Baseline characteristics of participants in NHS, NHS II, HPFS and WHI cohorts
| Characteristic | Discovery cohorts | Replication cohorts | ||
| NHS (N=6792) | NHS II (N=3168) | HPFS (N=2178) | WHI (N=1866) | |
| Age, years | 56.8 (6.8) | 44.6 (4.5) | 63.5 (8.3) | 66.9 (6.9) |
| White | 96.1% | 97.1% | 98.3% | 78.8% |
| Black | 3.3% | 1.2% | 0.2% | 13.6% |
| Hispanic | 0.9% | 1.1% | – | 2.6% |
| Asian or Pacific Islander | 0.5% | 1.3% | 0.2% | 1.9% |
| Native American | 0.1% | 0.2% | – | 0.6% |
| Other | 0.2% | 0.3% | 1.2% | 2.5% |
| BMI, kg/m2 | 25.5 (4.6) | 25.6 (5.4) | 25.6 (3.0) | 28.3 (5.9) |
| Never smoker, % | 46.6% | 67.1% | 49.6% | 49.4% |
| Alcohol, g/day | 5.9 (10.4) | 3.5 (6.4) | 11.3 (14.8) | 4.9 (11.4) |
| AHEI dietary score | 47.4 (9.9) | 45.8 (10.1) | 49.1 (11.0) | 47.0 (9.7) |
| Physical activity, MET-hours/week | 16.0 (22.5) | 18.1 (22.0) | 32.4 (29.1) | 11.4 (13.0) |
| Thiazide use, % | 13.4% | 3.8% | 4.0% | 6.0% |
| Menopausal hormone therapy use, % | 31.8% | 11.0% | – | 47.8% |
| Premenopausal | 19.5% | 75.1% | – | 0.0% |
| Parity, % | 92.9% | 82.6% | – | 88.4% |
| Fasting at sample collection, % | 74.6% | 71.3% | 60.0% | 99.6% |
| Incident gallstone cases, N | 1200 (17.7%) | 385 (12.2%) | 170 (7.8%) | 169 (9.1%) |
| Time to event, years | 10.5 (7.9) | 9.1 (5.8) | 10.6 (6.9) | 4.7 (2.5) |
| Follow-up time, years | 25.4 (7.0) | 22.2 (3.5) | 19.6 (7.8) | 7.4 (2.0) |
AHEI, Alternative Healthy Eating Index-2010 score; BMI, body mass index; HPFS, Health Professionals Follow-up Study; NHS, Nurses’ Health Study; WHI, Women’s Health Initiative.