Table 2

The crude and adjusted risk ratios with 95% confidence intervals of developing lung cancer among 16 209 middle aged men living in Oslo in 1972, according to level of education, type of occupation, and smoking habits

Incidence (1000/year)cRR95% CI*aRR95% CI
*Controlled for age at screening, nitrogen oxides, and the other conditions in the table.
aRR, adjusted risk ratio; CI, confidence interval; cRR, crude risk ratio; ref, reference category.
Education
<10 years1.871 (ref)1 (ref)
10–12 years1.030.540.44 to 0.660.670.54 to 0.82
12+ years0.670.350.25 to 0.470.520.38 to 0.71
Occupation
“White collar”0.901 (ref)1 (ref)
“Blue collar”
Moderate physical work1.331.501.19 to 1.871.271.00 to 1.62
Intermediate physical work1.701.921.50 to 2.471.250.94 to 1.65
Vigorous physical work1.541.751.10 to 2.791.110.68 to 1.80
Smoking habits
Non-smoker0.081 (ref)1 (ref)
1–9 cigarettes per day0.9811.904.98 to 28.3711.074.31 to 28.40
10–19 cigarettes per day1.8523.0310.20 to 51.8822.869.43 to 55.40
20+ cigarettes per day2.7935.2315.61 to 79.5036.4715.06 to 88.29
Smoker, amount not reported0.576.850.82 to 56.907.950.93 to 67.90
Former smoker0.354.241.77 to 10.144.581.79 to 11.71