TABLE 1.
Baseline characteristics by calibrated protein intake (calibrated percentage of calories from protein) in the WHI (n = 144,580)1
| Characteristic | Quintile 1 (<13.3%) | Quintile 3 (14.2–14.8%) | Quintile 5 (≥15.6%) |
| Age (y) | 66.0 ± 7.22 | 63.7 ± 6.9 | 59.6 ± 6.4 |
| BMI | |||
| Underweight (<18.5 kg/m2) | 262 (0.9) | 200 (0.7) | 332 (1.1) |
| Normal (18.5–24.9 kg/m2) | 8250 (28.7) | 9656 (33.7) | 12,357 (42.5) |
| Overweight (25.0–29.9 kg/m2) | 9481 (33.0) | 10,057 (35.0) | 10,242 (35.3) |
| Obese (≥30 kg/m2) | 10,780 (37.5) | 8781 (30.6) | 6121 (21.1) |
| Ethnicity | |||
| White | 22,283 (77.2) | 24,308 (84.7) | 24,725 (85.1) |
| Black | 4149 (14.4) | 2128 (7.4) | 1731 (6.0) |
| Hispanic | 1110 (3.9) | 981 (3.4) | 1189 (4.1) |
| American Indian | 157 (0.5) | 99 (0.3) | 116 (0.4) |
| Asian/Pacific Islander | 676 (2.3) | 781 (2.7) | 902 (3.1) |
| Unknown | 458 (1.6) | 397 (1.4) | 389 (1.3) |
| Family history of fracture | 9834 (34.2) | 10,657 (37.1) | 11,162 (38.4) |
| History of fracture (at age ≥55 y) | 4473 (15.5) | 3778 (13.2) | 2498 (8.6) |
| Calibrated energy intake (kcal)3 | 2122 ± 233 | 2143 ± 214 | 2143 ± 171 |
| Physical activity (METs/wk) | 9.9 ± 12.6 | 12.6 ± 13.6 | 15.0 ± 14.9 |
| Smoking | |||
| Never | 12,116 (42.1) | 15,368 (53.6) | 15,538 (53.5) |
| Past | 10,050 (34.9) | 12,544 (43.7) | 13,364 (46.0) |
| Current | 6607 (23.0) | 782 (2.7) | 150 (0.5) |
| Hormone use | |||
| Never | 14,687 (51.0) | 12,244 (42.7) | 10,903 (37.5) |
| Past | 5083 (17.7) | 4519 (15.7) | 4092 (14.1) |
| Current | 8981 (31.2) | 11,902 (41.5) | 14,033 (48.3) |
| Corticosteroid use | 299 (1.0) | 227 (0.8) | 200 (0.7) |
| Glucocorticoid use | 294 (1.0) | 215 (0.8) | 199 (0.7) |
| General health status | |||
| Excellent/very good | 14,309 (49.7) | 16,891 (58.9) | 19,226 (66.2) |
| Good | 10,868 (37.8) | 9466 (33.0) | 7942 (27.3) |
| Fair/poor | 3596 (12.5) | 2337 (8.1) | 1884 (6.5) |
| Medical history | |||
| Arthritis | 15,199 (52.8) | 13,823 (48.2) | 11,718 (40.3) |
| Rheumatoid arthritis | 1791 (6.2) | 1412 (4.9) | 1155 (4.0) |
| Diabetes (treated with pills or shots) | 1176 (4.1) | 1287 (4.5) | 1299 (4.5) |
1
P < 0.0001 for all baseline characteristics across quintiles of calibrated protein intake. P-value testing did not include participants who were not randomly assigned to the trial. MET, metabolic task hours; WHI, Women's Health Initiative.
2
Mean ± SD (all such values).
3
All values are geometric means ± SDs, because calibrated energy was back-transformed from the log scale.