Table 5.

Multivariable regression analysis (generalized estimating equation) to determine effect of various risk factors on mammographic density after adjustment for twin status (n = 1,106)

VariablePercent density
Absolute density
βSEP*βSEP*
Age at mammogram−0.230.130.072−0.180.170.28
BMI−1.570.10<0.0001−0.640.15<0.0001
Parous (y/n)−4.251.450.003−2.662.170.22
Number of additional births−0.990.410.016−1.020.550.063
Age at menarche0.890.470.0600.170.630.79
Menopausal status/current HT use
    Premenopausal, no current HT useReferenceReference
    Postmenopausal, not current HT user−6.741.760.0001−9.582.38<0.0001
    Postmenopausal, current HT user−5.751.34<0.0001−7.581.89<0.0001
    Unknown−1.032.000.61−2.292.870.43
  • * P values are based on Z test in the generalized estimating equation model.