Table 1.
Demographic and clinical characteristics
| Characteristic | SEER | SEER-medicare | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Training cohort | Test cohort | Validation cohort | All | Stand. diff.† | P value* | CCI = 0 | CCI = 1 | CCI > 1 | All | Stand. diff.† | P value* | |
| Patients, n | 44,069 | 14,690 | 8638 | 67,397 | 10,611 | 1495 | 471 | 12,577 | ||||
| Mean age at diagnosis, y (SD) | 63 (12) | 63 (12) | 69 (9) | 63 (12) | 0.33 | <.001 | 75 (6) | 75 (6) | 75 (6) | 75 (6) | 0.04 | .18 |
| Race, n (%) | 0.09 | <.001 | 0.18 | <.001 | ||||||||
| White | 38,775 (88) | 12,960 (88.2) | 7305 (84.6) | 59,040 (87.6) | 9613 (90.6) | 1284 (85.9) | 379 (80.5) | 11,276 (89.7) | ||||
| Black | 2009 (4.6) | 670 (4.6) | 651 (7.5) | 3330 (4.9) | 511 (4.8) | 117 (7.8) | 65 (13.8) | 693 (5.5) | ||||
| Other | 3285 (7.4) | 1060 (7.2) | 682 (7.9) | 5027 (7.5) | 487 (4.6) | 94 (6.3) | 27 (5.7) | 608 (4.8) | ||||
| Married, n (%) | 24,298 (55.1) | 8125 (55.3) | 4254 (49.2) | 36,677 (54.4) | 0.08 | <.001 | 4960 (46.7) | 573 (38.3) | 159 (33.8) | 5692 (45.3) | 0.14 | <.001 |
| Higher SES, n (%)‡ | 21,160 (48) | 7192 (49) | 3036 (35.1) | 31,388 (46.6) | 0.18 | <.001 | 3536 (33.3) | 382 (25.5) | 137 (29.1) | 4055 (32.2) | 0.11 | <.001 |
| Stage, n (%) | 0.24 | <.001 | 0.08 | .002 | ||||||||
| IA | 33,926 (77) | 11,211 (76.3) | 5634 (65.2) | 50,771 (75.3) | 6911 (65.1) | 901 (60.3) | 275 (58.4) | 8087 (64.3) | ||||
| IB | 6004 (13.6) | 2071 (14.1) | 1965 (22.7) | 10,040 (14.9) | 2442 (23) | 386 (25.8) | 128 (27.2) | 2956 (23.5) | ||||
| IIA/II NOS | 2963 (6.7) | 990 (6.7) | 445 (5.2) | 4398 (6.5) | 763 (7.2) | 123 (8.2) | 41 (8.7) | 927 (7.4) | ||||
| II | 1176 (2.7) | 418 (2.9) | 594 (6.9) | 2188 (3.3) | 495 (4.7) | 85 (5.7) | 27 (5.7) | 607 (4.8) | ||||
| Grade, n (%) | 0.07 | <.001 | 0.09 | <.001 | ||||||||
| 1 | 22,015 (50) | 7339 (50) | 3954 (45.8) | 33,308 (49.4) | 4729 (44.6) | 593 (39.7) | 174 (36.9) | 5496 (43.7) | ||||
| 2 | 15,719 (35.6) | 5164 (35.1) | 3173 (36.7) | 24,056 (35.7) | 3958 (37.3) | 605 (40.4) | 191 (40.6) | 4754 (37.8) | ||||
| 3 | 6335 (14.4) | 2187 (14.9) | 1511 (17.5) | 10,033 (14.9) | 1924 (18.1) | 297 (19.9) | 106 (22.5) | 2327 (18.5) | ||||
| Lymphadenectomy, n (%) | 1.61 | <.001 | 0.04 | .24 | ||||||||
| 0 nodes | 23,161 (52.6) | 7610 (51.8) | 2707 (31.3) | 33,478 (49.7) | 4882 (46) | 725 (48.5) | 222 (47.2) | 5829 (46.4) | ||||
| 1–10 nodes | 9011 (20.4) | 3110 (21.2) | 2250 (26.1) | 14,371 (21.3) | 2519 (23.7) | 356 (23.8) | 117 (24.8) | 2992 (23.8) | ||||
| >10 nodes | 11,897 (27) | 3970 (27) | 3681 (42.6) | 19,548 (29.0) | 3210 (30.3) | 414 (27.7) | 132 (28) | 3756 (29.8) | ||||
Abbreviations: CCI = Charlson Comorbidity Index; NOS = not otherwise specified; SEER = Surveillance, Epidemiology, and End Results; SES = socioeconomic status.
*
P values for categorical and continuous variables were generated from χ2 tests and analysis of variance, respectively.
†
Standardized difference compares differences in means (or proportions) in units of the pooled standard deviation; imbalances are defined as absolute values greater than 0.20 (small effect size). Standardized difference is not influenced by sample size.
‡
Higher SES = above $47,070 annual salary.