Demographic characteristics of 6920 pigeon breeders and their 276 800 individually matched referents 1980–2013
| Pigeon breeders | Referents | |
| Sex | ||
| Female | 451 (6.5) | 18 040 (6.5) |
| Male | 6469 (93.5) | 258 760 (93.5) |
| Year of birth | ||
| <1930 | 1881 (27.2) | 75 240 (27.2) |
| 1930–1949 | 2578 (37.2) | 103 120 (37.2) |
| 1950–1969 | 1466 (21.2) | 58 640 (21.2) |
| 1970–1989 | 680 (9.8) | 27 200 (9.8) |
| >1989 | 315 (4.6) | 12 600 (4.6) |
| Start of follow-up | ||
| 1980–1989 | 3282 (47.4) | 131 280 (47.4) |
| 1990–1999 | 150 (2.2) | 6000 (2.2) |
| 2000–2009 | 3301 (47.7) | 132 040 (47.7) |
| >2009 | 187 (2.7) | 7480 (2.7) |
| Censoring during follow-up | ||
| Connective tissue disease | 144 (2.1) | 5416 (2.0) |
| Emigration | 110 (1.6) | 9518 (3.4) |
| Death | 2535 (36.6) | 98 529 (35.6) |
| Not censored | 4131 (59.7) | 163 337 (59.0) |
| Occupation at start of follow-up | ||
| White-collar worker | 1780 (25.7) | 102 059 (36.9) |
| Blue-collar worker | 3942 (57.0) | 127 091 (45.9) |
| Pensioner | 660 (9.5) | 25 925 (9.4) |
| Student | 278 (4.0) | 10 610 (3.8) |
| Unclassified worker | 260 (3.8) | 11 115 (4.0) |
| Residence at start of follow-up | ||
| City | 2269 (32.8) | 119 246 (43.1) |
| Urban | 1084 (15.7) | 40 836 (14.8) |
| Rural | 2385 (34.4) | 76 223 (27.5) |
| Isolated | 803 (11.6) | 25 996 (9.4) |
| Unknown | 379 (5.5) | 14 499 (5.2) |
| Redeemed prescription of medication with ILD as possible side-effect before or during follow-up | ||
| Yes | 475 (6.9) | 18 740 (6.8) |
| No | 6445 (93.1) | 258 060 (93.2) |
| Total | 6920 (100.0) | 276 800 (100.0) |
Data are presented as n (%). ILD: interstitial lung disease.