Table 4.
Hazard ratios for lung cancer mortality in current smokers, by smoking exposure and education
| Mena HRs 95% CI | |||||||
|---|---|---|---|---|---|---|---|
| Education in years | |||||||
| Smoking status | Cases | < 10 years HRa 95% CI |
Cases | 10–12 years HRa 95% CI |
Cases | ≥13 years HRa 95% CI |
Heterogeneity testb P-values |
| Never smokersc | 18 | 1.00 (ref) | 54 | 1.00 (ref) | 19 | 1.00 (ref) | |
| Current smokers | 1303 | 28.96 (18.17–46.14) | 1216 | 16.01 (12.19–21.05) | 254 | 22.50 (14.09–35.92) | 0.45 |
| Duration of smoking (years) | |||||||
| 1–19 | 120 | 18.27 (11.08–30.12) | 130 | 9.13 (6.61–12.61) | 27 | 9.95 (5.49–18.03) | 0.13 |
| 20–29 | 717 | 27.93 (17.43–44.74) | 758 | 15.61 (11.80–20.66) | 151 | 23.56 (14.51–38.25) | 0.62 |
| > 30 | 465 | 32.72 (20.35–52.62) | 318 | 19.92 (14.65–27.09) | 75 | 35.32 (19.59–63.69) | 0.84 |
| P for trendd | < 0.01 | < 0.01 | < 0.01 | ||||
| Cigarettes smoked per day | |||||||
| 1–10 | 400 | 20.71 (12.91–33.23) | 262 | 8.98 (7.00–12.05) | 53 | 12.26 (7.25–20.74) | 0.15 |
| 11–20 | 684 | 34.57 (21.62–55.28) | 710 | 19.00 (14.38–25.10) | 142 | 27.96 (17.27–45.29) | 0.54 |
| > 21 | 165 | 54.57 (33.46–89.00) | 211 | 33.76 (24.96–45.65) | 49 | 50.24 (29.37–85.93) | 0.82 |
| P for trendd | < 0.01 | < 0.01 | < 0.01 | ||||
| Pack-years | |||||||
| 1–9 | 141 | 15.84 (9.68–25.92) | 101 | 6.49 (4.65–9.05) | 19 | 7.34 (3.88–13.91) | 0.06 |
| 10–19 | 497 | 25.45 (15.88–40.78) | 443 | 13.55 (10.20–18.00) | 87 | 21.18 (12.85–34.89) | 0.60 |
| ≥ 20 | 611 | 40.43 (25.28–64.65) | 632 | 23.84 (18.04–31.54) | 138 | 37.02 (22.78–60.17) | 0.80 |
| P for trendd | < 0.01 | < 0.01 | < 0.01 | ||||
|
Womena HRs 95% CI | |||||||
| Smoking status | Cases | HRa 95% CI | Cases | HRa 95% CI | Cases | HRa 95% CI | |
| Never smokers | 70 | 1.00 (ref) | 81 | 1.00 (ref) | 37 | 1.00 (ref) | |
| Current smokers | 980 | 15.85 (12.32–20.38) | 887 | 14.22 (11.28–17.92) | 116 | 9.41 (6.49–13.68) | < 0.01 |
| Duration of smoking (years) | |||||||
| 1–19 | 155 | 8.37 (6.21–11.29) | 158 | 7.62 (5.78–10.06) | 20 | 3.83 (2.20–6.65) | 0.01 |
| 20–29 | 624 | 16.11 (12.32–21.08) | 603 | 16.19 (12.70–20.63) | 73 | 11.01 (7.35–16.48) | 0.12 |
| > 30 | 194 | 23.05 (17.16–30.97) | 120 | 21.85 (15.79–30.25) | 22 | 27.18 (13.30–55.52) | 0.68 |
| P for trendd | < 0.01 | < 0.01 | < 0.01 | ||||
| Cigarettes smoked per day | |||||||
| 1–10 | 458 | 12.81 (9.87–16.62) | 326 | 9.43 (7.37–12.07) | 36 | 5.15 (3.26–8.20) | < 0.01 |
| 11–20 | 465 | 22.88 (17.50–29.92) | 500 | 21.35 (16.75–27.22) | 78 | 14.47 (9.66–21.69) | 0.06 |
| > 21 | 54 | 41.62 (28.75–60.25) | 57 | 39.87 (28.22–56.34) | 8 | 19.70 (9.04–42.97) | 0.09 |
| P for trendd | < 0.01 | < 0.01 | < 0.01 | ||||
| Pack-years | |||||||
| 1–9 | 197 | 8.31 (6.27–11.02) | 148 | 6.08 (4.61–8.01) | 18 | 3.31 (1.88–5.84) | < 0.01 |
| 10–19 | 481 | 18.27 (14.05–23.77) | 457 | 16.95 (13.31–21.60) | 57 | 12.00 (7.89–18.25) | 0.10 |
| ≥ 20 | 294 | 29.66 (22.60–38.93) | 274 | 27.92 (21.66–35.98) | 39 | 18.49 (11.68–29.26) | 0.08 |
| P for trendd | < 0.01 | < 0.01 | < 0.01 | ||||
a Multivariable Hazard ratios (95% CI) adjusted for body mass index and physical activity, both at enrollment
bHeterogeneity test for those with < 10 years of education compared with ≥13 years education
cNever smokers
dTrend test without never smokers