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Table 4 Difference in adult mammographic density parameters across categories of age at onset of pubertal stages

From: Childhood body size and pubertal timing in relation to adult mammographic density phenotype

   Mammographic density parameters
    Absolute area
   Percent density difference, Dense area Non-dense area
Age at pubertal stage Category percentage points (95% CI)a difference, cm2 (95% CI)a difference, cm2 (95% CI)a
Age at thelarche, years
 A: ≤10 0.0 (baseline) 0.0 (baseline) 0.0 (baseline)
11–12 2.6 (-1.2-6.7) 0.8 (-3.6, 5.5) -8.8 (-19.3, 2.4)
≥13 5.7 (1.6-10.1) 1.7 (-2.8, 6.6) -23.1 (-33.1, -12.5)
P trendb 0.002 0.42 <0.001
 B: +BMI-adjusted ≤10 0.0 (baseline) 0.0 (baseline) 0.0 (baseline)
11–12 1.0 (-2.4, 4.6) 0.0 (-4.2, 4.6) -3.7 (-12.2, 5.1)
≥13 2.2 (-1.4, 6.0) -0.1 (-4.5, 4.6) -11.7 (-20.1, -3.0)
P trendb 0.20 0.95 0.002
 C: +weight age 11 years ≤10 0.0 (baseline) 0.0 (baseline) 0.0 (baseline)
11–12 0.2 (-3.1, 3.8) -1.0 (-5.1, 3.5) -3.0 (-11.5, 5.9)
≥13 0.3 (-3.3, 4.1) -2.5 (-6.8, 2.2) -10.0 (-18.8, -0.7)
P trendb 0.88 0.24 0.012
Age at menarche, years
 A: ≤12 0.0 (baseline) 0.0 (baseline) 0.0 (baseline)
13–14 4.7 (2.1, 7.3) 3.5 (0.6, 6.6) -12.7 (-19.5, -5.7)
≥15 6.9 (2.7, 11.3) 5.7 (1.0, 10.8) -17.7 (-28.1, -6.8)
P trendb <0.001 0.003 <0.001
 B: +BMI-adjusted ≤12 0.0 (baseline) 0.0 (baseline) 0.0 (baseline)
13–14 2.9 (0.6, 5.2) 2.9 (0.0, 5.9) -5.2 (-10.8, 0.6)
≥15 3.2 (-0.4, 7.1) 4.2 (-0.4, 9.1) -3.1 (-12.1, 6.2)
P trendb 0.014 0.023 0.18
 C: +weight age 11 years ≤12 0.0 (baseline) 0.0 (baseline) 0.0 (baseline)
13–14 2.0 (-0.3, 4.4) 1.7 (-1.1, 4.7) -4.0 (-9.8, 1.9)
≥15 1.8 (-1.8, 5.6) 2.3 (-2.2, 7.1) -1.4 (-10.6, 8.2)
P trendb 0.13 0.20 0.40
Age at regular cycles, years
 A: ≤12 0.0 (baseline) 0.0 (baseline) 0.0 (baseline)
13–14 5.2 (1.9, 8.7) 5.4 (1.3, 9.7) -10.0 (-18.8, -0.8)
≥15 6.4 (2.5, 10.5) 5.3 (0.7, 10.3) -12.4 (-22.4, -2.0)
P trendb <0.001 0.013 0.014
 B: +BMI-adjusted ≤12 0.0 (baseline) 0.0 (baseline) 0.0 (baseline)
13–14 3.3 (0.3, 6.5) 4.6 (0.6, 8.8) -2.2 (-9.8, 5.6)
≥15 4.3 (0.8, 8.1) 4.4 (-0.1, 9.2) -4.3 (-12.8, 4.5)
P trendb 0.010 0.036 0.33
 C: +weight age 11 years ≤12 0.0 (baseline) 0.0 (baseline) 0.0 (baseline)
13–14 2.5 (-0.6, 5.7) 3.6 (-0.4, 7.9) -0.5 (-8.2, 7.5)
≥15 3.4 (-0.1, 7.1) 3.4 (-1.1, 8.2) -2.6 (-11.2, 6.5)
P trendb 0.051 0.12 0.59
  1. aDifferences derived with respect to reference levels: 25% for percentage density, 30 cm2 for dense area and 110 cm2 for non-dense area. Models defined as A: analyses adjusted for age at mammogram (47–50, 50–54, 55–59 (baseline), 60–64, 65–69, 70–73 years), duration of oral contraception use (never (baseline), <5, 10–14, ≥15 years, not known), postmenopausal hormone treatment (never (baseline), former, current/<5, current/5–9, current/≥10 years duration), menopausal status and time since menopause (<5 (baseline), 10–14, 15–19, ≥20, unknown years postmenopausal, not postmenopausal), age at first birth and parity (nulliparous, 10–24 years/1–2, 10–24 years/≥3, 25–29 years/1–2 (baseline), 25–29 years/≥3, 30 years/≥1), alcohol units (none (baseline), 1–4 to ≥25, in 5-unit increments), physical activity (<31 (baseline), 32–55, 56–88, ≥88 metabolic energy equivalents/h/week); B: adjusted for covariates in model A plus body mass index (BMI) (<20.0 (baseline) to >35.0, in 2.5 kg/m2 increments); C: adjusted for covariates in model B plus weight compared with peers at age 11 years (thinner (baseline), about the same, heavier, not known). b P trend for linear regression fitted through categories of exposure
  2. The p-values in bold are those with p<0.05