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Table 1 Demographic and risk factor distributionsa of the Mayo Mammography Health Study cohort (2003 to 2006)

From: The influence of mammogram acquisition on the mammographic density and breast cancer association in the mayo mammography health study cohort

  Analysis groups  
  Cases, Mean or N (SD/%)b Subcohort, Mean or N (SD/%) Eligible cohort, Mean or N (SD/%)
Number 318 2,259 19,865c
Age, years 61.8 (11.2) 58.0 (12.2) 58.0 (12.2)
Body mass index, kg/m2 28.9 (6.9) 28.1 (6.5) 28.2 (6.4)
Post-menopausal hormone use    
   Current 61 (19.2%) 445 (19.4%) 3,554 (17.9%)
   Former 85 (26.7%) 505 (22.0%) 4,561 (23.0%)
   Never 148 (46.5%) 1,143 (49.7%) 9,986 (50.3%)
   Unknown 24 (7.6%) 205 (8.9%) 1,764 (8.9%)
Post-menopausal 252 (79.3%) 1,592 (69.3%) 13,627 (68.6%)
Imaging parameters    
   Number 254 1,910  
   Percent density 19.1 (13.7) 17.6 (14.1)  
   Dense area, mm2 2,622 (1,939) 2,333 (1,841)  
   Non-dense area, mm2 13,232 (6,702) 13,460 (7,198)  
   Milliampere-seconds 161.0 (49.4) 157.9 (49.5)  
   X-ray tube voltage peak, kVp 26.2 (1.7) 26.1 (1.5)  
   Thickness, mm 53.9 (13.3) 53.2 (12.7)  
   Compression force, pounds 24.7 (6.1) 24.9 (5.6)  
  1. aReported at enrollment; b39 women overlap between cases and subcohort; c59 women were deleted for breast cancers occurring within the first two months after enrollment. They are included in the full cohort but excluded from analyses in this paper. SD, standard deviation.