Table 1 Characteristics of screening participants with abnormal results
Characteristics | Total (N = 7939 ) | Site A (n = 2657) | Site B (n = 3767) | Site C (n = 1515) | P-value |
|---|---|---|---|---|---|
Age | Â | Â | Â | Â | <0.001 |
 35–44 | 3421(43.09) | 1295(48.74) | 1526 (40.51) | 600 (39.60) |  |
 45–54 | 3440 (43.33) | 1080 (40.65) | 1711 (45.42) | 649 (42.84) |  |
 55–64 | 1078 (13.58) | 282 (10.61) | 530 (14.07) | 266 (17.56) |  |
Educational level | Â | Â | Â | Â | <0.001 |
 Primary school or below | 1914 (24.11) | 288 (10.84) | 740 (19.64) | 886 (58.48) |  |
 Junior high school | 2901 (36.54) | 1434 (53.97) | 1182 (31.38) | 285 (18.81) |  |
 High school | 2267 (28.56) | 259 (9.75) | 1782 (47.31) | 226 (14.92) |  |
 College and above | 500 (6.30) | 327 (12.31) | 63 (1.67) | 110 (7.26) |  |
 Missing | 357 (4.50) | 349 (13.14) | 0 (0.00) | 8 (0.53) |  |
Race | Â | Â | Â | Â | <0.001 |
 Han | 7477 (94.18) | 2316 (87.17) | 3735 (99.15) | 1426 (94.13) |  |
 Other | 116 (1.46) | 9 (0.34) | 26 (0.69) | 81 (5.35) |  |
 Missing | 346 (4.36) | 332 (12.50) | 6 (0.16) | 8 (0.53) |  |
Age of menarche | Â | Â | Â | Â | <0.001 |
 ≤ 13 | 2857 (35.99) | 660 (24.84) | 2012 (53.41) | 185 (12.21) |  |
 14–15 | 3388 (42.68) | 1268 (47.72) | 1199 (31.83) | 921 (60.79) |  |
 ≥ 16 | 1316 (16.58) | 729 (27.44) | 186 (4.94) | 401 (26.47) |  |
 Missing | 378 (4.76) | 0 (0.00) | 370 (9.82) | 8 (0.53) |  |
Menopause status | Â | Â | Â | Â | <0.001 |
 Postmenopausal | 1857 (23.39) | 511 (19.23) | 956 (25.38) | 390 (25.74) |  |
 Premenopausal | 6019 (75.82) | 2092 (78.74) | 2811 (74.62) | 1116 (73.66) |  |
 Missing | 63 (0.79) | 54 (2.03) | 0 (0.00) | 9 (0.59) |  |
Previous childbirth | Â | Â | Â | Â | 0.047 |
 Yes | 7854 (98.93) | 2621 (98.65) | 3738 (99.23) | 1495 (98.68) |  |
 No | 85 (1.07) | 36 (1.35) | 29 (0.77) | 20 (1.32) |  |
Age of first delivery | Â | Â | Â | Â | <0.001 |
 ≤ 35 | 7699 (96.98) | 2592 (97.55) | 3625 (96.23) | 1482 (97.82) |  |
 >35 | 52 (0.65) | 25 (0.94) | 18 (0.48) | 9 (0.59) |  |
 Missing | 188 (2.37) | 40 (1.51) | 124 (3.29) | 24 (1.58) |  |
Breastfeeding history | Â | Â | Â | Â | <0.001 |
 Yes | 7195 (90.63) | 2384 (89.73) | 3363 (89.28) | 1448 (95.58) |  |
 No | 683 (8.60) | 228 (8.58) | 404 (10.72) | 51 (3.37) |  |
 Missing | 61 (0.77) | 45 (1.69) | 0 (0.00) | 16 (1.06) |  |
Family history of breast cancer |  |  |  |  | < 0.001 |
 Yes | 65 (0.82) | 6 (0.23) | 11 (0.29) | 48 (3.17) |  |
 No | 7861 (99.02) | 2648 (99.66) | 3756 (99.71) | 1457 (96.17) |  |
 Missing | 13 (0.16) | 3 (0.11) | 0 (0.00) | 10 (0.66) |  |
Breast cancer screening history |  |  |  |  | < 0.001 |
 Yes | 1866 (23.50) | 988 (37.18) | 258 (6.85) | 620 (40.92) |  |
 No | 5813 (73.22) | 1634 (61.50) | 3509 (93.15) | 670 (44.22) |  |
 Missing | 260 (3.27) | 35 (1.32) | 0 (0.00) | 225 (14.85) |  |
US results# |  |  |  |  | — |
 BI-RADS 0 | 436 (5.49) | 9 (0.34) | 77 (2.04) | 350 (23.10) |  |
 BI-RADS 3 | 6049 (76.19) | 2528 (95.14) | 3521 (93.47) | — |  |
 BI-RADS 4 | 1437 (18.10) | 114 (4.29) | 163 (4.33) | 1160 (76.57) |  |
 BI-RADS 5 | 17 (0.21) | 6 (0.23) | 6 (0.16) | 5 (0.33) |  |