Table 1.

Characteristics of cohort (based on the weighted sample) at baseline blood collection (1993-2001) in women in PLCO study by quintile of vitamin D metabolite

Characteristic25(OH)D*
1,25(OH)D
Q1Q3Q5Q1Q3Q5
No. controls200196202201202202
Mean
    25(OH)D (ng/mL)13.625.839.224.426.927.5
    1,25(OH)2D (pg/mL)36.538.439.623.736.255.1
    Age (y) at serum collection62.362.261.863.261.862.2
    BMI (at 18-20 y; kg/m2)21.421.121.021.721.320.6
    BMI (at baseline; kg/m2)28.927.325.428.127.425.8
    No. live births3.13.53.03.33.13.3
    Physical activity, vigorous (h/wk)2.22.73.12.62.82.7
    Alcohol (g/d)6.24.45.95.24.75.8
    Total calcium (g/d)1.11.51.71.51.41.4
Percentage§
    Residence at study entry
        Low sun46.139.338.742.746.145.8
        Moderate sun40.843.441.743.039.834.5
        High sun13.217.319.614.214.119.6
    Race/ethnicity (White)81.989.994.092.892.985.5
    Education (≥1 y college)52.352.656.455.860.459.5
    Ever smoker47.040.237.039.244.542.4
    Family history of breast cancer (first-degree relative/half-sister)18.118.515.616.217.212.4
    History of benign breast disease15.829.727.031.323.419.9
    Age at menarche (≤11 y)20.018.725.218.022.222.4
    Age at first childbirth (y)
        Nulliparous10.97.07.48.49.99.1
        <2567.271.365.762.368.665.1
        25-2914.616.120.519.415.421.8
        ≥306.55.66.49.56.23.6
    Age at menopause (<50 y)49.547.047.051.150.446.2
    Oral contraceptive use52.661.258.051.462.656.8
    Hormone therapy use (at baseline)63.175.978.168.769.476.9
    Season of serum collection
        Dec-Feb29.119.611.622.022.319.3
        Mar-May34.422.218.424.120.328.1
        Jun-Aug13.828.732.629.925.622.6
        Sep-Nov22.629.537.424.131.830.1
    Supplement with vitamin D use25.260.364.650.550.053.1
  • * Quintiles (<18.3, 18.3 to <23.5, 23.5 to <28.3, 28.3 to <33.7, ≥33.7 ng/mL).

  • Quintiles (<28.2, 28.2 to <33.5, 33.5 to <39, 39 to <46.3, ≥46.3 pg/mL).

  • Adjusted for total energy intake.

  • § Percentages do not always add up to 100% because of rounding or missing data.

  • Residential regions based on ranges of UV radiation levels obtained from annual R-B meters in states in which screening centers are located: low sun (R-B ≤ 105, Detroit, MI; Minneapolis, MN; Marshfield, WI), moderate sun (R-B = 113-134, Pittsburgh, PA; St. Louis, MO; Denver, CO; Washington, DC; Salt Lake City, UT), and high sun (R-B ≥ 154 Birmingham, AL; Honolulu, HI; ref. 21).

  • Includes multivitamin supplements, vitamin D supplements, or cod liver oil; missing are treated as not taking supplements.