Table 2.

RRs and 95% CI by quintile of serum 25(OH)D and 1,25(OH)2D

CasesEntire follow-up period
Excluding first 2 y of follow-up
Simple RR* (95% CI)Multivariate RR (95% CI)Multivariate RR (95% CI)
25(OH)D
Quintile
    11721.01.01.0
    21881.09 (0.82-1.45)1.02 (0.75-1.41)1.04 (0.74-1.48)
    32441.43 (1.08-1.89)1.36 (0.99-1.87)1.25 (0.88-1.77)
    42051.20 (0.90-1.60)1.13 (0.82-1.55)1.12 (0.78-1.59)
    51961.15 (0.86-1.53)1.04 (0.75-1.45)1.04 (0.72-1.51)
Ptrend§0.330.810.82
1,25(OH)2D
Quintile
    11661.01.01.0
    21861.22 (0.91-1.63)1.22 (0.90-1.66)1.19 (0.85-1.68)
    32061.25 (0.94-1.66)1.28 (0.94-1.73)1.31 (0.94-1.83)
    42341.46 (1.10-1.93)1.47 (1.09-1.98)1.45 (1.04-2.01)
    52121.32 (0.99-1.75)1.23 (0.91-1.68)1.27 (0.90-1.78)
Ptrend§0.040.140.14
  • * Adjusted for study design matching factor [period of blood draw (before September 30, 1997, September 30, 1997 or after) and age (as the timeline)] and season of serum collection (December-February, March-May, June-July, August-September).

  • Additionally adjusted for BMI (ages 18-20), age at menarche, age at menopause, hormone replacement therapy use, benign breast disease, family history of breast cancer, combination of parity and age at first birth, smoking status, daily alcohol intake, and daily dietary calcium intake.

  • <18.3, 18.3 to <23.5, 23.5 to <28.3, 28.3 to <33.7, and ≥33.7 ng/mL.

  • § Calculated based on assigning a median value to each category of measured values and modeling the resulting variable as continuous.

  • <28.2, 28.2 to <33.5, 33.5 to <39, 39 to <46.3, and ≥46.3 pg/mL.