Table 1.
Distribution of study population by age and smoking status
| Control (N = 1069) | Cases (N = 1208) | p value* | ||
|---|---|---|---|---|
| Age (year-old) | Mean ± SD# | 66.2 ± 0.3 | 65.8 ± 0.3 | 0.326 |
| < 50 | 92 ( 8.6) | 98 ( 8.1) | 0.060 | |
| 50–60 | 167 (15.6) | 206 (17.1) | ||
| 60–70 | 326 (30.5) | 419 (34.7) | ||
| ≥ 70 | 484 (45.3) | 485 (40.1) | ||
| Education | Primary school or below | 142 (13.5) | 298 (25.1) | < 0.001 |
| Middle school | 383 (36.4) | 525 (44.2) | ||
| College or above | 528 (50.1) | 366 (30.8) | ||
| Marital status | Married | 183 (17.3) | 198 (16.6) | 0.646 |
| Others | 876 (82.7) | 998 (83.4) | ||
| Monthly income (HKD) | < 4000 | 456 (42.7) | 735 (60.8) | < 0.001 |
| > 4000 | 285 (26.7) | 306 (25.3) | ||
| No answer | 328 (30.7) | 167 (13.8) | ||
| History of lung diseases | Yes | 112 (10.5) | 286 (23.7) | < 0.001 |
| Cancer history in first-degree relatives | Yes | 134 (12.5) | 239 (19.8) | < 0.001 |
| Smoking | ||||
|
Smoking status n (%) |
Never | 536 (50.1) | 132 (10.9) | < 0.001 |
| Former | 357 (33.4) | 340 (28.1) | ||
| Current | 176 (16.5) | 736 (60.9) | ||
| Pack-years | Non-smokers | 547 (51.2) | 140 (11.6) | < 0.001 |
| < 20 | 172 (16.1) | 122 (10.1) | ||
| 20–40 | 171 (16.0) | 317 (26.2) | ||
| ≥ 40 | 179 (16.7) | 629 (52.1) | ||
| Smoking cessation | Smoker | 176 (16.7) | 736 (61.4) | < 0.001 |
| 2–5 years | 45 ( 4.3) | 81 ( 6.8) | ||
| 5–10 years | 55 ( 5.2) | 65 ( 5.4) | ||
| 10–20 years | 100 ( 9.5) | 98 ( 8.2) | ||
| ≥ 20 years | 145 (13.7) | 87 ( 7.3) | ||
| non-smokers | 536 (50.7) | 132 (11.0) | ||
| ETS exposure | No | 281 (26.3) | 230 (19.1) | < 0.001 |
| Yes | 788 (73.7) | 977 (80.9) | ||
| Exposure of indoor air pollutants | ||||
| Radon | Mean ± SD | 8.79 ± 1.30 | 8.93 ± 1.22 | 0.008 |
| Median (range) | 8.86 (5.46–13.00) | 8.86 (5.17–14.00) | ||
| < 25 (5.17–8.11) | 263 (24.6) | 230 (19.0) | 0.005 | |
| 25–50 (8.11–8.64) | 261 (24.4) | 301 (24.9) | ||
| 50–75 (8.64–9.77) | 277 (25.9) | 318 (26.3) | ||
| > 75 (9.77–13.00) | 268 (25.1) | 359 (29.7) | ||
| Incense burning at home | Yes | 590 (55.2) | 776 (64.2) | < 0.001 |
| Mosquito coil burning | Yes | 160 (15.1) | 220 (18.3) | 0.036 |
| PM10 exposure | ||||
| Annual average exposure | Mean ± SD | 73.1 ± 0.4 | 75.7 ± 0.3 | < 0.001 |
| Median (range) |
73.22 (35.89–117.27) |
75.45 (44.43–110.30) |
||
| Occupational exposure | ||||
| Carcinogen exposure | Yes | 453 (42.4) | 624 (51.7) | < 0.001 |
| Mask used in workplace | Yes | 112 (10.5) | 116 ( 9.6) | 0.488 |
| Ventilation in workplace | Yes | 976 (91.3) | 1065 (88.2) | 0.014 |
| Dust control in workplace | Yes | 1022 (95.6) | 1009 (83.5) | < 0.001 |
| Dietary habits and drinking habits | ||||
| Fruit/green tea | ≥ 1 time /day | 422 (39.5) | 442 (36.6) | 0.157 |
| Meat | ≥ 1 time /day | 253 (23.7) | 128 (10.6) | < 0.001 |
| Preserved food | ≥ 1 time /day | 198 (18.5) | 325 (26.9) | < 0.001 |
| Alcohol drinking | Non-drinkers | 551 (51.5) | 451 (37.4) | < 0.001 |
| < 4 times /week | 314 (29.4) | 331 (27.4) | ||
| ≥ 4 times /week | 204 (19.1) | 425 (35.2) | ||
* p value from the two-sided chi-square test for categorical variables and Student’s t test for continuous variables
# SD, Standard deviation