Table 2.

Description of the intervention among the 391 participants by study arm

Vitamin D3
Description of interventionPlacebo (n = 96)1,000 IU/day (n = 96)2,000 IU/day (n = 99)3,000 IU/day (n = 100)
Interval between mammogramsa (days) (mean ± SD)376 ± 12374 ± 12374 ± 10374 ± 11
Concordant typesb of mammogramsa (%)99.0100.097.097.0
Actual duration of interventionc (days) (mean ± SD)351 ± 19346 ± 20348 ± 17350 ± 17
Adherence to interventiond (%)90.692.796.092.0
Serum 25(OH)D3e (nmol/L) (mean ± SD)62.9 ± 20.592.2 ± 28.1109.7 ± 26.6128.9 ± 37.4
  • aThe first mammogram at baseline and the second mammogram at the end of the one-year intervention.

  • bDigital direct radiography or digital computed radiography.

  • cFrom the first Monday after randomization until the day of the mammography at the end of intervention. The actual duration of the intervention ranged between 301 and 406 days.

  • dUse of ≥80% of doses during both first and last 6 months of intervention (%).

  • eSerum 25(OH)D3 assessed at the end of the one-year intervention.