Table 1.
Characteristics of study participants compared with the SWAN bone cohort at baseline
| Characteristics | Study Sample (N=1919) | SWAN bone cohort (N=2413) |
|---|---|---|
| Age (year) | 45.9±2.7 | 45.8±2.7 |
| Race | ||
| Caucasian | 960 (50.0%) | 1196 (49.6%) |
| African American | 502 (26.2%) | 686 (28.4%) |
| Chinese | 220 (11.5%) | 250 (10.4%) |
| Japanese | 237 (12.4%) | 281 (11.7%) |
| Body Mass Index (kg/m2) | 27.5±6.9 | 28.0±7.5 |
| Menopause status | ||
| Premenopausal | 1085 (56.5%) | 1288 (54.1%) |
| Early perimenopausal | 834(43.5%) | 1094(45.9%) |
| Smoking status | ||
| Current | 283 (14.7%) | 393 (16.4%) |
| Ex-smoker | 485 (25.3%) | 619 (25.9%) |
| Never smoked* | 1151 (60.0%) | 1383 (57.8%) |
| Smoking (Pack-year) | ||
| 0 | 1246 (64.9%) | 1526 (63.2%) |
| ≤10 years | 304 (15.8%) | 377 (15.6%) |
| >10 ≤ 30 years | 292 (15.2%) | 389 (16.1%) |
| ≥30 years | 77 (4.0%) | 121 (5.0%) |
| Alcohol consumption | ||
| Abstainer | 990 (51.6%) | 1244 (51.8%) |
| Infrequent | 179 (9.3%) | 220 (9.2%) |
| Light to moderate | 489 (25.5%) | 607 (25.3%) |
| Heavy | 261 (13.6%) | 332 (13.8%) |
| Use of supplementary calcium | 862 (45.0%) | 1066 (44.5%) |
| Use of supplementary Vitamin D | 741 (38.6%) | 917 (38.2%) |
| Use of bone-adverse medications** | 44 (2.3%) | 56 (2.3%) |
| Prior use of any sex steroid hormones | 127 (6.6%) | 179 (7.4%) |
| Prior use of depo-provera injections | 14 (0.7%) | 20 (0.8%) |
| History of hyperthyroidism | 70 (3.7%) | 89 (3.7%) |
| History of previous adult fracture | 352 (18.3%) | 457 (18.9%) |
| Employment Status | 1581 (82.4%) | 1977 (82.0%) |
| Femoral neck bone mineral density (g/cm2) | 0.84±0.13 | 0.85±0.14**** |
| Compression strength index (g/kg-m) | 3.31±0.64 | - |
| Bending strength index (g/kg-m) | 1.02±0.22 | - |
| Impact strength index (g/kg-m) | 0.18±0.04 | - |
| Sport Activity Score | 2.71±1.02 | 2.69±1.03 |
| Home Activity Score | 2.69±0.83 | 2.70±0.85 |
| Active Living Score | 2.36±0.78 | 2.36±0.79 |
| Work Activity Score*** | 1.99±0.80 | 2.00±0.81 |
| Total Physical Activity Score | 9.76±1.95 | 9.75±2.00 |
Note: For continuous variables, mean and standard deviation are shown. For categorical variables, number and percentage are shown.
*
13 women who were missingsmoking status answered 0 for pack years, so we assigned them to the never-smoked group.
**
Bone-adverse medications included oral steroid and anti-epileptics. At baseline, no one took chemotherapy or aromatase-inhibitors.
***
Unemployed women were assigned 1 for the work activity score.
****
There were a total of 2413 women in five SWAN bone sites, but only 2328 women had femoral neck bone scans at baseline.