Characteristics of tobacco use among former cigarette smokers in Cancer Prevention Study-II who quit using tobacco entirely (“quit entirely”) or those who substituted spit tobacco for cigarettes (“switchers”)*
| Characteristics | Quit entirely | Switcher | Years between cessation and ST use | ||
|---|---|---|---|---|---|
| <1 | 1–2 | >2 | |||
| CPS-II, Cancer Prevention Study-II; IQR, interquartile range; NA, not applicable. | |||||
| *On the basis of the subgroup of 44 389 men who reported being former smokers at enrolment in CPS-II in 1982 and were also among the 86 404 men enrolled in the subsequent CPS-II Nutrition Cohort in 1992–3. | |||||
| Age started smoking (years) | |||||
| Mean | 18.4 | 17.3 | 17.0 | 17.5 | 17.6 |
| Median (IQR) | 18 (16–20) | 17 (15–19) | 16 (15–18) | 17 (15–19) | 17 (15–20) |
| Age quit smoking (years) | |||||
| Mean | 41.6 | 42.9 | 45.7 | 44.9 | 39.3 |
| Median (IQR) | 41 (33–50) | 43 (35–50) | 45 (39–54) | 45 (36–53) | 40 (31–47) |
| Age started ST use (years) | |||||
| Mean | NA | 47.3 | 45.7 | 46.3 | 49.3 |
| Median (IQR) | 48 (40–55) | 45 (39–54) | 46 (38–54) | 50 (42–56) | |
| Years between age quit smoking and age started spit tobacco use (years) | |||||
| Mean | NA | 4.3 | 0 | 1.4 | 10.1 |
| Median (IQR) | 1 (0–6) | 0 | 1 (1–2) | 8 (5–14) | |
| Cigarettes formerly smoked/day | |||||
| Mean | 25.6 | 25.5 | 26.5 | 26.1 | 24.1 |
| Median (IQR) | 20 (20–35) | 20 (20–30) | 20 (20–40) | 20 (20–40) | 20 (20–30) |
| Years smoked | |||||
| Mean | 23.2 | 25.8 | 28.8 | 27.3 | 22.0 |
| Median (IQR) | 22 (14–31) | 25 (17–34) | 29 (20–37) | 28 (18–37) | 21 (13–30) |
| Type of ST used | |||||
| Use chewing tobacco (%) | NA | 82 | 78 | 80 | 85 |
| Use snuff (%) | NA | 27 | 32 | 28 | 22 |
| Times used ST/week | |||||
| Mean | NA | 13.2 | 14.0 | 13.6 | 12.1 |
| Median (IQR) | 7 (7–15) | 7 (7–20) | 7 (7–15) | 7 (7–14) | |
| Years used ST | |||||
| Mean | na | 9.2 | 11.0 | 9.6 | 7.1 |
| Median (IQR) | 7 (3–12) | 9 (5–15) | 7 (3–13) | 5 (3–10) | |
| Reported current smoking in 1992* | |||||
| (%) | 1.4 | 3.0 | 4.0 | 1.2 | 2.7 |