Table 2. Baseline characteristics of National Lung Screening Trial and Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial participants according to 6-y lung cancer incidence.
| Characteristic | NLST computed tomography arm | NLST chest radiography arm | PLCO chest radiography arm | PLCO control arm | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No lung cancer | Lung cancer | p-Value | No lung cancer | Lung cancer | p-Value | No lung cancer | Lung cancer | p-Value | No lung cancer | Lung cancer | p-Value | |
| Number (percent) of participants | 25,692 (96.15%) | 1,030 (3.85%) | 25,835 (96.65%) | 895 (3.35%) | 39,846 (98.14%) | 754 (1.86%) | 39,363 (98.23%) | 709 (1.77%) | ||||
| Age (years) | ||||||||||||
| Median (IQR) | 60 (57–65) | 63 (59–68) | <0.001 | 60 (57–65) | 64 (60–68) | <0.001 | 62 (58–66) | 65 (60.25–69) | <0.001 | 62 (58–66) | 65 (60–69) | <0.001 |
| Missing | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | ||||
| Gender | ||||||||||||
| Male | 15,148 (58.96%) | 621 (60.29%) | 0.401 | 15,235 (58.97%) | 526 (58.77%) | 0.917 | 23,228 (58.29%) | 475 (63.00%) | 0.010 | 22,775 (57.86%) | 438 (61.78%) | 0.038 |
| Female | 10,544 (41.04%) | 409 (39.71%) | 10,600 (41.03%) | 369 (41.23%) | 16,618 (41.71%) | 279 (37.00%) | 16,588 (42.14%) | 271 (38.22%) | ||||
| Missing | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | ||||
| Hispanic ethnicity | ||||||||||||
| No | 25,070 (97.58%) | 1,008 (97.86%) | 0.041 | 25,158 (97.38%) | 881 (98.44%) | 0.004 | 38,116 (95.66%) | 731 (96.95%) | 0.314 | 37,597 (95.51%) | 690 (97.32%) | 0.093 |
| Yes | 469 (1.83%) | 10 (0.97%) | 451 (1.75%) | 5 (0.56%) | 872 (2.19%) | 12 (1.59%) | 873 (2.22%) | 9 (1.27%) | ||||
| Missing | 153 (0.60%) | 12 (1.17%) | 226 (0.87%) | 9 (1.01%) | 858 (2.15%) | 11 (1.46%) | 893 (2.27%) | 10 (1.41%) | ||||
| Race or ethnic group | ||||||||||||
| White | 23,019 (89.60%) | 933 (90.58%) | 0.323 | 23,143 (89.58%) | 806 (90.06%) | 0.090 | 35,180 (88.29%) | 644 (85.41%) | <0.001 | 34,787 (88.37%) | 630 (88.86%) | 0.007 |
| Black | 1,140 (4.44%) | 47 (4.56%) | 1,123 (4.35%) | 51 (5.70%) | 2,252 (5.65%) | 73 (9.68%) | 2,201 (5.59%) | 53 (7.48%) | ||||
| Hispanic | 337 (1.31%) | 7 (0.68%) | 314 (1.22%) | 4 (0.45%) | 810 (2.03%) | 12 (1.59%) | 807 (2.05%) | 8 (1.13%) | ||||
| Asian | 541 (2.11%) | 18 (1.75%) | 522 (2.02%) | 14 (1.56%) | 1232 (3.09%) | 16 (2.12%) | 1199 (3.05%) | 13 (1.83%) | ||||
| Native Hawaiian or Pacific Islander | 88 (0.34%) | 3 (0.29%) | 100 (0.39%) | 2 (0.22%) | 219 (0.55%) | 8 (1.06%) | 244 (0.62%) | 1 (0.14%) | ||||
| American Indian or Alaskan Native | 86 (0.33%) | 6 (0.58%) | 95 (0.37%) | 3 (0.34%) | 130 (0.33%) | 1 (0.13%) | 105 (0.27%) | 4 (0.56%) | ||||
| Missing | 481 (1.87%) | 16 (1.55%) | 538 (2.08%) | 15 (1.68%) | 23 (0.06%) | 0 (0%) | 20 (0.05%) | 0 (0%) | ||||
| Education | ||||||||||||
