Table 1.
Baseline characteristics
| Characteristic | Children (N = 2512) | Adolescents (N = 1511) | Adults (N = 13 434) |
|---|---|---|---|
| Age, years, median (IQR) | 8.9 (7.5–10.3) | 14.5 (13.2–16.0) | 48.9 (33.9–63.9) |
|
| |||
| Sex, female, n (%) | 893 (35.5) | 747 (49.4) | 9624 (71.6) |
|
| |||
| Ethnicity, n (%) | |||
| White | 1323 (52.7) | 717 (47.5) | 8893 (66.2) |
| Black | 215 (8.6) | 105 (6.9) | 556 (4.1) |
| Mixed | 136 (5.4) | 79 (5.2) | 265 (2.0) |
| Asian | 403 (16.0) | 200 (13.2) | 1375 (10.2) |
| Other | 57 (2.3) | 23 (1.5) | 167 (1.2) |
| Missing | 378 (15.0) | 387 (25.6) | 2178 (16.2) |
|
| |||
| Index of Multiple Deprivation quintile, n (%) | |||
| 1 (least deprived) | 369 (14.7) | 210 (13.9) | 2044 (15.2) |
| 2 | 355 (14.1) | 208 (13.8) | 2207 (16.4) |
| 3 | 400 (15.9) | 263 (17.4) | 2435 (18.1) |
| 4 | 555 (22.1) | 336 (22.2) | 3059 (22.8) |
| 5 (most deprived) | 831 (33.1) | 494 (32.7) | 3681 (27.4) |
| Missing | 2 (0.1) | 0 (0) | 8 (0.1) |
|
| |||
| Body mass index, n (%) | |||
| Underweight | 186 (7.4) | 203 (13.4) | 299 (2.2) |
| Normal weight | 1008 (40.1) | 633 (41.9) | 3172 (23.6) |
| Overweight | 245 (9.8) | 215 (14.2) | 3587 (26.7) |
| Obesity | 122 (4.9) | 139 (9.2) | 5593 (41.6) |
| Missing | 951 (37.9) | 321 (21.2) | 783 (5.8) |
|
| |||
| Smoking status, n (%) | |||
| Current smoker | — | 176 (11.6) | 4093 (30.5) |
| Former smoker | — | 193 (12.8) | 5296 (39.4) |
| Never smoked | — | 921 (61.0) | 3818 (28.4) |
| Missing | — | 221 (14.6) | 227 (1.7) |
|
| |||
| Comorbidities, n (%) | |||
| Allergies | 714 (28.4) | 605 (40.0) | 4505 (33.5) |
| Atopic eczema | 1392 (55.4) | 871 (57.6) | 4205 (31.3) |
| Allergic rhinitis | 529 (21.1) | 569 (37.7) | 4344 (32.3) |
| Gastro-oesophageal reflux disease | 162 (6.4) | 76 (5.0) | 2328 (17.3) |
| Chronic rhinosinusitis | 0 (0) | 3 (0.2) | 425 (3.2) |
| Anxiety | 20 (0.8) | 104 (6.9) | 4407 (32.8) |
| Depression | 22 (0.9) | 59 (3.9) | 6432 (47.9) |
|
| |||
| Medication use within previous year, n (%) | |||
| Short-acting beta 2 agonist | |||
| 0 prescriptions | 323 (12.9) | 227 (15.0) | 3022 (22.5) |
| 1–3 prescriptions | 1055 (42.0) | 488 (32.3) | 4213 (31.4) |
| 4–6 prescriptions | 604 (24.0) | 316 (20.9) | 2530 (18.8) |
| ≥7 prescriptions | 530 (21.1) | 480 (31.8) | 3669 (27.3) |
| Oral corticosteroid | 990 (39.4) | 565 (37.4) | 7018 (52.2) |
| Inhaled corticosteroid | 1973 (78.5) | 1193 (79.0) | 10 382 (77.3) |
| Long-acting beta 2 agonist | 55 (2.2) | 78 (5.2) | 2760 (20.5) |
| Long-acting muscarinic antagonist | 0 (0) | 7 (0.5) | 1206 (9.0) |
| Leukotriene receptor antagonist | 804 (32.0) | 482 (31.9) | 2608 (19.4) |
| Flu vaccine | 1025 (40.8) | 564 (37.3) | 6920 (51.5) |
|
| |||
| Hospital admissions, n (%) | |||
| 0 | 2254 (89.7) | 1385 (91.7) | 12 865 (95.8) |
| 1–3 | 237 (9.4) | 98 (6.5) | 469 (3.5) |
| 4–6 | 14 (0.6) | 7 (0.5) | 41 (0.3) |
| ≥7 | 7 (0.3) | 21 (1.4) | 59 (0.4) |
IQR = interquartile range.