Baseline demographics of patients with interstitial lung disease (ILD)
| Combined | ANA-seropositive | ANA-seronegative | p-value# | |
| Age years | 64.7±12.3 | 64.1±12.4 | 65.5±12.1 | 0.045 |
| Male | 622 (49.2) | 362 (58.2) | 260 (41.8) | 0.789 |
| BMI kg·m−2 | 29.8±6.6 | 29.6±6.7 | 30.1±6.5 | 0.251 |
| Race/ethnicity | ||||
| Caucasian | 918 (72.6) | 515 (56.1) | 403 (43.9) | 0.004 |
| African American | 203 (16.0) | 147 (72.4) | 56 (27.6) | <0.001 |
| Hispanic | 65 (5.1) | 50 (76.9) | 15 (23.1) | 0.002 |
| Asian | 47 (3.7) | 25 (53.1) | 22 (46.8) | 0.445 |
| Other | 32 (2.5) | 4 (12.5) | 28 (87.5) | <0.001 |
| Lung function | ||||
| TLC % | 71.3±18.6 | 69.0±17.2 | 74.8±20.0 | <0.001 |
| FVC % | 66.3±19.0 | 64.1±18.4 | 69.5±19.4 | <0.001 |
| DLCO % | 51.0±21.7 | 50.0±21.8 | 52.5±21.6 | 0.065 |
| ILD subtype | ||||
| IPF | 402 (31.8) | 212 (52.7) | 190 (47.3) | 0.003 |
| IPAF | 177 (14.0) | 141 (79.7) | 36 (20.3) | <0.001 |
| CTD-ILD | 240 (19.0) | 177 (73.8) | 63 (26.3) | <0.001 |
| HP | 141 (11.2) | 82 (58.2) | 59 (41.8) | 0.914 |
| Other ILD¶ | 96 (7.5) | 29 (30.2) | 67 (69.8) | <0.001 |
| Unclassifiable ILD | 209 (16.5) | 100 (47.8) | 109 (52.2) | 0.001 |
Data are presented as mean±sd or n (%), unless otherwise stated. Exception for participants: age n=1265, gender n=1265, antinuclear antibody (ANA) serologies n=1265, body mass index (BMI) n=1122, total lung capacity (TLC) n=989, forced vital capacity (FVC) n=1162, diffusing capacity of the lung for carbon monoxide (DLCO) n=1115, other ILD n=95. IPF: idiopathic pulmonary fibrosis; IPAF: interstitial pneumonia with autoimmune features; CTD-ILD: connective tissue disease associated ILD; HP: hypersensitivity pneumonitis. #: based on univariate analysis for categorical variables, e.g. Caucasian compared to non-Caucasian, IPF compared to non-IPF, etc; p-value based on two-tailed t-test for continuous variables, e.g. age, BMI; ¶: include pneumoconiosis, lymphocytic interstitial pneumonia, Langerhans cell histiocytosis, cryptogenic organising pneumonia, lymphangioleiomyomatosis and other less common ILDs with small sample sizes.