Standardised mortality ratios stratified by severity of disease (ever smokers)
| Smokers (n = 447) | ||||
| No | Observed deaths | Expected deaths | SMR (95% CI) | |
| Normal | 54 | 8 | 1.01 | 7.91 (3.42 to 15.61) |
| Breathless up hill | 159 | 17 | 1.95 | 8.73 (5.08 to 13.96) |
| Breathless on level | 98 | 8 | 1.16 | 6.90 (2.98 to 13.59) |
| Breathless walking slowly | 106 | 9 | 1.00 | 9.01 (4.12 to 17.08) |
| Breathless at rest | 30 | 2 | 0.16 | 12.69 (1.51 to 45.15) |
SMR, standardised mortality ratio.