| Variable | 2006–2007, n = 31 676, n (%)a | 2016–2017, n = 37 393, n (%)a | March–August 2020, n = 3368, n (%)a | Total, n (%)a | |
|---|---|---|---|---|---|
| Sex | Female | 14 583 (46.0) | 17 196 (46.0) | 1591 (47.2) | 33 370 (46.1) |
| Male | 17 093 (54.0) | 20 197 (54.0) | 1777 (52.8) | 39 069 (53.9) | |
| Age, years | Mean (SD) | 67.5 (11.3) | 66.5 (11.4) | 66.4 (11.7) | 68.3 (12.0) |
| IMD quintile | 1 (least deprived) | 4692 (14.8) | 5508 (14.7) | 468 (13.9) | 10 668 (14.7) |
| 2 | 5684 (17.9) | 6544 (17.5) | 559 (16.6) | 12 787 (17.7) | |
| 3 | 5968 (18.8) | 6932 (18.5) | 648 (19.2) | 13 548 (18.7) | |
| 4 | 6683 (21.1) | 8181 (21.9) | 762 (22.6) | 15 626 (21.6) | |
| 5 (most deprived) | 8621 (27.2) | 10 208 (27.3) | 929 (27.6) | 19 758 (27.3) | |
| Missing | 28 (0.1) | 20 (0.1) | <5 (0.1) | NA (0.1) | |
| Smoking status | Missing | 776 (2.4) | 2129 (5.7) | 115 (3.4) | 3020 (4.2) |
| Never smoker | 3599 (11.4) | 3734 (10.0) | 349 (10.4) | 7682 (10.6) | |
| Ex-smoker | 12 306 (38.8) | 13 978 (37.4) | 1345 (39.9) | 27 629 (38.1) | |
| Current smoker | 14 995 (47.3) | 17 552 (46.9) | 1559 (46.3) | 34 106 (47.1) | |
| BMI measured | Yes | 28 917 (91.3) | 36 430 (97.4) | 3272 (97.1) | 68 619 (94.7) |
| No | 2759 (8.7) | 963 (2.6) | 96 (2.9) | 3818 (5.3) | |
| BMI category | Underweight (<18.5 kg/m2) | 1413 (4.5) | 1473 (3.9) | 130 (3.9) | 3016 (4.2) |
| Normal (18.5–24.9 kg/m2) | 10 905 (34.4) | 12 185 (32.6) | 1119 (33.2) | 24 209 (33.4) | |
| Overweight (25.0–29.9 kg/m2) | 9762 (30.8) | 12 223 (32.7) | 1010 (30.0) | 22 995 (31.7) | |
| Obese (≥30 kg/m2) | 6837 (21.6) | 10 549 (28.2) | 1013 (30.1) | 18 399 (25.4) | |
| Missing | 2759 (8.7) | 963 (2.6) | 96 (2.9) | 3818 (5.3) | |
| Current asthma | Yes | 8170 (25.8) | 7356 (19.7) | 672 (20.0) | 16 198 (22.4) |
| Congestive heart failure | Yes | 2008 (6.3) | 2383 (6.4) | 286 (8.5) | 4677 (6.5) |
| Total number of comorbidities | Mean (SD) | 3.5 (1.9) | 4.2 (2.1) | 4.2 (2.3) | 3.9 (2.2) |
| GOLD status | GOLD stage 1: ≥80% | 2748 (8.7) | 8516 (22.8) | 848 (25.2) | 12 112 (16.7) |
| GOLD stage 2: 50%–79% | 11 722 (37.0) | 15 839 (42.4) | 913 (27.1) | 28 474 (39.3) | |
| GOLD stage 3: 30%–49% | 4927 (15.6) | 4066 (10.9) | 217 (6.4) | 9210 (12.7) | |
| GOLD stage 4:<30% | 819 (2.6) | 502 (1.3) | 26 (0.8) | 1347 (1.9) | |
| Missing FEV1 %-predicted measurement | 11 460 (36.2) | 8470 (22.7) | 1364 (40.5) | 21 294 (29.4) |
aUnless otherwise stated. BMI = body mass index. FEV1 = forced expiratory volume. GOLD = Global Initiative for Chronic Obstructive Lung Disease. IMD = Index of Multiple Deprivation. NA = not available. SD = standard deviation.