Table 3
Dose-response relationship
Smokers
Mild (1–10/day)
Moderate (11–20/day)
Heavy (>20/day)
Non-smokers
p<0.0001 (χ
2
for linear trend=18.365).
Cases
25
21
18
21
Controls
140
65
48
206
Odds ratio
1.75
3.17
3.68
–