Table 2 Baseline characteristics of hardcore smokers among current male smokers aged 55–74 years old with histories of more than 30 pack-years of smoking
Variable |  | All (N = 4,763,098) | Hardcore smoker (N = 1,576,339) | Non-hardcore smoker (N = 3,186,759) | P-value |
|---|---|---|---|---|---|
Age | mean ± SD | 62.88 ± 0.20 | 63.91 ± 0.35 | 62.37 ± 0.25 | 0.0006 |
55 ≤ age < 60 | 1,487,173 (31.23) | 375,438 (23.82) | 1,111,735 (34.89) | 0.0052 | |
60 ≤ age < 65 | 1,557,224 (32.69) | 507,820 (32.22) | 1,049,403 (32.93) | ||
65 ≤ age < 70 | 1,016,798 (21.35) | 377,478 (23.95) | 639,320 (20.06) | ||
70 ≤ age < 75 | 701,902 (14.74) | 315,602 (20.02) | 386,300 (12.12) | ||
BMI, kg/m2 | mean ± SD | 23.14 ± 0.11 | 22.82 ± 0.21 | 23.30 ± 0.13 | 0.0487 |
Household income | 1st quartile | 1,548,917 (33.24) | 600,812 (39.40) | 948,105 (30.25) | 0.1380 |
2nd quartile | 1,287,828 (27.64) | 391,740 (25.69) | 896,088 (28.59) | ||
3rd quartile | 1,034,921 (22.21) | 315,490 (20.69) | 719,431 (22.95) | ||
4th quartile | 787,801 (16.91) | 216,823 (14.22) | 570,978 (18.22) | ||
Education | Elementary school or lower | 1,984,579 (41.79) | 780,634 (49.61) | 1,203,944 (37.91) | 0.0149 |
Middle school | 1,083,487 (22.81) | 328,611 (20.88) | 754,877 (23.77) | ||
High school or higher | 1,681,244 (35.40) | 464,265 (29.51) | 1,216,979 (38.32) | ||
Occupation | White collar job | 238,122 (5.03) | 55,322 (3.55) | 182,799 (5.76) | 0.3717 |
Blue collar job | 2,972,211 (62.84) | 973,748 (62.53) | 1,998,463 (62.99) | ||
Unemployed | 1,519,481 (32.13) | 528,295 (33.92) | 991,186 (31.24) | ||
Marriage | Married/cohabiting | 4,253,914 (90.30) | 1,377,576 (88.43) | 2,876,338 (91.23) | 0.2296 |
Single, never-married | 456,756 (9.70) | 180,293 (11.57) | 276,463 (8.77) | ||
Underlying disease | Hypertension | 1,482,919 (31.13) | 534,463 (33.91) | 948,456 (29.76) | 0.2519 |
Diabetes mellitus | 929,758 (19.52) | 297,874 (18.90) | 631,884 (19.83) | 0.7799 | |
Cardiovascular disease | 296,749 (6.23) | 94,423 (5.99) | 202,326 (6.35) | 0.8715 | |
Dyslipidemia | 556,939 (11.69) | 165,662 (10.51) | 391,277 (12.28) | 0.5366 | |
Cerebral vascular accident | 172,143 (3.61) | 69,577 (4.41) | 102,566 (3.22) | 0.4451 | |
Depression | 64,651 (1.36) | 41,320 (2.62) | 23,332 (0.73) | 0.0240 | |
FEV1/FVC | < 0.7 | 1,572,220 (43.43) | 535,954 (46.77) | 1,036,267 (41.88) | 0.3029 |
≥ 0.7 | 2,048,217 (56.57) | 610,074 (53.23) | 1,438,143 (58.12) |