Table 1.
Baseline characteristics of the study population by phenotype
| Benign asthma | Atopic asthma | Obese non-eosinophilic | NOS no medication | NOS with only SABA | NOS with maintenance | Total | |
|---|---|---|---|---|---|---|---|
|
| |||||||
| Total | 7,495 | 55,455 | 9,372 | 20,204 | 11,926 | 89,547 | 193,999 (100.0%) |
| Percentage of total | 3.9% | 28.6% | 4.8% | 10.4% | 6.1% | 46.2% | 100.0% |
| Follow-up median and IQR | 4.28 (2.05–6.36) | 4.34 (2.10–6.46) | 4.54 (2.21–6.84) | 3.46 (1.41–5.26) | 4.11 (1.93–6.11) | 4.35 (2.10–6.46) | 4.24 (1.99–6.34) |
| Gender | |||||||
| Female | 4,727 (63.1%) | 38,060 (68.6%) | 9,372 (100.0%) | 13,627 (67.4%) | 7,142 (59.9%) | 53,828 (60.1%) | 126,756 (65.3%) |
| Age category (years) | |||||||
| 18–30 | 0 | 10,693 (19.3%) | 813 (8.7%) | 6,536 (32.4%) | 1,966 (16.5%) | 9,600 (10.7%) | 29,608 (15.3%) |
| 31–50 | 4,201 (56.1%) | 19,762 (35.6%) | 3,127 (33.4%) | 6,810 (33.7%) | 4,736 (39.7%) | 26,585 (29.7%) | 65,221 (33.6%) |
| 51–70 | 3,294 (43.9%) | 17,005 (30.7%) | 3,888 (41.5%) | 4,365 (21.6%) | 3,451 (28.9%) | 32,381 (36.2%) | 64,384 (33.2%) |
| ≥71 | 0 | 7,995 (14.4%) | 1,544 (16.5%) | 2,493 (12.3%) | 1,773 (14.9%) | 20,981 (23.4%) | 34,786 (17.9%) |
| Socioeconomic status | |||||||
| 1: least deprived | 2,092 (27.9%) | 13,647 (24.6%) | 1,260 (13.4%) | 4,696 (23.2%) | 2,465 (20.7%) | 17,971 (20.1%) | 42,131 (21.7%) |
| 2 | 1,724 (23.0%) | 12,153 (21.9%) | 1,644 (17.5%) | 4,306 (21.3%) | 2,405 (20.2%) | 18,813 (21.0%) | 41,045 (21.2%) |
| 3 | 1,513 (20.2%) | 11,090 (20.0%) | 1,801 (19.2%) | 4,154 (20.6%) | 2,450 (20.5%) | 18,352 (20.5%) | 39,360 (20.3%) |
| 4 | 1,219 (16.3%) | 10,189 (18.4%) | 2,149 (22.9%) | 3,844 (19.0%) | 2,423 (20.3%) | 17,655 (19.7%) | 37,479 (19.3%) |
| 5: most deprived | 943 (12.6%) | 8,350 (15.1%) | 2,513 (26.8%) | 3,192 (15.8%) | 2,180 (18.3%) | 16,702 (18.7%) | 33,880 (17.5%) |
| Smoking status | |||||||
| Current smoker | 1,473 (19.7%) | 10,523 (19.0%) | 2,485 (26.5%) | 4,637 (23.0%) | 3,541 (29.7%) | 22,165 (24.8%) | 44,824 (23.1%) |
| Ex-smoker | 2,884 (38.5%) | 22,930 (41.3%) | 3,813 (40.7%) | 6,679 (33.1%) | 4,090 (34.3%) | 38,000 (42.4%) | 78,396 (40.4%) |
| Never smoker | 3,138 (41.9%) | 22,002 (39.7%) | 3,074 (32.8%) | 8,888 (44.0%) | 4,295 (36.0%) | 29,382 (32.8%) | 70,779 (36.5%) |
| BMI | |||||||
| <20 | 278 (3.7%) | 3,257 (5.9%) | 0 | 1,477 (7.3%) | 756 (6.3%) | 6,018 (6.7%) | 11,786 (6.1%) |
| 20–25 | 2,041 (27.2%) | 16,819 (30.3%) | 0 | 6,596 (32.6%) | 3,488 (29.2%) | 25,468 (28.4%) | 54,412 (28.0%) |
