Study population demographic and clinical characteristics at baseline
| Exposeda cohort | Unexposedb cohort | P-valuec | |
|---|---|---|---|
| Patients, nd | 75 698 | 75 698 | — |
| Year of index date, median (IQR)d | 2005 (2001–2007) | 2005 (2001–2007) | — |
| Age, years, n (%)d | — | ||
| 18–44 | 16 668 (22.0) | 16 668 (22.0) | |
| 45–59 | 20 356 (26.9) | 20 356 (26.9) | |
| 60–74 | 23 813 (31.5) | 23 813 (31.5) | |
| ≥75 | 14 861 (19.6) | 14 861 (19.6) | |
| Male, n (%)d | 32 195 (42.5) | 32 195 (42.5) | — |
| Geographical region, n (%)d | — | ||
| London | 6154 (8.1) | 6154 (8.1) | |
| South of England | 19 592 (25.9) | 19 592 (25.9) | |
| Midlands and East of England | 24 219 (32.0) | 24 219 (32.0) | |
| North of England | 25 733 (34.0) | 25 733 (34.0) | |
| Smoking status, n (%) | <0.001 | ||
| Non-smoker | 40 436 (53.4) | 42 632 (56.3) | |
| Smoker, ever | 24 740 (32.7) | 19 143 (25.3) | |
| Unknown | 10 522 (13.9) | 13 923 (18.4) | |
| Alcohol consumption, n (%) | <0.001 | ||
| Non-drinker | 8623 (11.4) | 7425 (9.8) | |
| Drinker, ever | 54 991 (72.7) | 52 197 (69.0) | |
| Unknown | 12 084 (16.0) | 16 076 (21.2) | |
| BMI, n (%) | <0.001 | ||
| <25 kg/m2 | 23 901 (31.6) | 27 054 (35.7) | |
| ≥ 25 kg/m2 | 39 854 (52.6) | 32 194 (42.5) | |
| Unknown | 11 943 (15.8) | 16 450 (21.7) | |
| Deprivation-level quintile, n (%) | <0.001 | ||
| 1 (least) | 17 008 (22.5) | 18 231 (24.1) | |
| 2 | 18 123 (23.9) | 19 043 (25.2) | |
| 3 | 15 810 (20.9) | 15 644 (20.7) | |
| 4 | 13 508 (17.8) | 12 772 (16.9) | |
| 5 (most) | 11 163 (14.7) | 9929 (13.1) | |
| Unknown | 86 (0.1) | 79 (0.1) | |
| Number of comorbidities, median (IQR) | 6 (3–11) | 3 (1–7) | <0.001 |
↵a Patients with recorded breathlessness.
↵b Patients without recorded breathlessness.
↵c P-value obtained from χ2 or from Mann–Whitney U test as appropriate, and, where applicable, analysis excluded unknown category (missing data).
↵d Unexposed cohort matched. BMI = body mass index. IQR = interquartile range.