| Less than high school graduate | 1,552 (6.04%) | 89 (8.64%) | <0.001 | 1,525 (5.90%) | 83 (9.27%) | <0.001 | 3,424 (8.59%) | 123 (16.31%) | <0.001 | 3,418 (8.68%) | 96 (13.54%) | <0.001 |
| High school graduate | 5,989 (23.31%) | 284 (27.57%) | 6,177 (23.91%) | 261 (29.16%) | 8,775 (22.20%) | 199 (26.39%) | 8,647 (21.97%) | 197 (27.79%) | ||||
| Post-high-school training | 3,587 (13.96%) | 146 (14.17%) | 3,562 (13.79%) | 139 (15.53%) | 5,341 (13.40%) | 92 (12.20% | 5,393 (13.70%) | 98 (13.82%) | ||||
| Some college | 5,957 (23.19%) | 232 (22.52%) | 5,893 (22.81%) | 195 (21.79%) | 9,269 (23.26%) | 165 (21.88%) | 9,159 (23.27%) | 161 (22.71%) | ||||
| College graduate | 4,357 (16.96%) | 148 (14.37%) | 4,342 (16.81%) | 99 (11.06%) | 6,626 (16.63%) | 97 (12.86%) | 6,385 (16.22%) | 94 (13.26%) | ||||
| Postgraduate/professional | 3,679 (14.32%) | 101 (9.81%) | 3,718 (14.39%) | 102 (11.40%) | 6,352 (15.94%) | 77 (10.21%) | 6,218 (15.80% | 59 (8.32%0 | ||||
| Missing | 571 (2.22%) | 30 (2.91%) | 618 (2.39%) | 16 (1.79%) | 59 (0.15%) | 1 (0.13%) | 143 (0.36%) | 4 (0.56%) | ||||
| BMI (kg/m2) | ||||||||||||
| Median (IQR) | 27.32 (24.46–30.73) | 26.38 (23.94–29.28) | <0.001 | 27.38 (24.50–30.63) | 26.22 (23.62–29.25) | <0.001 | 26.68 (24.19–30.02) | 26.16 (23.48–28.77) | <0.001 | 26.68 (24.18–29.90) | 25.88 (23.45–28.81) | <0.001 |
| Missing | 146 (0.57%) | 13 (1.26%) | 206 (0.80%) | 7 (0.78%) | 494 (1.24%) | 10 (1.33%) | 742 (1.89%) | 15 (2.12%) | ||||
| COPD | ||||||||||||
| No | 21,283 (82.84%) | 765 (74.27%) | <0.001 | 21,435 (82.97%) | 643 (71.84%) | <0.001 | 36,381 (91.30%) | 602 (79.84%) | <0.001 | 35,899 (91.20%) | 567 (79.97%) | <0.001 |
| Yes | 4,409 (17.16%) | 265 (25.73%) | 4,400 (17.03%) | 252 (28.16%) | 3,465 (8.70%) | 152 (20.16%) | 3,464 (8.80%) | 142 (20.03%) | ||||
| Missing | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | ||||
| Emphysema | ||||||||||||
| No | 23,661 (92.09%) | 878 (85.24%) | <0.001 | 23,734 (91.87%) | 766 (85.59%) | <0.001 | 38,011 (95.39%) | 655 (86.87%) | <0.001 | 37,404 (95.02%) | 599 (84.49%) | <0.001 |
| Yes | 1,910 (7.43%) | 146 (14.17%) | 1,915 (7.41%) | 122 (13.63%) | 1,650 (4.14%) | 96 (12.73%) | 1,612 (4.10%) | 99 (13.96%) | ||||
| Missing | 121 (0.47%) | 6 (0.58%) | 186 (0.72%) | 7 (0.78%) | 185 (0.46%) | 3 (0.40%) | 347 (0.88%) | 11 (1.55%) | ||||
| Personal history of cancer | ||||||||||||
| No | 24,588 (95.70%) | 956 (92.82%) | <0.001 | 24,554 (95.04%) | 833 (93.07%) | 0.007 | 38,033 (95.45%) | 709 (94.03%) | 0.078 | 37,532 (95.35%) | 653 (92.10%) | <0.001 |
| Yes | 1,028 (4.00%) | 68 (6.60%) | 1,154 (4.47%) | 58 (6.48%) | 1,813 (4.55%) | 45 (5.97%) | 1,831 (4.65%) | 56 (7.90%) | ||||
| Missing | 76 (0.30%) | 6 (0.58%) | 127 (0.49%) | 4 (0.45%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | ||||
| Family history of lung cancer | ||||||||||||
