Table 1.
Baseline demographic and lifestyle characteristics and urinary biomarkers of cigarette smoke exposure in lung cancer cases and matched control subjects, The Shanghai Cohort Study 1986–2013
| Characteristics or biomarkers | Cases | Controls | P* |
|---|---|---|---|
| Number of subjects | 610 | 610 | |
| Mean age (SD), years | 57.3 (5.2) | 57.1 (5.0) | 0.513a |
| Men, N (%) | 610 (100) | 610 (100) | 1.000a |
| Mean body mass index (SD), kg/m2 | 21.6 (2.8) | 22.1 (3.1) | 0.001 |
| Level of education, N (%) | |||
| No formal education | 51 (8.4) | 41 (6.7) | 0.225 |
| Primary school (1–6 years) | 204 (33.4) | 186 (30.5) | |
| Secondary school or higher | 355 (58.2) | 383 (62.8) | |
| Smoking status, N (%) | |||
| Non-smokers | 116 (19.0) | 116 (19.0) | 1.000a |
| Former smokers | 58 (9.5) | 58 (9.5) | |
| Current smokers | 436 (71.5) | 436 (71.5) | |
| Mean cigarettes/day (SD)b | 20.2 (8.6) | 15.4 (7.6) | <0.001 |
| Mean years of smoking (SD)b | 34.7 (8.5) | 30.6 (10.5) | <0.001 |
| Mean pack-years of smoking (SD)b | 35.5 (18.0) | 24.3 (15.3) | <0.001 |
| Alcohol drinking status, N (%) | |||
| Non-drinkers | 292 (47.9) | 278 (45.6) | 0.421 |
| Regular drinkers | 318 (52.1) | 332 (54.4) | |
| Mean drinks/day (SD)c | 3.0 (2.7) | 2.5 (2.2) | 0.005 |
| Urinary biomarkers of cigarette smoking | |||
| Total cotinine (nmol/mg Cr)d | 13.38 (12.16, 14.76) | 6.98 (6.32, 7.68) | <0.001 |
| Total NNAL (pmol/mg Cr)d | 0.28 (0.26, 0.30) | 0.20 (0.18, 0.20) | <0.001 |
| PheT (pmol/mg Cr)d | 32.38 (30.66, 34.18) | 28.10 (26.62, 29.68) | <0.001 |
Cr, creatinine; SD, standard deviation.aAge, sex and smoking status were matched between cases and controls.
bAmong ever smokers.
cAmong regular alcohol drinkers only.
dAmong current smokers only; geometric means (95% confidence intervals) are shown.
*Two-sided P’s were based on t test for continuous variables or chi-square test for categorical or nominal variables.