Table 1 Characteristics of the study population by education, the Norwegian Health Screening Surveys, 1974–2003, (N = 595,675)

Subjects (%)

64,024

(22)

76,455

(25)

155,905

(55)

169,949

(55)

66,332

(23)

63,010

(20)

286,261

(48)

309,414

(52)

Lung cancer cases^a, n (%)

1646

(44)

1338

(47)

1759

(46)

1297

(45)

385

(10)

238

(8)

3790

2873

Lung cancer deaths, n (%)

1517

(46)

1138

(48)

1473

(44)

1056

(44)

333

(10)

185

(8)

3323

2379

Person-years of follow up

1,365,688

1,666,446

3,106,850

3,429,805

1,314,443

1,224,279

5,786,981

6,320,530

Body mass index (mean, SD)

26 (3)

25 (4)

26 (3)

25 (4)

25 (3)

24 (4)

26 (3)

25 (4)

Heavy physical activity^b (%)

28

14

36

22

41

28

35

20

Never smokers (%)

20

33

32

38

50

57

33

41

Former smokers (%)

27

18

27

22

26

23

27

21

Current smokers (%)

53

49

41

40

24

20

40

38

Duration of smoking^c, years, median (interquartile range)

22

(15–26)

20

(15–25)

20

(13–25)

19

(10–23)

18

(10–22)

15

(8–20)

20

(13–25)

20

(10–23)

Cigarettes smoked per day^c, median (interquartile range)

15

(10–20)

10

(8–15)

15

(10–20)

10

(7–15)

12

(10–20)

10

(5–15)

15

(10–20)

10

(7–15)

Pack-years^c, median (interquartile range)

14

(8–21)

10

(5–16)

13

(7–20)

9

(4–15)

10

(5–18)

6

(3–12)

13

(7–20)

9

(4–15)

Age at enrollment, median (interquartile range)

42

(40–45)

42

(41–45)

41

(40–42)

41

(40–42)

42

(41–43)

41

(40–42)

41

(40–42)

41

(40–43)

Age at lung cancer death, never smokers, median (interquartile range)

75

(62–80)

77

(68–84)

62

(52–73)

64

(57–76)

57

(55–69)

61

(55–66)

63

(54–76)

66

(59–80)

Age at lung cancer death, current smokers, median (interquartile range)

66

(60–74)

63

(57–71)

63

(57–70)

60

(55–66)

64

(58–70)

61

(56–68)

64

(58–72)

62

(56–69)