| 25–30 | 2,703 (36.1%) | 18,814 (33.9%) | 0 | 6,267 (31.0%) | 4,080 (34.2%) | 31,068 (34.7%) | 62,935 (32.4%) |
| >30 | 2,473 (33.0%) | 16,565 (29.9%) | 9,369 (100.0%) | 5,864 (29.0%) | 3,602 (30.2%) | 26,993 (30.1%) | 64,866 (33.4%) |
| BTS step | |||||||
| BTS1 | 4,401 (58.7%) | 11,612 (20.9%) | 754 (8.0%) | 20,204 (100.0%) | 11,926 (100.0%) | 0 | 48,897 (25.2%) |
| BTS2 | 1,186 (15.8%) | 18,898 (34.1%) | 2,526 (27.0%) | 0 | 0 | 29,809 (33.3%) | 52,419 (27.0%) |
| BTS3 | 520 (6.9%) | 6,220 (11.2%) | 1,164 (12.4%) | 0 | 0 | 12,309 (13.7%) | 20,213 (10.4%) |
| BTS4 | 978 (13.0%) | 11,710 (21.1%) | 2,625 (28.0%) | 0 | 0 | 26,173 (29.2%) | 41,486 (21.4%) |
| BTS5 | 263 (3.5%) | 5,346 (9.6%) | 1,831 (19.5%) | 0 | 0 | 15,825 (17.7%) | 23,265 (12.0%) |
| BTS6 | 3 (>0%) | 243 (>4%) | 129 (1.4%) | 0 | 0 | 1,457 (1.6%) | 1,832 (>9%) |
| Non BTS | 144 (1.9%) | 1,426 (2.6%) | 343 (3.7%) | 0 | 0 | 3,974 (4.4%) | 5,887 (3.0%) |
| Comorbid conditions | |||||||
| Atopy | 3,069 (40.9%) | 45,632 (82.3%) | 3,965 (42.3%) | 9,283 (45.9%) | 1,388 (11.6%) | 26,577 (29.7%) | 89,914 (46.3%) |
| GORD | 1,291 (17.2%) | 11,331 (20.4%) | 2,374 (25.3%) | 2,965 (14.7%) | 1,859 (15.6%) | 18,242 (20.4%) | 38,062 (19.6%) |
| Anxiety | 2,161 (28.8%) | 17,841 (32.2%) | 3,584 (38.2%) | 5,835 (28.9%) | 3,397 (28.5%) | 26,182 (29.2%) | 59,000 (30.4%) |
| Depression | 2,874 (38.3%) | 21,826 (39.4%) | 5,125 (54.7%) | 7,240 (35.8%) | 4,394 (36.8%) | 34,056 (38.0%) | 75,515 (38.9%) |
| COPD | 351 (4.7%) | 5,676 (10.2%) | 1,836 (19.6%) | 1,005 (5.0%) | 1,313 (11.0%) | 20,512 (22.9%) | 30,693 (15.8%) |
| Eosinophils | |||||||
| Eosinophils <300/µL and <4% | 7,495 (100.0%) | 24,967 (45.0%) | 9,372 (100.0%) | 9,800 (48.5%) | 6,439 (54.0%) | 38,539 (43.0%) | 96,612 (49.8%) |
| Eosinophils >300/µL or >4% | 0 | 30,488 (55.0%) | 0 | 10,404 (51.5%) | 5,487 (46.0%) | 51,008 (57.0%) | 97,387 (50.2%) |
| SABA | |||||||
| 0 prescriptions | 7,495 (100.0%) | 0 | 0 | 20,204 (100.0%) | 0 | 16,306 (18.2%) | 44,005 (22.7%) |
| 1–2 prescriptions | 0 | 0 | 0 | 0 | 7,430 (62.3%) | 21,671 (24.2%) | 68,381 (35.2%) |
| 3–9 prescriptions | 0 | 16,175 (29.2%) | 7,519 (80.2%) | 0 | 3,585 (30.1%) | 36,703 (41.0%) | 63,982 (33.0%) |
| 10+ prescriptions | 0 | 0 | 1,853 (19.8%) | 0 | 911 (7.6%) | 14,867 (16.6%) | 17,631 (9.1%) |
Abbreviations: BMI, body mass index; BTS, British Thoracic Society; GORD, gastro-oesophageal reflux disease; NOS, not otherwise specified; SABA, short-acting beta agonist.