5 (14.3) | <0.001 |
| FVC predicted (%), mean (SD) | 63.0 (17.1) | 83.4 (4.4) | <0.001 |
| FEV1 < 80%, n (%) | 23 (67.6) | 5 (14.3) | 0.001 |
| FEV1 predicted (%), mean (SD) | 68.7 (15.9) | 84.0 (11.5) | <0.001 |
| DLCO < 80%, n (%) | 29 (85.3) | 3 (8.6) | <0.001 |
| DLCO-SB predicted (%), mean (SD) | 61.0 (15.2) | 85.9 (7.9) | <0.001 |
| HRCT pattern | |||
| UIP, n (%) | 29 (82.9) | 0 (0.0) | <0.001 |
| NSIP, n (%) | 6 (17.1) | 0 (0.0) | <0.001 |
Abbreviations: RA: rheumatoid arthritis; ILD: interstitial lung disease; SD: standard deviation; RF: rheumatoid factor; ACPA: anti–citrullinated peptide antibody; csDMARD: conventional synthetic disease-modifying antirheumatic drug; bDMARD: biologic disease-modifying antirheumatic drug; FVC: forced vital capacity; FEV1: forced expiratory volume in the first second; DLCO: diffusing capacity of the lung for carbon monoxide; HRCT: high-resolution computed tomography; UIP: usual interstitial pneumonia; NSIP: nonspecific interstitial pneumonia.