Characteristics of 109 182 patients in the PEF cohort—overall and by annual exacerbation rate (AER)
| Patient characteristics | Overall | AER 0/year | AER>0–1/year | AER>1–2/year | AER>2/year |
| (n=1 09 182) | (n=44 107) | (N=60 927) | (N=3236) | (N=912) | |
| Baseline lung function | |||||
| Median years of follow-up (IQR) | 10.4 (7.5–14.1) | 9.3 (6.9–12.8) | 11.2 (8.1–15.1) | 10.9 (7.9–14.7) | 10.6 (7.7–14.1) |
| Mean baseline % predicted PEF (SD) | 94.8 (18.6) | 95.7 (17.7) | 94.5 (19.0) | 90.9 (21.1) | 87.1 (21.2) |
| Vital statistics | |||||
| Median age at baseline (IQR) | 42 (30–55) | 39 (28–53) | 43 (32–57) | 50 (37–61) | 47 (37–60) |
| Male, N (%) | 44 697 (40.9) | 20 791 (47.1) | 22 577 (37.1) | 1007 (31.1) | 322 (35.3) |
| Median eosinophil count at baseline cells/mm3 (IQR)* | 225 (148–350) | 213 (140–335) | 230 (150–350) | 250 (156–400) | 287 (180–433) |
| Asthma status at baseline | |||||
| Median age of onset of asthma (IQR) | 35 (18–51) | 32 (16–48) | 37 (21–53) | 42 (25–56) | 39 (22–53) |
| Median years with asthma prior to index date (IQR)† | 4.5 (0.1–14.2) | 5.1 (0.1–14.7) | 4.0 (0.1–13.7) | 5.6 (0.6–15.7) | 7.1 (0.9–18.4) |
| Median number of exacerbations at baseline (IQR) | 0.2 (0.6) | 0.00 (0–0) | 0.0 (0–0) | 0.0 (0–1) | 1.0 (0–3) |
| Non-smoker, n (%) | 38 287 (35.1) | 16 637 (37.7) | 20 388 (33.5) | 983 (30.4) | 279 (30.6) |
| Ex-smoker, n (%) | 20 120 (18.4) | 7865 (17.8) | 11 436 (18.8) | 637 (19.7) | 20.0 (182) |
| Current smoker, n (%) | 16 873 (15.5) | 6381 (14.5) | 9818 (16.1) | 524 (16.2) | 150 (16.5) |
| Smoking status not recorded, n (%) | 33 902 (31.1) | 13 224 (30.0) | 19 285 (31.7) | 1092 (33.8) | 301 (33.0) |
| Median SABA prescriptions in baseline year (IQR) | 2 (1–4) | 2 (1–4) | 2 (1–5) | 3 (2–7) | 5 (2–9) |
| Median ICS dosage/day over follow-up in mcg (IQR) | 260.5 (91.8–556.96) | 161.8 (48.6379.7) | 322.7 (133.7–633.5) | 783.5 (446.4–1241.9) | 1054.7 (599.6–1586.8) |
| Median OCS prescriptions/year over follow-up (IQR) | 0.3 (0.1–0.6) | 0.1 (0.1–0.2) | 0.3 (0.1–0.5) | 2.1 (1.6–2.9) | 4.3 (3.3–5.8) |
| Asthma severity: GINA step at baseline‡ | |||||
| Step 0 (no prescriptions), n (%) | 8723 (14.69) | 8781 (19.91) | 10 665 (17.5) | 375 (11.6) | 82 (15.0) |
| Step 1 (SABA only), n (%) | 7952 (13.4) | 9760 (22.1) | 10 389 (17.1) | 280 (8.7) | 67 (7.4) |
| Step 2 (low dose ICS), n (%) | 11 675 (19.7) | 15 349 (34.8) | 19 517 (32.0) | 709 (21.9) | 121 (13.3) |
| Step 3 (low dose ICS +LABA), n (%) | 12 805 (21.7) | 7267 (16.5) | 12 912 (21.2) | 840 (26.0) | 210 (23.0) |
| Step 4 or 5 (med/high dose ICS +LABA + add ons), n (%) | 18 228 (30.7) | 2950 (6.7) | 7444 (12.2) | 1032 (31.9) | 432 (47.4) |
*Most recent eosinophil reading within 5 years of baseline and up to second year of follow-up.
†See online supplemental appendix 2 for more information on calculation of age of onset of asthma.
‡GINA step: Based on 2018 guidelines for stepped therapy for asthma (GINA).48
BMI, body mass index; GINA, Global Initiative for Asthma; ICS, inhaled corticosteroid; OCS, oral corticosteroid; PEF, peak expiratory flow rate; SABA, short-acting β2 agonist.