Appendix Table 1.
Characteristics of Case and Control Participants*
| Variable | CRC Incidence, n (%)† |
CRC Deaths, n (%)‡ |
||
|---|---|---|---|---|
| Case Participants | Control Participants | Case Participants | Control Participants | |
| Total ambulatory visits to PCP | ||||
| 0–1 | 29 089 (28.3) | 27 179 (26.4) | 8942 (33.0) | 7289 (26.9) |
| 2–4 | 19 451 (18.9) | 19 246 (18.7) | 5129 (18.9) | 5068 (18.7) |
| 5–10 | 29 681 (28.8) | 30 677 (29.8) | 7146 (26.4) | 8066 (29.8) |
| ≥11 | 24 681 (24.0) | 25 800 (25.1) | 5863 (21.7) | 6657 (24.6) |
| Total ambulatory visits to non-PCP | ||||
| 0–1 | 40 622 (39.5) | 39 993 (38.9) | 12 540 (46.3) | 10 615 (39.2) |
| 2–4 | 21 164 (20.6) | 21 300 (20.7) | 5333 (19.7) | 5646 (20.9) |
| 5–10 | 22 047 (21.4) | 22 485 (21.9) | 5158 (19.1) | 5870 (21.7) |
| ≥11 | 19 069 (18.5) | 19 124 (18.6) | 4049 (15.0) | 4949 (18.3) |
| Age | ||||
| ≤70 y | 17 618 (17.1) | 17 710 (17.2) | 4113 (15.2) | 4142 (15.3) |
| 71–75 y | 28 604 (27.8) | 28 517 (27.7) | 7146 (26.4) | 7146 (26.4) |
| 76–80 y | 31 088 (30.2) | 31 092 (30.2) | 8248 (30.5) | 8196 (30.3) |
| ≥81 y | 25 592 (24.9) | 25 583 (24.9) | 7573 (28.0) | 7596 (28.1) |
| Sex | ||||
| Male | 50 153 (48.7) | 40 768 (39.6) | 13 018 (48.1) | 10 681 (39.4) |
| Female | 52 749 (51.3) | 62 134 (60.4) | 14 062 (51.9) | 16 399 (60.6) |
| Race/ethnicity | ||||
| White, non-Hispanic | 88 306 (85.8) | 87 898 (85.4) | 22 950 (84.8) | 23 188 (85.6) |
| Black, non-Hispanic | 8264 (8.0) | 7073 (6.9) | 2567 (9.5) | 1909 (7.1) |
| Hispanic | 1341 (1.3) | 2113 (2.1) | 343 (1.3) | 598 (2.2) |
| Asian or Pacific Islander | 2851 (2.8) | 3545 (3.5) | 653 (2.4) | 832 (3.1) |
| Native American | 229 (0.2) | 318 (0.3) | 63 (0.2) | 83 (0.3) |
| Other | 1757 (1.7) | 1766 (1.7) | 450 (1.7) | 416 (1.5) |
| Unknown | 154 (0.2) | 189 (0.2) | 54 (0.2) | 54 (0.2) |
| Quintile of education level (derived at ZIP code level) | ||||
| 1 (lowest) | 20 654 (20.2) | 19 068 (19.1) | 5999 (22.4) | 5216 (19.9) |
| 2 | 20 821 (20.4) | 19 552 (19.5) | 5531 (20.6) | 5227 (19.9) |
| 3 | 20 708 (20.3) | 19 374 (19.5) | 5564 (20.8) | 5284 (20.1) |
| 4 | 20 481 (20.1) | 20 204 (20.3) | 5100 (19.0) | 5268 (20.1) |
| 5 (highest) | 19 363 (19.0) | 21 395 (21.5) | 4604 (17.2) | 5258 (20.0) |
| Quintile of median household income (derived at ZIP code level) | ||||
| 1 (lowest) | 20 474 (20.1) | 20 269 (20.4) | 5689 (21.2) | 5358 (20.4) |
| 2 | 20 703 (20.3) | 19 632 (19.7) | 5560 (20.7) | 5179 (19.7) |
| 3 | 20 701 (20.3) | 19 436 (19.5) | 5414 (20.2) | 5252 (20.0) |
| 4 | 20 479 (20.1) | 19 882 (20.0) | 5278 (19.7) | 5329 (20.3) |
| 5 (highest) | 19 670 (19.3) | 20 374 (20.5) | 4857 (18.1) | 5135 (19.6) |
