Table 3.

Mutually adjusted regression coefficients for established risk factors for mammographic density measured by the threshold and SMF methods in 250 women

Explanatory variableIncrement/categoryMean (SD) or percentage (%)Dense tissue
Percent density including edge
Percent density excluding edge
Threshold (area)SMF (volume)ThresholdSMFSMF
AgePer 1 y60.1 (2.61)−0.005 (−0.05, 0.04)−0.02 (−0.06, 0.02)−0.007 (−0.05, −0.04)−0.03 (−0.07, 0.02)−0.02 (−0.07, 0.02)



P = 0.84
P = 0.35
P = 0.76
P = 0.26
P = 0.31
BMIPer 2 kg/m2 increase26.9 (5.1)−0.05 (−0.10, 0.003)0.20 (0.16, 0.25)−0.15 (−0.20, −0.10)−0.07 (−0.12, −0.02)−0.10 (−0.15, −0.05)



P = 0.06
P < 0.001
P < 0.001
P = 0.006
P < 0.001
Parity1-2 (reference)30.6%00000
3-546.5%−0.16 (−0.43, 0.12)−0.25 (−0.50, −0.00)−0.19 (−0.45, 0.07)−0.45 (−0.73, −0.18)−0.42 (−0.69, −0.15)
P = 0.27P = 0.05P = 0.16P = 0.001P = 0.002
6+9.0%−0.42 (−0.89, 0.06)−0.63 (−1.05, −0.21)−0.40 (−0.84, 0.04)−0.83 (−1.30, −0.36)−0.66 (−1.12, −0.20)
P = 0.08P = 0.004P = 0.08P = 0.001P = 0.005
Nulliparous13.9%0.30 (−0.09, 0.68)−0.10 (−0.44, 0.25)0.37 (0.01, 0.73)0.09 (−0.29, 0.48)0.25 (−0.12, 0.63)



P = 0.13
P = 0.59
P = 0.04
P = 0.63
P = 0.18
HRTNo (reference)88.2%00000
Yes11.8%0.42 (0.04, 0.79)0.08 (−0.25, 0.42)0.44 (0.09, 0.79)0.25 (−0.12, 0.63)0.26 (−0.10, 0.63)
P = 0.03P = 0.63P = 0.02P = 0.19P = 0.16
  • NOTE: Effect of the explanatory variable on the standardized density measure (mean across the four values for each woman). Coefficients are the number of SDs change in mammographic density (or dense area/volume) associated with each explanatory variable.

    Abbreviation: HRT, hormone replacement therapy.