Table 4. Stratification of Lung Cancer and Pollutant Models by Potential Confounding Variables.
| Stratification variable | Case/control (n) | PM10 | NO2 | ||
|---|---|---|---|---|---|
| OR (95% CI) | p value* | OR (95% CI) | p value* | ||
| Smoking status† | 0.994 | 0.063 | |||
| Never smoker | 396/396 | 1.02 (0.85–1.23) | 1.17 (1.01–1.34) | ||
| Former | 306/306 | 1.01 (0.81–1.16) | 1.01 (0.85–1.19) | ||
| Current | 206/206 | 1.14 (0.85–1.52) | 0.92 (0.73–1.15) | ||
| Education‡ | 0.093 | 0.027 | |||
| More than high school | 186/228 | 1.35 (1.00–1.83) | 1.35 (1.06–1.68) | ||
| High school | 320/331 | 0.91 (0.72–1.14) | 0.97 (0.82–1.14) | ||
| Less than high school | 355/326 | 1.07 (0.88–1.30) | 1.15 (0.98–1.34) | ||
| Sex§ | 0.881 | 0.377 | |||
| Male | 566/566 | 1.07 (0.91–1.27) | 1.05 (0.92–1.18) | ||
| Female | 342/342 | 1.05 (0.85–1.29) | 1.15 (0.98–1.35) | ||
| Family history of cancer|| | 0.874 | 0.953 | |||
| None | 565/709 | 1.07 (0.92–1.25) | 1.10 (0.98–1.23) | ||
| Other cancers | 282/174 | 1.03 (0.79–1.36) | 1.07 (0.87–1.32) | ||
| Lung cancer | 61/25 | 1.03 (0.53–2.02) | 0.97 (0.64–1.46) | ||
| Occupational carcinogens¶ | 0.655 | 0.692 | |||
| No | 569/579 | 1.12 (0.95–1.32) | 1.13 (0.99–1.28) | ||
| Yes | 293/202 | 1.04 (0.82–1.33) | 1.08 (0.89–1.31) | ||
| Fruit consumption** | 0.196 | 0.600 | |||
| 1–3 times/month | 187/114 | 1.44 (1.06–1.96) | 1.03 (0.80–1.32) | ||
| 1–6 times/week | 396/472 | 1.05 (0.88–1.26) | 1.11 (0.96–1.28) | ||
| At least once/day | 279/195 | 1.01 (0.77–1.31) | 1.20 (0.98–1.46) | ||
OR, odds ratio; CI, confidence interval; SHS, secondhand smoke.
*Interaction p values were based on a log likelihood ratio test. All models are single pollutant, †Adjusted for age, sex, education, occupational carcinogens, and frequency of fruit intake, ‡Adjusted for age, sex, smoking, exposure to SHS at home and work, occupational carcinogens, family history of cancer, and frequency of fruit intake, §Adjusted for age, smoking, exposure to SHS at home and work, occupational carcinogens, family history of cancer, and frequency of fruit intake, ∥Adjusted for age, sex, smoking, exposure to SHS at home and work, occupational carcinogens, and frequency of fruit intake, ¶Adjusted for age, smoking, sex, exposure to SHS at home and work, family history of cancer, and frequency of fruit intake, **Adjusted for age, sex, smoking, education, occupational carcinogens, and family history of cancer.