Participant characteristics in the derivation (n = 58 619) and validation (n = 174 240) datasetsa
| Characteristic | Derivation dataset, n (%)b | Validation dataset, n (%)b |
|---|---|---|
| Sex | ||
| Male | 19 684 (33.58) | 78 437 (45.02) |
| Female | 38 935 (66.42) | 95 803 (54.98) |
| Age, years, mean (SD) | 49.70 (16.86) | 44.47 (22.57) |
| Outcome, derivation data: HES hospital admissions for asthma | ||
| ≥1 admission | 969 (1.65) | — |
| No admissions | 57 650 (98.35) | — |
| Outcome, validation data: asthma-related crisis event: hospital admission, A&E attendance, or death | ||
| Hospital admission | — | 1434 (0.82) |
| A&E attendance | — | 75 (0.04) |
| Death | — | 1235 (0.7) |
| ≥1 asthma events | — | 2439 (1.40)c |
| No asthma events | — | 171 801 (98.60) |
| Age group, years | ||
| 12– 60 | 40 809 (69.62) | 125 802 (72.20) |
| 61–80 | 17 810 (30.38) | 48 438 (27.80) |
| Smoking status | ||
| Current smoker | 10 498 (17.91) | 33 880 (19.44) |
| Ex-smoker | 15 564 (26.55)d | 70 544 (40.49)e |
| BMI | ||
| Underweight:<18.5 kg/m2 | 1332 (2.27) | 5160 (2.96) |
| Normal: 18.5–<25 kg/m2 | 18 403 (31.39) | 82 221 (47.19) |
| Overweight: 25–<30 kg/m2 | 19 182 (32.72) | 42 725 (24.52) |
| Obese: ≥30 kg/m2 | 19 702 (36.61) | 44 134 (25.33) |
| Count of blood eosinophils at baseline | ||
| ≤400 µl | 49 172 (83.88) | 155 922 (89.49) |
| >400 µl | 9447 (16.12) | 18 318 (10.51) |
| IHD | 3549 (6.05) | 11 120 (6.30) |
| ≥1 LTRA prescriptions | 2871 (4.90) | 11 258 (6.46) |
| Diabetes diagnosis and/or therapy | 15 210 (25.95) | 12 895 (7.40) |
| Paracetamol | 18 482 (31.53) | 28 018 (16.08) |
| Rhinitis diagnosis and/or drugs in baseline | 27 845 (47.50) | 27 127 (15.57) |
| Number of courses of acute oral steroids | ||
| 1 | 6444 (10.99) | 17 390 (9.98) |
| 2 | 2272 (3.88) | 7083 (4.07) |
| ≥3 | 2754 (4.70) | 9056 (5.20) |
| Previous hospitalisations | ||
| ≥1 | 959 (1.64) | 1057 (0.61) |
| GP consultations for LRTI | ||
| 1 | 7346 (12.53) | 20 764 (11.92) |
| ≥2 | 2550 (4.35)f | 6990 (4.01)g |
| Number of SABA prescriptions | ||
| 0–2 | 30 368 (51.81) | 73 688 (42.29) |
| 3–6 | 17 912 (30.56) | 51 725 (29.69) |
| 7–12 | 7945 (13.55) | 33 235 (19.07) |
| ≥13 | 2394 (4.08) | 15 592 (8.95) |
| Anxiety and/or depression | 24 222 (41.32) | 39 664 (22.76) |
| History of anaphylaxis | 360 (0.61) | 850 (0.49) |
| GINA management steps, regrouped | ||
| No therapy | 5180 (8.84) | 519 (0.30) |
| Step 1–2 | 31 923 (54.46) | 73 470 (42.17) |
| Step 3 | 7990 (13.63) | 85 645 (49.15) |
| Step 4–5 | 13 526 (23.07) | 14 606 (8.38) |
↵a This table contains frequencies of each variable for those individuals for whom all variables included in the algorithm were available.
↵b Unless otherwise stated.
↵c Individuals can have ≥1 event, so the total is less than the sum of the individual occurrences.
↵d Missing 32 557 were non-smokers.
↵e Missing 69 816 were non-smokers.
↵f The remaining 48 723 are ‘none’.
↵g The remaining 146 486 are ‘none’. A&E = accident and emergency. BMI = body mass index. GINA = Global Initiative for Asthma. HES = Hospital Episode Statistics. IHD = ischaemic heart disease. LRTA = leukotriene receptor antagonist. LTRI = lower respiratory tract infection. SABA = short-acting beta-agonist. SD = standard deviation.