Table 1.
Baseline Demographics and Clinical Characteristics of Women's Health Initiative Participants According to Use of Oral Bisphosphonates (1993 to 2010)
| Characteristic | Oral Bisphosphonate User |
|||||||
|---|---|---|---|---|---|---|---|---|
| At Baseline |
At Baseline, Year 1, or Year 3* |
|||||||
| No (n = 88,073) |
Yes (n = 1,845) |
No (n = 76,993) |
Yes (n = 6,293) |
|||||
| No. | % | No. | % | No. | % | No. | % | |
| Age at eligibility screening, years | ||||||||
| Mean | 62.9 | 67.2 | 62.8 | 66.1 | ||||
| SD | 7.2 | 6.4 | 7.1 | 6.6 | ||||
| 50-59 | 31,084 | 35.3 | 229 | 12.4 | 27,627 | 35.9 | 1,091 | 17.3 |
| 60-69 | 39,009 | 44.3 | 887 | 48.1 | 34,119 | 44.3 | 3,144 | 50.0 |
| ≥ 70 | 17,980 | 20.4 | 729 | 39.5 | 15,247 | 19.8 | 2,058 | 32.7 |
| Race/ethnicity | ||||||||
| White | 74,459 | 85.7 | 1,671 | 91.5 | 65,447 | 86.2 | 5,700 | 91.8 |
| Black/African American | 6,177 | 7.1 | 19 | 1.0 | 5,286 | 7.0 | 101 | 1.6 |
| Hispanic/Latino | 3,354 | 3.9 | 40 | 2.2 | 2,780 | 3.7 | 113 | 1.8 |
| Asian/Pacific Islander | 2,536 | 2.9 | 97 | 5.3 | 2160 | 2.8 | 290 | 4.7 |
| American Indian/Alaskan native | 319 | 0.4 | 0 | 0.0 | 269 | 0.4 | 6 | 0.1 |
| Other/missing | 1,228 | — | 18 | — | 1,051 | — | 83 | — |
| Education | ||||||||
| Less than high school | 3,998 | 4.6 | 59 | 3.2 | 3,345 | 4.4 | 179 | 2.9 |
| High school/vocational | 22,129 | 25.3 | 425 | 23.2 | 19,428 | 25.4 | 1,433 | 23.0 |
| Some college | 23,097 | 26.4 | 398 | 21.7 | 20,157 | 26.4 | 1,475 | 23.6 |
| College | 10,561 | 12.1 | 278 | 15.2 | 9,305 | 12.2 | 868 | 13.9 |
| Graduate/professional | 27,656 | 31.6 | 671 | 36.6 | 24,233 | 31.7 | 2,285 | 36.6 |
| Missing | 632 | — | 14 | — | 525 | — | 53 | — |
| Body mass index, kg/m2 | ||||||||
| Mean | 27.6 | 25.1 | 27.7 | 25.1 | ||||
| SD | 5.9 | 4.8 | 5.8 | 4.6 | ||||
| < 25 | 32,749 | 37.2 | 1,052 | 57.0 | 28,160 | 36.6 | 3,549 | 56.4 |
| 25 to < 30 | 29,939 | 34.0 | 562 | 30.5 | 26,343 | 34.2 | 1,939 | 30.8 |
| ≥ 30 | 24,576 | 27.9 | 222 | 12.0 | 21,794 | 28.3 | 753 | 12.0 |
| Missing | 809 | — | 9 | — | 696 | — | 52 | — |
| Smoking | ||||||||
| Never | 43,833 | 50.4 | 990 | 54.3 | 38,564 | 50.7 | 3,309 | 53.3 |
| Former | 36,961 | 42.5 | 747 | 41.0 | 32,291 | 42.5 | 2,584 | 41.6 |
| Current | 6,145 | 7.1 | 85 | 4.7 | 5,195 | 6.8 | 316 | 5.1 |
| Missing | 1,134 | — | 23 | — | 943 | — | 84 | — |
| Parity, No. of children | ||||||||
| Nulliparous | 11,131 | 12.7 | 284 | 15.5 | 9,639 | 12.6 | 906 | 14.5 |
| 1 | 7,718 | 8.8 | 148 | 8.1 | 6,658 | 8.7 | 512 | 8.2 |
| 2 | 22,040 | 25.2 | 472 | 25.7 | 19,245 | 25.2 | 1,625 | 25.9 |
| 3 | 21,026 | 24.0 | 434 | 23.7 | 18,464 | 24.1 | 1,539 | 24.6 |
