Characteristics of unclassifiable interstitial lung disease patients
| Country | Years | Unclassifiable n/total N (%) | With surgical biopsy % | Male % | Age years | FVC % | DLCO % |
| Spain | 1995–2004 | 73/500 (14.6) | 26.2 | 47 | 66.7±13.6 | ||
| China | 1999–2009 | 38/251 (15.1) | 100 | ||||
| Spain | 2000–2001 | 26/511 (5.1) | 22.7 | ||||
| USA | 2000–2011 | 132/1370 (9.6) | 31 | 53 | 67.8±12.9 | 69.0±22.1 | 47.6±19.7 |
| Denmark | 2003–2009 | 62/431 (14) | 34 | 45 | 59.3±14.5 | 73.7±22.8 | 55.8±21.4 |
| Australia | 2011–2013 | 23/232 (9.9) |
Data are presented as mean±sd, unless otherwise stated. Blank cells represent data that were not reported. FVC: forced vital capacity; DLCO: diffusing capacity of the lung for carbon monoxide. Reproduced and modified from [39] with permission.