| No | 19,741 (76.84%) | 746 (72.43%) | 0.004 | 19,812 (76.69%) | 640 (71.51%) | 0.001 | 33,718 (84.62%) | 565 (74.93%) | <0.001 | 33,485 (85.07%) | 541 (76.30%) | <0.001 |
| Yes | 5,554 (21.62%) | 261 (25.34%) | 5,570 (21.56%) | 236 (26.37%) | 4,514 (11.33%) | 139 (18.44%) | 4,414 (11.21%) | 130 (18.34%) | ||||
| Missing | 397 (1.55%) | 23 (2.23%) | 453 (1.75%) | 19 (2.22%) | 1614 (4.05%) | 50 (6.63%) | 1464 (3.72%) | 38 (5.36%) | ||||
| Personal history of pneumonia | ||||||||||||
| No | 19,905 (77.48%) | 781 (75.83%) | 0.338 | 20,023 (77.50%) | 657 (73.41%) | 0.004 | Not measured in PLCO | — | Not measured in PLCO | — | ||
| Yes | 5,690 (22.15%) | 240 (23.30%) | 5,646 (21.85%) | 233 (26.03%) | Not measured in PLCO | — | Not measured in PLCO | — | ||||
| Missing | 97 (0.38%) | 9 (0.87%) | 166 (0.64%) | 5 (0.56%) | Not measured in PLCO | — | Not measured in PLCO | — | ||||
| Smoking status | ||||||||||||
| Current smoker | 12,183 (47.42%) | 601 (58.35%) | <0.001 | 12,274 (47.51%) | 558 (62.35%) | <0.001 | 7,744 (19.43%) | 332 (44.04%) | <0.001 | 7,655 (19.45%) | 324 (45.70%) | <0.001 |
| Former smoker | 13,509 (52.58%) | 429 (41.65%) | 13,561 (52.49%) | 337 (37.65%) | 32,102 (80.57%) | 422 (55.97%) | 31,708 (80.55%) | 385 (54.30%) | ||||
| Missing | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | ||||
| Smoking duration (years) | ||||||||||||
| Median (IQR) | 40 (35–44) | 44 (40–49) | <0.001 | 40 (35–44) | 44 (40–49) | <0.001 | 28 (16–39) | 42 (35–48) | <0.001 | 28 (16–39) | 42 (35–47) | <0.001 |
| Missing | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 766 (1.92%) | 10 (1.33%) | 877 (2.23%) | 17 (2.40%) | ||||
| Smoking intensity (cigarettes per day) | ||||||||||||
| Median (IQR) | 25 (20–35) | 30 (20–40) | <0.001 | 25 (20–30.5) | 25 (20–40) | 0.029 | 20 (10–30) | 30 (20–40) | <0.001 | 20 (10–30) | 30 (20–40) | <0.001 |
| Missing | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 78 (0.20%) | 4 (0.53%) | 112 (0.28%) | 2 (0.28%) | ||||
| Pack-years of smoking | ||||||||||||
| Median (IQR) | 48 (39–66) | 57 (45–82) | <0.001 | 48 (39–66) | 55.5 (44–78) | <0.001 | 28.5 (14–48) | 51 (38–74) | <0.001 | 29 (14–49) | 54 (40–75) | <0.001 |
| Missing | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 827 (2.1%) | 13 (1.7%) | 957 (2.4% | 19 (2.7%) | ||||
| Years since cessation | ||||||||||||
| Median (IQR) | 7 (3–11) | 5 (2–10) | <0.001 | 7 (3–11) | 6 (2–11) | 0.067 | 20 (10–30) | 10 (4–19) | <0.001 | 20 (10–30) | 10 (4–18.25) | <0.001 |
| Missing | 219 (0.9%) | 5 (0.5%) | 216 (0.8%) | 8 (0.9%) | 561 (1.4%) | 5 (0.7%) | 679 (1.7%) | 5 (0.7%) | ||||
Data are given as n (percent) or median (IQR).
BMI, body mass index; COPD, chronic obstructive pulmonary disease; IQR, interquartile range; NLST, National Lung Screening Trial; PLCO, Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.