Descriptive characteristics of the three cohorts
| Characteristic | Resolved asthma (n = 16 023) | Active asthma (n = 16 023) | Non-asthma (n = 16 023) |
|---|---|---|---|
| Sex | |||
| Male | 7303 (45.6) | 7303 (45.6) | 7303 (45.6) |
| Female | 8720 (54.4) | 8720 (54.4) | 8720 (54.4) |
| Age at start FUP, years, mean (SD) | 37.06 (20.27) | 37.41 (20.24) | 37.06 (20.27) |
| Years of follow-up, mean (SD) | 1.99 (1.86) | 3.54 (2.58) | 2.68 (2.02) |
| Index of Multiple | |||
| Deprivation quintile | |||
| 1 — most deprived | 3854 (24.1) | 3695 (23.1) | 3849 (24.0) |
| 2 | 3583 (22.4) | 3514 (21.9) | 3570 (22.3) |
| 3 | 3134 (19.6) | 3158 (19.7) | 3061 (19.1) |
| 4 | 2876 (17.9) | 2961 (18.5) | 2893 (18.1) |
| 5 — least deprived | 2576 (16.1) | 2695 (16.8) | 2650 (16.5) |
| Charlson scorea | |||
| 0 | 680 (4.2) | 531 (3.3) | 14 249 (88.9) |
| 1 | 13 425 (83.8) | 13 582 (84.8) | 770 (4.8) |
| 2 | 744 (4.6) | 728 (4.5) | 677 (4.2) |
| 3 | 752 (4.7) | 772 (4.8) | 168 (1.0) |
| 4 | 225 (1.4) | 223 (1.4) | 92 (0.6) |
| ≥5 | 197 (1.2) | 187 (1.2) | 67 (0.4) |
| Smoking status | |||
| Non-smoker | 9198 (57.4) | 9167 (57.2) | 7618 (47.5) |
| Ex-smoker | 2528 (15.8) | 2726 (17.0) | 2128 (13.3) |
| Current smoker | 2736 (17.1) | 2864 (17.9) | 2744 (17.1) |
| Missing | 1561 (9.7) | 1266 (7.9) | 3533 (22.0) |
| Spirometry recorded in observation period, yes | 880 (5.5) | 310 (1.9) | — |
| FEV1 recorded in observation period, yes | 910 (5.7) | 374 (2.3) | — |
| Annual asthma review recorded in observation period, yes | 3658 (22.8) | 11 779 (73.5) | — |
↵a Charlson score of 0 indicates no comorbidity. Values are n (%) unless otherwise indicated. FEV1 = forced expiratory volume in 1 second. FUP = follow-up. SD = standard deviation.