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Table 1 Agreement between the first and second measures using the Wolfe classification

From: Evaluation of mammographic density patterns: reproducibility and concordance among scales

Number of mammograms classified in each category in the first and second measurements
  Second measure
First measure N1 P1 P2 DY Total
N1 12 9 0 0 21
P1 4 139 13 5 161
P2 0 7 101 14 122
DY 0 2 13 56 71
Total 16 157 127 75 375
Kappa-statistic estimation
Agreement Kappa (95% CI) Weighted Kappa (95% CI) Kappa high/low risk (95% CI)  
Observed % Expected %     
82.13 33.02 0.733 (0.674-0.789) 0.835 (0.784-0.876) 0.851 (0.798-0.904)  
  1. Low risk categories:
  2. N1: Breast composed almost completely of fat, with perhaps just a few fibrous connective tissue strands.
  3. P1: Breast composed mainly of fat, although up to a quarter of the sub-areolar area may show beaded or cord-like areas corresponding to prominent ducts.
  4. High risk categories:
  5. P2: More severe involvement of the breast, with a prominent duct pattern occupying more than one quarter of breast volume.
  6. DY: Breast typically contains extensive regions of homogeneous mammographic densities, which appear as sheet-like regions. The proportion of density is greater than that of the fat.