Patient demographics by US or Canadian cohort
| Patient characteristics | US cohort | Canadian cohort |
| Subjects n | 477 | 122 |
| Age at diagnosis years, median (IQR) | 49 (42–56) | 52 (45–60) |
| Year of diagnosis, median (IQR) | 2010 (2006–2013) | 2016 (2013–2017) |
| Male sex, n (%) | 207 (43) | 67 (55) |
| Self-reported race, n (%) | ||
| White | 353 (74) | 112 (92) |
| Black | 110 (23) | 3 (2) |
| Asian | 1 (0.2) | 4 (3) |
| Indigenous# | 1 (0.2) | 1 (1) |
| Unknown | 12 (3) | 2 (2) |
| Smoking history, n (%) | ||
| Never | 256 (54) | 61 (50) |
| Former | 158 (33) | 51 (42) |
| Current | 35 (7) | 10 (8) |
| Unknown | 28 (6) | 0 (0) |
| Extrapulmonary manifestations at initial visit, n (%) | 238 (50) | 49 (40) |
| Skin | 109 (23) | 11 (9) |
| Liver | 27 (6) | 8 (7) |
| Spleen | 6 (1) | 2 (2) |
| Eyes | 59 (12) | 14 (11) |
| ENT | 14 (3) | 2 (2) |
| Salivary glands | 9 (2) | 3 (2) |
| Bones or joints | 35 (7) | 9 (7) |
| Bone marrow | 5 (1) | 0 (0) |
| Calcium–vitamin D homeostasis | 22 (5) | 4 (3) |
| Muscle | 3 (0.6) | 1 (0.8) |
| Extrathoracic lymphadenopathy | 12 (3) | 5 (4) |
| Renal | 2 (0.4) | 1 (0.8) |
| Central nervous system | 42 (9) | 4 (3) |
| Cardiac | 23 (5) | 10 (8) |
| Other (gastrointestinal, genitourinary, etc.) | 9 (2) | 3 (2) |
| Immunosuppressant treatment prior to initial visit, n (%) | 225 (47) | 73 (60) |
| Corticosteroid (p.o. or i.v.) | 194 (41) | 72 (59) |
| Non-biologic steroid-sparing immunosuppressant | 106 (22) | 20 (16) |
| Biologic steroid-sparing immunosuppressant | 14 (3) | 1 (1) |
| ADI or CIMD, median score (IQR) | 67 (48–83) | −0.13 (−0.49–0.24) |
| Baseline FVC % pred, median (IQR)¶ | 83 (69–95) | 87 (73–96) |
| Baseline DLCO % pred, median (IQR)+ | 75 (60–90) | 81 (73–93) |
| Follow-up duration years, median (IQR) | 8.3 (4.6–12.3) | 4.1 (2.6–7.4) |
| Final outcome, n (%) | ||
| Death | 51 (11) | 4 (3) |
| Lung transplantation | 15 (3) | 0 (0) |
| Lost to follow-up§ | 108 (23) | 2 (2) |
| Censored | 303 (63) | 95 (95) |
IQR: interquartile range; ENT: ear, nose and throat; ADI: area deprivation index; CIMD: Canadian Index of Multiple Deprivation; FVC: forced vital capacity; DLCO: diffusing capacity of the lung for carbon monoxide. #: includes Native American, American Indian, Alaskan First Nations and other Indigenous persons in the US, and First Nations, Métis, Inuit and other Indigenous persons in Canada; ¶: FVC was available for 82% of patients in the US cohort and 84% in the Canadian cohort; +: DLCO was available for 79% of patients in the US cohort and 71% in the Canadian cohort; §: patients were considered “lost to follow-up” if they were not seen within 1 year of the censoring date for this study at their following specialist centre.