Main characteristics at baseline comparing those excluded from study population with those included, by sex
| Study population# | Excluded but asthma free at S1¶ | p-value+ | ||||
| Male | Female | Male | Female | Male | Female | |
| Overall | 2500 (48.8) | 2628 (51.3) | 1915 (49.5) | 1951 (50.5) | 0.46 | |
| Age years | <0.001 | <0.001 | ||||
| <30 | 565 (22.6) | 520 (19.8) | 399 (20.8) | 368 (18.9) | ||
| 30–40 | 629 (25.2) | 715 (27.2) | 409 (21.4) | 446 (22.9) | ||
| 40–50 | 754 (30.2) | 759 (28.9) | 533 (27.8) | 555 (28.5) | ||
| 50–60 | 497 (19.9) | 565 (21.5) | 485 (25.3) | 486 (24.9) | ||
| 60–70 | 55 (2.2) | 69 (2.6) | 89 (4.7) | 96 (4.9) | ||
| ≥70 | ||||||
| Allergic sensitisation | 849 (34.0) | 777 (29.6) | 552 (36.6) | 372 (27.3) | 0.09 | 0.13 |
| Smoking status | <0.001 | <0.001 | ||||
| Never-smoker | 1001 (40.1) | 1456 (55.4) | 569 (29.8) | 912 (46.8) | ||
| Former smoker | 649 (26.0) | 519 (19.8) | 481 (25.2) | 366 (18.8) | ||
| Current smoker | 848 (34.0) | 653 (24.9) | 862 (45.1) | 672 (34.5) | ||
| BMI kg·m−2 | 24.61±3.12 | 22.77±3.68 | 25.09±3.63 | 23.56±4.54 | <0.001 | <0.001 |
| Parental asthma | 205 (8.2) | 298 (11.3) | 173 (9.1) | 196 (10.1) | 0.33 | 0.18 |
| Early-life respiratory infection | 146 (5.8) | 215 (8.2) | 100 (5.2) | 144 (7.4) | 0.39 | 0.35 |
| Occupational exposure | 1005 (40.2) | 530 (20.2) | 849 (44.5) | 459 (23.8) | 0.01 | 0.00 |
| Education | <0.001 | <0.001 | ||||
| Low | 223 (8.9) | 404 (15.4) | 391 (20.5) | 493 (25.4) | ||
| Intermediate | 1647 (65.9) | 1923 (73.2) | 1129 (59.2) | 1274 (65.6) | ||
| High | 630 (25.2) | 300 (11.4) | 388 (20.3) | 174 (9.0) | ||
Data are presented as n (%) or mean±sd, unless otherwise stated. S: Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA); BMI: body mass index. #: n=5128; reporting no doctor-diagnosed asthma at baseline, providing complete information on doctor-diagnosed asthma in at least S1 and S3 and having complete covariate information. ¶: n=3866; having incomplete asthma information in S1/S3, having missing covariate information, not participating in S3, but being asthma free at S1 in 1991. +: using t-test for variables sex, age and BMI, and Fisher exact test for variables smoking, parental asthma, early-life respiratory infection, education, allergic sensitisation and occupational exposure.