Table 1. Characteristics of participants in the study.
| Overall | MCCS | ABCFR | ||
|---|---|---|---|---|
| Number of women (number of mammograms) | 1064 (4714) | 846 (3951) | 218 (763) | |
| Number of mammograms per woman, median (range) | 4 (1-14) | 5 (1-10) | 3 (1-14) | |
| Number of women with one mammogram, N (%) | 141 (13) | 80 (9) | 61 (28) | |
| Mean (SD) | ||||
|
|
||||
| Time interval between mammograms, years | 2.2 (1.0) | 2.2 (0.8) | 2.2 (1.7) | |
| Age at first mammogram, years | 55.8 (9.8) | 58.9 (7.6) | 44.0 (8.3) | |
| Age at last mammogram, years | 63.4 (10.7) | 67.0 (7.8) | 49.4 (8.7) | |
| BMI at study entry, kg/m2 | 26.8 (5.1) | 27.5 (5.1) | 24.1 (4.3) | |
| BMI at first mammogram, kg/m2 | 27.0 (5.6) | 27.5 (5.1) | 24.8 (6.9) | |
| BMI at last mammogram, kg/m2 | 26.8 (5.1) | 27.5 (5.1) | 24.1 (4.3) | |
| Median (25th-75th percentile) | ||||
|
|
||||
| Time between first and last mammograms, years | 8.0 (5.0) | 8.4 (4.9) | 4.5 (4.8) | |
| At first mammogram: | ||||
| Dense area, cm2 | 14.7 (4.5-30.3) | 12.0 (3.3-26.7) | 25.0 (14.4-38.0) | |
| Nondense area, cm2 | 116.0 (77.6-161.1) | 122.6 (85.6-170.7) | 83.2 (57.6-132.7) | |
| Total area, cm2 | 135.3 (100.6-179.7) | 139.3 (107.8-187.7) | 118.0 (82.1-162.5) | |
| Percent density, % | 11.7 (3.0-26.1) | 8.7 (2.3-21.8) | 24.1 (12.3-34.7) | |
| At last mammogram: | ||||
| Dense area, cm2 | 12.1 (3.5-25.7) | 9.7 (2.8-21.7) | 23.6 (11.4-36.6) | |
| Nondense area, cm2 | 131.0 (91.0-178.2) | 138.7 (99.6-186.7) | 93.7 (60.0-139.0) | |
| Total area, cm2 | 148.3 (110.4-195.6) | 154.3 (118.1-200.9) | 123.6 (83.8-165.9) | |
| Percent density, % | 8.5 (2.4-20.4) | 6.7 (1.6-16.7) | 21.2 (8.7-31.4) | |
| Difference between first and last mammogram | ||||
| Dense area, cm2 | -0.7 (-6.0-0.6) | -0.9 (-5.5-0.4) | -0.4 (-8.1-2.9) | |
| Nondense area, cm2 | 11.2 (0-27.9) | 13.1 (0-30.4) | 0.7 (-4.4-18.7) | |
| Total area, cm2 | 8.5 (-1.2-24.4) | 10.3 (-0.4-26.8) | 0.0 (-4.5-13.4) | |
| Percent density, % | -0.9 (-6.1-0.1) | -1.0 (-5.3-0.1) | -0.5 (-9.6-2.3) | |
| N (%) | ||||
|
|
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| Case-Control statusa | Cases | 155 (15) | 149 (18) | 6 (3) |
| Controls | 909 (85) | 697 (82) | 212 (97) | |
| Menarche | ≤12 | 382 (36) | 311 (37) | 71 (33) |
| 13+ | 680 (64) | 533 (63) | 147 (67) | |
| Parity | Nulliparous | 120 (11) | 107 (13) | 13 (6) |
| Multiparous | 908 (85) | 739 (87) | 169 (78) | |
| Family history (number of women) | Yes | 318 (37) | 149 (22) | 169 (100) |
| No | 541 (63) | 541 (78) | 0 (0) | |
a
Case-control status of participants refer to the status at selection of the nested case-control MD study