| Type of metropolitan statistical area | ||||
| Large metropolitan | 57 252 (55.6) | 55 915 (54.5) | 15 201 (56.1) | 14 688 (54.4) |
| Metropolitan | 27 658 (26.9) | 28 457 (27.7) | 7140 (26.4) | 7429 (27.5) |
| Urban | 6765 (6.6) | 6737 (6.6) | 1787 (6.6) | 1819 (6.7) |
| Less urban | 9136 (8.9) | 9311 (9.1) | 2399 (8.9) | 2466 (9.1) |
| Rural | 2087 (2.0) | 2224 (2.2) | 550 (2.0) | 607 (2.2) |
| Charlson comorbidity index | ||||
| 0 | 58 682 (57.0) | 61 480 (59.8) | 16 057 (59.3) | 16 204 (59.8) |
| 1 | 24 059 (23.4) | 23 257 (22.6) | 5938 (21.9) | 6095 (22.5) |
| ≥2 | 20 161 (19.6) | 18 165 (17.7) | 5085 (18.8) | 4781 (17.7) |
| Influenza vaccination | ||||
| No | 50 932 (49.5) | 48 994 (47.6) | 14 859 (54.9) | 13 071 (48.3) |
| Yes | 51 970 (50.5) | 53 908 (52.4) | 12 221 (45.1) | 14 009 (51.7) |
| Previous CRC screening | ||||
| No | 55 747 (54.2) | 48 767 (47.4) | 16 145 (59.6) | 13 044 (48.2) |
| Yes | 47 155 (45.8) | 54 135 (52.6) | 10 935 (40.4) | 14 036 (51.8) |
| Screening method§ | ||||
| Fecal occult blood test | 38 903 (82.5) | 44 809 (82.8) | 9002 (82.3) | 11 617 (82.8) |
| Flexible sigmoidoscopy | 2255 (4.8) | 2755 (5.1) | 478 (4.4) | 677 (4.8) |
| Barium enema | 9716 (20.6) | 10 970 (20.3) | 2475 (22.6) | 3094 (22.0) |
| Colonoscopy | 10 362 (22.0) | 14 938 (27.6) | 2024 (18.5) | 3582 (25.5) |
| Previous polypectomy | ||||
| No | 88 571 (86.1) | 84 268 (81.9) | 24 431 (90.2) | 22 710 (83.9) |
| Yes | 14 331 (13.9) | 18 634 (18.1) | 2649 (9.8) | 4370 (16.1) |
| Stage at diagnosis | ||||
| 0 (in situ) | 7449 (7.2) | NA | 229 (0.9) | NA |
| I | 20 696 (20.1) | NA | 1283 (4.7) | NA |
| II | 26 305 (25.6) | NA | 3980 (14.7) | NA |
| III | 21 337 (20.7) | NA | 6745 (24.9) | NA |
| IV | 15 066 (14.6) | NA | 10 748 (39.7) | NA |
CRC = colorectal cancer; NA = not applicable; PCP = primary care physician.
All case and control comparisons are significant at P < 0.001 except non-PCP visits (P = 0.021 for incidence comparisons), age (P = 0.80 for incidence comparisons and 0.89 for mortality comparisons), comorbid conditions (P = 0.002 for mortality comparisons), fecal occult blood test (P = 0.25 for incidence comparisons and 0.36 for mortality comparisons), barium enema (P = 0.180 for incidence comparisons and 0.27 for mortality comparisons), and flexible sigmoidoscopy (P = 0.025 for incidence comparisons and 0.092 for mortality comparisons).
The total number of CRC case participants and matching control participants was 205 804.
The total number of CRC deaths and matching control participants was 54 160.
Of those with previous CRC screening. Numbers do not add to total because some participants had more than 1 screening method.