Table 1.
Characteristics of women who refused to participate vs. those willing to participate in the Radiological Evaluation And Breast Density (READ) study.
| Characteristics | Refused: | Willing to Participate | ||
|---|---|---|---|---|
| Unwilling to quit HT | Other reason | Overall | ||
| N = 1876 | N= 1292 | N = 3168 | N = 1535 | |
| Age at recruitment, mean (SD) | 60.9 (7.6)† | 61.7 (8.0)‡ | 61.3 (7.7)‡ | 60.4 (7.3) |
| Age at recruitment | ||||
| ≤ 55 years | 26.5 | 22.3 | 24.8 | 26.7 |
| 56–60 | 28.1 | 28.2 | 28.2 | 29.6 |
| 61–65 | 18.1 | 21.0 | 19.3 | 20.9 |
| 66–70 | 14.6 | 11.7 | 13.4 | 12.3 |
| 71+ | 12.8 | 16.9 | 14.5 | 10.6 |
| Race/ethnicity | ||||
| Caucasian | 91.5 | 87.8‡ | 90.0 | 91.4 |
| African American | 2.7 | 2.3 | 2.5 | 2.2 |
| Asian | 2.1 | 5.6 | 3.6 | 2.0 |
| Other | 3.6 | 4.4 | 3.9 | 4.5 |
| Hispanic | ||||
| Yes | 2.4 | 3.3 | 2.8 | 2.5 |
| Education | ||||
| ≤High school | 16.7 | 21.6‡ | 18.7† | 14.5 |
| Some college | 38.8 | 37.4 | 38.3 | 40.7 |
| College graduate | 20.3 | 18.8 | 19.7 | 19.7 |
| ≥Graduate school | 24.1 | 22.3 | 23.4 | 25.1 |
| Hysterectomy | ||||
| Yes | 50.8† | 52.4 | 51.4 | 54.3 |
| Type of hormone therapy | ||||
| Estrogen + progestin | 40.1 | 38.9 | 39.6 | 37.6 |
| Unopposed estrogen | 59.9 | 61.2 | 60.4 | 62.4 |
| Self-reported duration of HT use from BSRR at index mammogram | ||||
| ≤ 2 years | 9.3 | 9.3† | 9.3† | 10.3 |
| 3–4 years | 10.8 | 10.6 | 10.7 | 11.7 |
| 5–9 years | 23.5 | 19.7 | 21.9 | 22.7 |
| 10–14 years | 19.6 | 22.1 | 20.6 | 20.1 |
| 15+ years | 36.8 | 38.4 | 37.5 | 35.1 |
| Estrogen dose* | ||||
| Low | 24.8 | 22.2 | 23.8 | 25.3 |
| Medium | 58.7 | 63.4 | 60.6 | 62.5 |
| High | 16.5 | 14.4 | 15.6 | 12.2 |
| Body mass index in kg/m2, at index mammogram | ||||
| (mean, SD) | 27.0 (5.7)‡ | 27.2 (6.0) | 27.1 (5.8)‡ | 27.7 (5.7) |
| (median) | 25.8 | 25.9 | 25.8 | 26.6 |
| <25 | 42.3‡ | 42.7† | 42.4‡ | 37.5 |
| 25 to <30 | 32.9 | 28.8 | 31.2 | 33.1 |
| 30+ | 24.8 | 29.5 | 26.3 | 29.4 |
| Gail model risk score, lifetime | ||||
| <15% | 92.2 | 92.5 | 92.3 | 91.3 |
| 15 – <20% | 5.0 | 5.1 | 5.0 | 5.5 |
| 20 – <30% | 2.2 | 1.8 | 2.1 | 2.2 |
| ≥ 30% | 0.6 | 0.6 | 0.6 | 1.0 |
| First degree family history | ||||
| Yes | 18.1 | 16.8 | 17.6 | 18.2 |
| Mammographic breast density at index mammogram‡ | ||||
| Scattered fibroglandular | 34.0 | 34.4 | 34.2 | 34.8 |
| Heterogeneously dense | 56.0 | 56.4 | 56.1 | 55.2 |
| Extremely dense | 10.0 | 9.3 | 9.7 | 10.0 |
‡
p<0.01;
†
p<0.05, comparing group to women willing to participate
*
Estrogen dose: Medium = 0.0625 mg conjugated estrogens, 1 mg oral estradiol, 0.050 mg transdermal estradiol; Low = any doses < medium: High= any doses > medium.