Table 1.
Distribution of selected characteristics in Chinese case–control study population.
| Characteristics | Cases n (%) | Controls n (%) | P value |
|---|---|---|---|
| Over all | 627 | 633 | |
| Age (years) | |||
| Mean (± SD) | 58 (± 10.4) | 58 (± 10.5) | 0.846a |
| ≤ 40 | 29 (4.6%) | 29 (4.6%) | |
| 41–50 | 109 (17.4%) | 125 (19.7%) | |
| 51–60 | 222 (35.4%) | 214 (33.8%) | 0.748b |
| > 60 | 267 (42.6%) | 265 (41.9%) | |
| Sex | |||
| Female | 185 (29.5%) | 184 (29.1%) | |
| Male | 442 (70.5%) | 449 (70.9%) | 0.86b |
| Family history of cancer | |||
| No | 536 (85.5%) | 628 (99.2%) | |
| Yes | 91 (14.5%) | 5 (0.8%) | < 0.0001b |
| Smoking duration | |||
| Never | 241 (38.4%) | 333 (52.6%) | |
| ≤ 20 (years) | 104 (16.6%) | 98 (15.5%) | < 0.0001b |
| > 20 (years) | 282 (45.0%) | 202 (31.9%) | |
| Histopathology | |||
| Lung squamous cell carcinoma | 266 (42.4%) | ||
| Lung adenocarcinoma | 251(40.0%) | ||
| Other | 110 (17.6%) | ||
aFor Mann–Whitney U test (P < 0.0001 for Shapiro–Wilk test).
bFor χ2 test (two-sided), boldface indicates statistical significance.