Unadjusted HR (95% CI) | p-value | AHR (95% CI) | p-value | |
Exposure | ||||
SABA canisters per year | ||||
0 | 1.23 (1.16–1.29) | <0.0001 | 1.07 (0.98–1.17) | 0.15 |
1–2 | 1.00 | (Reference) | 1.00 | (Reference) |
3–5 | 1.14 (1.05–1.25) | 0.00 | 1.11 (1.02–1.22) | 0.02 |
≥6 | 1.52 (1.38–1.67) | <0.0001 | 1.56 (1.41–1.71) | <0.0001 |
Covariate | ||||
Deprivation quintile | ||||
1 (least) | 1.00 | (Reference) | 1.00 | (Reference) |
2 | 1.09 (1.01–1.17) | 0.02 | 1.03 (0.95–1.11) | 0.47 |
3 | 1.12 (1.04–1.21) | 0.00 | 1.00 (0.93–1.08) | 0.97 |
4 | 1.21 (1.13–1.3) | <0.0001 | 1.03 (0.96–1.11) | 0.44 |
5 (most) | 1.33 (1.23–1.42) | <0.0001 | 1.11 (1.04–1.19) | 0.00 |
Dependency quintile | ||||
1 (least) | 1.00 | (Reference) | 1.00 | (Reference) |
2 | 1.10 (1.01–1.20) | 0.02 | 1.03 (0.95–1.12) | 0.52 |
3 | 1.15 (1.06–1.25) | 0.00 | 1.08 (0.99–1.17) | 0.07 |
4 | 1.30 (1.20–1.41) | <0.0001 | 1.16 (1.07–1.26) | 0.00 |
5 (most) | 1.67 (1.56–1.8) | <0.0001 | 1.25 (1.16–1.34) | <0.0001 |
Age group at index date | 1.17 (1.16–1.17) | <0.0001 | 1.16 (1.16–1.17) | <0.0001 |
Male sex (reference=female) | 1.09 (1.04–1.14) | 0.00 | 1.30 (1.24–1.36) | <0.0001 |
Rural residence (reference=urban) | 1.05 (0.97–1.13) | 0.24 | 1.19 (1.10–1.28) | <0.0001 |
ICS only or ICS-LABA | 1.00 | (Reference) | 1.00 | (Reference) |
No asthma medication | 1.43 (1.35–1.51) | <0.0001 | 1.26 (1.18–1.34) | <0.0001 |
SABA only | 1.29 (1.20–1.39) | <0.0001 | 1.19 (1.08–1.31) | 0.00 |
Other asthma medication | 1.26 (1.19–1.35) | <0.0001 | 1.16 (1.07–1.26) | 0.00 |
Asthma exacerbation in baseline period | 0.90 (0.69–1.16) | 0.40 | 1.08 (0.83–1.39) | 0.58 |
Number of comorbidities | ||||
0 | 1.00 | (Reference) | 1.00 | (Reference) |
1 | 1.63 (1.51–1.76) | <0.0001 | 1.25 (1.15–1.34) | <0.0001 |
2 | 2.54 (2.36–2.75) | <0.0001 | 1.66 (1.54–1.79) | <0.0001 |
≥3 | 3.75 (3.46–4.06) | <0.0001 | 2.13 (1.96–2.31) | <0.0001 |
AHR: adjusted hazard ratio; SABA: short-acting β2-agonist; ICS: inhaled corticosteroid; ICS-LABA: ICS long-acting β2-agonist.