Table 1.
Descriptive Characteristics of Participants at Baseline by Randomization Group
| Characteristic | Estrogen Plus Progestin (n = 8506) | Placebo (n = 8102) |
|---|---|---|
| Age at Screening | ||
| 50–59 years | 2837/8506 (33.4) | 2383/8102 (33.1) |
| 60–69 years | 3854/8506 (45.3) | 3655/8102 (45.1) |
| 70–79 years | 1815/8506 (21.3) | 1764/8102 (21.8) |
| Race/Ethnicity | ||
| White | 7141/8506 (84.0) | 6805/8102 (84.0) |
| Black | 548/8506 (6.4) | 574/8102 (7.1) |
| Hispanic | 471/8506 (5.5) | 415/8102 (5.1) |
| American Indian | 25/8506 (3.3) | 30/8102 (0.4) |
| Asian/Pacific Islander | 194/8506 (2.3) | 169/8102 (2.1) |
| Unknown | 127/8506 (1.5) | 109/8102 (1.3) |
| Body Mass Index | ||
| <25 kg/m2 | 1110/8506 (21.0) | 1096/8102 (20.3) |
| 25 to <30 kg/m2 | 1798/8506 (34.0) | 1915/8102 (35.5) |
| 30 kg/m2 | 2375/8506 (45.0) | 2385/8102 (44.2) |
| Prior Estrogen-Only Use | ||
| No | 7603/8506 (89.4) | 7237/8102 (89.3) |
| Yes | 903/8506 (10.6) | 864/8102 (10.7) |
| <5 years | 677/8506 (8.0) | 659/8102 (8.1) |
| 5 to <10 years | 134/8506 (1.6) | 109/8102 (1.3) |
| >10 years | 92/8506 (1.1) | 96/8102 (1.2) |
| Prior Estrogen Plus Progestin Use | ||
| No | 6990/8506 (82.2) | 6706/8102 (82.8) |
| Yes | 1516/8506 (17.8) | 1396/8102 (17.2) |
| <5 years | 1050/8506 (12.3) | 997/8102 (12.3) |
| 5 to <10 years | 315/8506 (3.7) | 258/8102 (3.2) |
| >10 years | 151/8506 (1.8) | 141/8102 (1.7) |
| Recent Hormone Use | ||
| No | 6277/8506 (73.8) | 6020/8102 (74.3) |
| Past <5 years | 727/8506 (8.6) | 679/8102 (8.4) |
| Past 5 to <10 years | 335/8506 (3.9) | 310/8102 (3.8) |
| Past >10 years | 609/8506 (7.2) | 599/8102 (7.4) |
| Current (3-month washout) | 554/8506 (6.5) | 491/8102 (6.1) |
| Oral Contraceptive Use (Ever) | 3695/8506 (43.3) | 3447/8102 (42.5) |
| Years Since Menopause | ||
| <10 years | 827/8506 (19.0) | 817/8102 (18.3) |
| 10–19 years | 1292/8506 (29.7) | 1333/8102 (29.8) |
| >20 years | 2230/8506 (51.3) | 2319/8102 (51.9) |
| Tobacco Exposure | ||
| Smoking Status | ||
| Never | 4178/8420 (49.6) | 3999/7994 (50.0) |
| Past | 3362/8420 (39.9) | 3157/7994 (39.5) |
| Current | 880/8420 (10.5) | 838/7994 (10.5) |
| No. of Cigarettes per Day | ||
| <25 | 3345/4097 (81.6) | 3175/3873 (82.0) |
| >25 | 752/4097 (18.4) | 698/3873 (18.0) |
| Years Smoked | ||
| <30 | 2563/4109 (62.4) | 2422/3912 (61.9) |
| >30 | 1546/4109 (37.6) | 1490/3912 (38.1) |
| Pack-Years of Smoking | ||
| Never smoker | 4178/8228 (50.8) | 3999/7822 (51.1) |
| <5 | 1119/8228 (13.6) | 1004/7822 (12.8) |
| 5 to <20 | 1168/8228 (14.2) | 1140/7822 (14.6) |
| >20 | 1763/8228 (21.4) | 1679/7822 (21.5) |
| Lung cancer (>10 years prior) | 3/8435 (<0.1) | 2/8036 (<0.1) |
Because of rounding, percentages might not all total 100. Includes 331 women previously randomized to estrogen-alone group who were reassigned to estrogen plus progestin group after protocol change, as previously described. For current users, 3-month washout period required before entry. Current and previous smokers were combined when estimating total number of cigarettes per day, years smoked, and past years of smoking.