Table 1 Descriptive characteristics of study population (n = 1121) at the time of mammography, Nurses' Health Study (1989–1998)
From: Breast cancer susceptibility loci and mammographic density
Characteristic | Â | Â |
|---|---|---|
Mean values | Mean | SD |
Age, y | 58.4 | 7.3 |
Body mass index, kg/m2 | 25.6 | 4.6 |
Percentage mammographic density, % | 27.1 | 20.6 |
Frequencies a | N | % |
Menopausal/hormone status | Â | Â |
   Premenopausal | 217 | 19.4 |
   Postmenopausal/never user | 371 | 33.1 |
   Postmenopausal/past user | 317 | 28.3 |
   Postmenopausal/current user | 216 | 19.3 |
Alcohol consumption | Â | Â |
   None | 327 | 31.8 |
   <5 g/day | 346 | 33.6 |
   5 to 14.9 g/day | 221 | 21.5 |
   15+ g/day | 135 | 13.1 |
Parity/age at first birth | Â | Â |
   Nulliparous | 83 | 7.5 |
   Parous/<25 years | 549 | 49.6 |
   Parous/25 to 29 years | 382 | 34.5 |
   Parous/>30 | 93 | 8.4 |
Prior benign breast disease | 465 | 41.5 |
Family history of breast cancer | 135 | 12.0 |