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Table 4 Odds ratios between various smoking-related variables (continuous) and lung cancer risk

From: Risk of lung cancer in relation to various metrics of smoking history: a case-control study in Montreal

Model

Cigarette smoking variablesa

Unit

β estimate

ORb (95% CI)

DF

AIC

Δ AICc

Among men who ever smoked [N = 1 454]

1

Duration (Dur)

per year

(7.7 x 10-2) x Dur

1.08 [1.06 - 1.10]

24

1630

-

2

Intensity (Int)

per pack

0.84 x Log(Int)

2.31 [1.85 - 2.89]

24

1731

-22

3*

Pack-years (PY)

per pack-year

1.06 x Log(PY)

2.87 [2.35 - 3.52]

24

1646

-39

4

CSI index (CSI)

per unit

1.31 x CSI

3.70 [3.04 - 4.50]

24

1583

-

5

Duration (Dur)

per year

(7.2 x 10-2) x Dur

1.07 [1.06 - 1.09]

25

1602

-8

Intensity (Int)

per pack

0.64 x Log(Int)

1.90 [1.49 - 2.42]

6

Duration (Dur)

per year

variable not retained in the final model

25

1600

-10

Intensity (Int)

per pack

0.75 x Log(Int)

2.12 [1.66 - 2.70]

Time since cess. (TSC)

per year

(-7.9 x 10-2) x TSC

0.92 [0.91 - 0.94]

7

Pack-years (PY)

per pack-year

0.75 x Log(PY)

2.11 [1.70 - 2.61]

25

1588

-19

Time since cess. (TSC)

per year

-0.4 x Log(TSC)

0.67 [0.60 - 0.75]

Among women who ever smoked [N = 734]

1*

Duration (Dur)

per year

(8.1 x 10-2) x Dur

1.08 [1.06 - 1.11]

17

781

-

2*

Intensity (Int)

per pack

1.22 x Log(Int)

3.40 [2.47 - 4.66]

17

792

-33

3

Pack-years (PY)

per year

1.15 x Log(PY)

3.17 [2.41 - 4.16]

17

755

-21

4

CSI index (CSI)

per unit

1.74 x CSI

5.68 [4.02 - 8.00]

17

735

-

5*

Duration (Dur)

per year

(6.8 x 10-2) x Dur

1.07 [1.04 - 1.10]

18

743

-16

Intensity (Int)

per pack

1.05 x Log(Int)

2.87 [2.02 - 4.08]

6*

Duration (Dur)

per year

(3.8 x 10-2) x Dur

1.04 [1.00 - 1.08]

19

739

-16

Intensity (Int)

per pack

1.13 x Log(Int)

3.09 [2.15 - 4.45]

Time since cess. (TSC)

per year

(-5.0 x 10-2) x TSC

0.95 [0.91 - 0.99]

7*

Pack-years (PY)

per pack.year

0.97 x Log(PY)

2.63 [1.97 - 3.51]

18

741

-12

Time since cess. (TSC)

per year

-0.36 x Log(TSC)

0.70 [0.58 - 0.84]

  1. This table presents several model fits based on one or several smoking-related variables (continuous). Different functions were used to model the relations between continuous smoking metrics and the logit of the lung cancer risk, including linear and logarithmic functions models as well as fractional polynomials
  2. * More complex models are associated with better AIC values: the β estimates being respectively:
  3. - for Model 3 among men: 0.78 x PY0.5 - 0.03 x PY - AIC = 1638
  4. - for Model 1 among women: (3.4 x 10-4) x Dur3 + (-8 x 10-5) x Dur3 x log(Dur) - AIC = 773
  5. - for Model 2 among women: -2.09 x Int-0.5 - AIC = 785
  6. - for Model 5 among women: (6.6 x 10-2) x Dur and -1.79 x Int-0.5 - AIC = 740
  7. - for Model 6 among women: (4.1 x 10-2) x Dur, -1.9 x Int-0.5 and 0.89 x TSC-2 - AIC = 731
  8. - for Model 7 among women: 0.41 x PY0.5 and 1.03 x TSC-2 - AIC = 737
  9. aComputed after a discount up to 2 years when relevant
  10. bOdds ratio [OR] estimated with logistic regression, adjusted for age, respondent type, education, ethnic group, annual income and exposure to lung carcinogens [each exposure being considered separately – cf. the method section]
  11. cDifference in AIC criterion with linear model
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BMC Cancer

ISSN: 1471-2407

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