Table 1 Summary of covariate categories
Covariate | Category id | Category description | N. Subjects |
|---|---|---|---|
Average intensity of smoking | 0 | Non-smoker | 823 |
1 | 0 < cigarettes per day ≤ 10 | 716 | |
2 | 10 < cigarettes per day ≤ 20 | 1540 | |
3 | 20 < cigarettes per day ≤ 30 | 1014 | |
4 | 30 < cigarettes per day | 550 | |
NA | Not available | 15 | |
Duration of smoking | 0 | Non-smoker | 823 |
1 | 0 < years ≤ 20 | 972 | |
2 | 20 < years ≤ 30 | 887 | |
3 | 30 < years ≤ 40 | 1073 | |
4 | 40 < years | 903 | |
Time since quit smoking | 0 | Non-smoker | 823 |
1 | 20 < years | 870 | |
2 | 10 < years ≤ 20 | 583 | |
3 | 0 < years ≤ 10 | 996 | |
4 | Current smoker | 1386 | |
Pack-years | 0 | Non-smoker | 823 |
1 | 0 < pack-years ≤ 15 | 1089 | |
2 | 15 < pack-years ≤ 30 | 1043 | |
3 | 30 < pack-years ≤ 45 | 888 | |
4 | 45 < pack-years | 800 | |
NA | Not available | 15 |