Exacerbations by patient’s BTS step and age cohort
| Under 5s | 5 to 17s | 18 to 54s | 55+ | Mean population rate per BTS step | |||||
| N (% of BTS) | Rate (95% CI) | N (% of BTS) | Rate (95% CI) | N (% of BTS) | Rate (95% CI) | N (% of BTS) | Rate (95% CI) | ||
| BTS 1 | 656 (13.4) | 2.01 (1.89 to 2.14) | 4849 (14.6) | 0.73 (0.70 to 0.77) | 26 607 (30.8) | 1.82 (1.78 to 1.86) | 11 805 (47.3) | 5.01 (4.84 to 5.20) | 2.39 (2.30–2.49) |
| BTS 2 | 1439 (21.0) | 4.12 (3.98 to 4.29) | 5958 (22.3) | 1.41 (1.36 to 1.46) | 19 704 (36.0) | 2.79 (2.74 to 2.85) | 14 041 (57.2) | 6.60 (6.41 to 6.80) | 3.73 (3.62–3.85) |
| BTS 3 | 343 (35.0) | 8.57 (8.01 to 9.17) | 1141 (30.1) | 2.51 (2.30 to 2.76) | 8003 (42.9) | 3.88 (3.75 to 4.01) | 8155 (66.2) | 8.53 (8.26 to 8.82) | 5.87 (5.58–6.19) |
| BTS 4 | 663 (29.8) | 7.52 (7.16 to 7.91) | 4028 (34.2) | 2.53 (2.41 to 2.66) | 15 362 (46.8) | 5.16 (5.03 to 5.29) | 17 638 (68.6) | 10.83 (10.59 to 11.08) | 6.51 (6.30–6.74) |
| BTS 5 | 35 (36.1) | 10.59 (8.59 to 13.05) | 508 (44.3) | 5.18 (4.57 to 5.88) | 8494 (57.9) | 8.07 (7.84 to 8.31) | 14 575 (75.0) | 13.27 (13.00 to 13.55) | 9.28 (8.50–10.20) |
| BTS 6 | <5 (0.0) | 31.89 (13.27 to 76.6) | 21 (95.5) | 56.36 (42.40 to 77.21) | 547 (87.8) | 42.1 (39.2 to 45.4) | 1531 (94.0) | 60.19 (57.97 to 62.52) | 47.64 (38.21–65.43) |
| Non-BTS | 131 (27.3) | 5.58 (4.96 to 6.28) | 649 (32.1) | 3.11 (2.75 to 3.52) | 1211 (47.6) | 6.90 (6.32 to 7.55) | 2986 (64.7) | 12.07 (11.43 to 12.75) | 6.92 (6.37–7.53) |
N is the total number of patients who exacerbated, per cent of patients with exacerbations in that BTS category in that cohort; rates are per 10 person-years.
BTS, British Thoracic Society.