TABLE 2.
Effect of CaD supplements on health outcomes grouped by personal use of calcium and/or vitamin D supplements at randomization1
| No personal calcium or vitamin D use2 | Any personal calcium or vitamin D use2 | ||||||||
| CaD group(n = 7891) | Placebo group(n = 7755) | HR (95% CI) | P3 | CaD group(n = 10,285) | Placebo group(n = 10,351) | HR (95% CI) | P3 | P-interaction4 | |
| n (events/1000 patient-years) | n (events/1000 patient-years) | n (events/1000 patient-years) | n (events/1000 patient-years) | ||||||
| Total cancer | 633 (11.6) | 715 (13.5) | 0.86 (0.78, 0.96) | 0.007 | 946 (13.7) | 890 (12.8) | 1.06 (0.97, 1.17) | 0.20 | 0.003 |
| Total breast cancer | 261 (4.7) | 310 (5.7) | 0.82 (0.70, 0.97) | 0.021 | 412 (5.9) | 381 (5.4) | 1.08 (0.94, 1.24) | 0.27 | 0.012 |
| Invasive breast cancer | 209 (3.7) | 256 (4.7) | 0.80 (0.66, 0.96) | 0.015 | 326 (4.6) | 291 (4.1) | 1.12 (0.96, 1.31) | 0.16 | 0.005 |
| In situ breast cancer | 54 (1.0) | 58 (1.1) | 0.92 (0.63, 1.33) | 0.65 | 89 (1.2) | 91 (1.3) | 0.98 (0.73, 1.31) | 0.89 | 0.80 |
| Colorectal cancer | 67 (1.2) | 82 (1.5) | 0.83 (0.60, 1.15) | 0.27 | 102 (1.4) | 80 (1.1) | 1.26 (0.94, 1.69) | 0.12 | 0.044 |
| Total fracture | 892 (16.7) | 892 (17.1) | 0.98 (0.89, 1.07) | 0.61 | 1210 (17.9) | 1266 (18.7) | 0.96 (0.89, 1.04) | 0.32 | 0.72 |
| Hip fracture | 68 (1.2) | 82 (1.5) | 0.85 (0.61, 1.17) | 0.31 | 107 (1.5) | 117 (1.6) | 0.93 (0.71, 1.21) | 0.59 | 0.65 |
| All-cause mortality | 336 (5.9) | 349 (6.3) | 0.94 (0.81, 1.10) | 0.44 | 408 (5.7) | 458 (6.4) | 0.88 (0.77, 1.01) | 0.06 | 0.44 |
CaD, calcium and vitamin D.
Personal calcium or vitamin D refers to use of nonprotocol calcium and/or vitamin D supplements at randomization.
P values obtained from Cox proportional hazards models stratified by age, randomization status in the Women's Health Initiative hormone and dietary modification trials, and relevant prevalent disease at baseline (history of breast cancer, colorectal cancer, or any cancer for breast, colorectal, and total cancer endpoints and history of fracture for hip and total fracture).
Interaction between CaD allocation and use or nonuse of personal calcium and/or vitamin D supplements at randomization for each endpoint tested in Cox proportional hazard models.