| ≥ 4 | 25,598 | 29.3 | 497 | 27.1 | 22,514 | 29.4 | 1,681 | 26.8 |
| Missing | 560 | — | 10 | — | 473 | — | 30 | — |
| Mammography in prior 2 years | ||||||||
| No | 14,929 | 17.5 | 152 | 8.5 | 12,966 | 17.4 | 617 | 10.1 |
| Yes | 70,410 | 82.5 | 1,644 | 91.5 | 61,739 | 82.6 | 5,503 | 89.9 |
| Missing | 2,734 | — | 49 | — | 2,288 | — | 173 | — |
| Oral contraceptive use | ||||||||
| Never | 50,407 | 57.3 | 1,281 | 69.4 | 43,446 | 56.4 | 4,182 | 66.5 |
| < 1 year | 7,658 | 8.7 | 127 | 6.9 | 6,769 | 8.8 | 479 | 7.6 |
| 1 to < 3 years | 7,865 | 8.9 | 129 | 7.0 | 6,972 | 9.1 | 452 | 7.2 |
| ≥ 3 years | 22,115 | 25.1 | 308 | 16.7 | 19,784 | 25.7 | 1,180 | 18.8 |
| Missing | 28 | — | 0 | — | 22 | — | 0 | — |
| E-alone use | ||||||||
| Never | 77,834 | 88.4 | 1,593 | 86.3 | 68,091 | 88.4 | 5,445 | 86.5 |
| < 5 years | 6,714 | 7.6 | 167 | 9.1 | 5,820 | 7.6 | 585 | 9.3 |
| 5 to < 10 years | 1,763 | 2.0 | 44 | 2.4 | 1,551 | 2.0 | 129 | 2.0 |
| ≥ 10 years | 1,761 | 2.0 | 41 | 2.2 | 1,530 | 2.0 | 134 | 2.1 |
| Missing | 1 | — | 0 | — | 1 | — | 0 | — |
| E+P use | ||||||||
| Never | 54,057 | 61.4 | 1,162 | 63.0 | 46,709 | 60.7 | 4,001 | 63.6 |
| < 5 years | 17,097 | 19.4 | 353 | 19.1 | 15,154 | 19.7 | 1,134 | 18.0 |
| 5 to < 10 years | 9,418 | 10.7 | 152 | 8.2 | 8,451 | 11.0 | 587 | 9.3 |
| ≥ 10 years | 7,500 | 8.5 | 178 | 9.6 | 6,678 | 8.7 | 571 | 9.1 |
| Missing | 1 | — | 0 | — | 1 | — | 0 | — |
| 5-Year predicted probability of hip fracture, %† | ||||||||
| < 0.5 | 63,449 | 72.0 | 757 | 41.0 | 56,157 | 72.9 | 3,213 | 51.1 |
| 0.5 to 1 | 13,334 | 15.1 | 481 | 26.1 | 11,511 | 15.0 | 1,459 | 23.2 |
| ≥ 1 | 11,290 | 12.8 | 607 | 32.9 | 9,325 | 12.1 | 1,621 | 25.8 |
| Missing | 0 | — | 0 | — | 0 | — | 0 | — |
| Women's Health Initiative study components‡ | ||||||||
| Observational study | 49,349 | 56.0 | 1,308 | 70.9 | 42,587 | 55.3 | 4,145 | 65.9 |
| Calcium/vitamin D CT | 20,844 | 23.7 | 226 | 12.2 | 19,211 | 25.0 | 1,008 | 16.0 |
| Dietary modification CT | 26,999 | 30.7 | 364 | 19.7 | 23,873 | 31.0 | 1,491 | 23.7 |
| Hormone CT | 16,329 | 18.5 | 200 | 10.8 | 14,670 | 19.1 | 818 | 13.0 |
| Hormone CT arm | ||||||||
| Not included in hormone CT | 71,744 | 81.5 | 1,645 | 89.2 | 62,323 | 80.9 | 5,475 | 87.0 |
| Placebo | 7,960 | 9.0 | 105 | 5.7 | 7,076 | 9.2 | 479 | 7.6 |
| E+P | 8,369 | 9.5 | 95 | 5.1 | 7,594 | 9.9 | 339 | 5.4 |
Abbreviations: CT, clinical trial; E, estrogen; E+P, estrogen plus progestin; SD, standard deviation.
*
Among those remaining at risk of endometrial cancer at year 3.
†
Calculated as described in Robbins et al.18
‡
Percentages do not sum to 100% as a result of overlap of study components.