Table 1.
Baseline characteristics of WHI trial of oestrogen-alone participants who consented to extended follow-up by randomised treatment assignment.
| Oestrogen | Placebo | |||
|---|---|---|---|---|
| N | % | N | % | |
| Age group at screening | ||||
| 50–59 | 1223 | 32·4 | 1232 | 31·9 |
| 60–69 | 1740 | 46·1 | 1799 | 46·5 |
| 70–79 | 815 | 21·6 | 836 | 21·6 |
| Race/ethnicity | ||||
| White | 2945 | 78·0 | 3001 | 77·6 |
| Black | 514 | 13·6 | 565 | 14·6 |
| Hispanic | 189 | 5·0 | 181 | 4·7 |
| American Indian | 31 | 0·8 | 18 | 0·5 |
| Asian/Pacific Islander | 54 | 1·4 | 49 | 1·3 |
| Unknown | 45 | 1·2 | 53 | 1·4 |
| Education | ||||
| ≤ High school/GED | 1167 | 31·2 | 1137 | 29·6 |
| Post-high school | 1630 | 43·6 | 1704 | 44·4 |
| College degree or higher | 945 | 25·3 | 998 | 26·0 |
| Family income ($) | ||||
| <20K | 891 | 24·8 | 913 | 24·9 |
| 20–<35K | 1070 | 29·8 | 1084 | 29·6 |
| 35–<50K | 741 | 20·6 | 758 | 20·7 |
| 50–<75K | 550 | 15·3 | 555 | 15·2 |
| ≥75K | 340 | 9·5 | 352 | 9·6 |
| Marital status | ||||
| Never married | 123 | 3·3 | 111 | 2·9 |
| Divorced / Separated | 709 | 18·8 | 687 | 17·9 |
| Widowed | 777 | 20·7 | 785 | 20·4 |
| Presently married/Living as married | 2153 | 57·2 | 2264 | 58·9 |
| Body-mass index (kg/m2) | ||||
| <25 | 785 | 20·9 | 771 | 20·1 |
| 25 – <30 | 1289 | 34·3 | 1391 | 36·2 |
| ≥30 | 1687 | 44·9 | 1683 | 43·8 |
| Smoking status | ||||
| Never | 1988 | 53·1 | 1972 | 51·5 |
| Past | 1417 | 37·9 | 1489 | 38·9 |
| Current | 336 | 9·0 | 370 | 9·7 |
| Age at menarche | ||||
| ≤11 | 890 | 23·7 | 929 | 24·1 |
| 12–13 | 2030 | 54·1 | 2013 | 52·3 |
| ≥14 | 833 | 22·2 | 908 | 23·6 |
| Number of term pregnancies | ||||
| Never pregnant/No term pregnancy | 350 | 9·3 | 307 | 8·0 |
| 1–2 | 1033 | 27·5 | 1099 | 28·6 |
| 3–4 | 1527 | 40·7 | 1605 | 41·7 |
| ≥5 | 840 | 22·4 | 835 | 21·7 |
| Age at first birth, years | ||||
| Never pregnant/No term pregnancy | 350 | 10·3 | 307 | 8·8 |
| <20 | 822 | 24·2 | 872 | 24·9 |
| 20 – 29 | 2060 | 60·7 | 2128 | 60·9 |
| 30+ | 163 | 4·8 | 190 | 5·4 |
| Number of months breastfed | ||||
| Never breastfed | 1775 | 47·8 | 1739 | 45·8 |
| Breastfed ≤1 year | 1412 | 38·0 | 1525 | 40·1 |
| Breastfed >1 year | 525 | 14·1 | 535 | 14·1 |
| Benign breast disease | ||||
| No | 2758 | 80·2 | 2693 | 77·7 |
| Yes, 1 biopsy | 500 | 14·5 | 550 | 15·9 |
| Yes, 2+ biopsies | 183 | 5·3 | 222 | 6·4 |
| First degree female relatives with breast cancer | ||||
| None | 2987 | 85·5 | 3084 | 86·0 |
| 1 | 459 | 13·1 | 453 | 12·6 |
| 2 or more | 48 | 1·4 | 49 | 1·4 |
| Gail model 5-year risk score, | ||||
| <1.25% | 1456 | 38·5 | 1505 | 38·9 |
| [1.25%, 1.75%) | 1185 | 31·4 | 1220 | 31·5 |
| ≥1.75% | 1137 | 30·1 | 1142 | 29·5 |
| Age at hysterectomy | ||||
| <40 | 1495 | 39·8 | 1501 | 39·0 |
| 40–49 | 1643 | 43·7 | 1662 | 43·2 |
| 50–54 | 345 | 9·2 | 412 | 10·7 |
| 55+ | 275 | 7·3 | 271 | 7·0 |
| Bilateral oophorectomy | ||||
| No | 2143 | 61·0 | 2094 | 58·2 |
| Yes | 1370 | 39·0 | 1507 | 41·8 |
| Years since menopause | ||||
| <10 | 636 | 19·9 | 623 | 18·8 |
| 10 - <20 years | 1025 | 32·1 | 1104 | 33·3 |
| ≥20 | 1535 | 48·0 | 1586 | 47·9 |
| Hormone therapy use | ||||
| Never | 1929 | 51·1 | 1916 | 49·6 |
| Past | 1304 | 34·5 | 1373 | 35·5 |
| Current | 544 | 14·4 | 575 | 14·9 |
| Unopposed oestrogen use | ||||
| Non-user | 2006 | 53·1 | 2007 | 51·9 |
| <5 years | 938 | 24·8 | 1008 | 26·1 |
| ≥5 years | 834 | 22·1 | 852 | 22·0 |
| Oestrogen + Progestin use | ||||
| Non-user | 3613 | 95·6 | 3668 | 94·9 |
| <5 years | 108 | 2·9 | 123 | 3·2 |
| ≥5 years | 57 | 1·5 | 76 | 2·0 |