Summary of the characteristics of the three interviewed samples
| Gender (M:F) | Age (years) | Pack years | Smoking status | |||
| Average | Range | Average | Range | Current:ex-smoker | ||
| Group a | 10:6 | 70 | 52–81 | 54 | 8–137 | 4:12 |
| Group b | 11:9 | 70 | 57–76 | 51 | 12–100 | 9:11 |
| Group c | 8:16 | 71 | 57–79 | 53 | 17–171 | 11:13 |
Group a: participating in the randomised controlled trial, annual sputum testing (16 respondents).
Group b: participating in the randomised controlled trial, receiving annual CT scan and bronchoscopy (20 respondents).
Group c: those who declined to take part in the randomised controlled trial (24 respondents).