Table 3.
Intakes of calcium and sources of calcium during adolescence and relative risk (95% confidence interval) of proliferative BBD in NHSII
| Exposures | Quintile of calcium intake
|
P trend | ||||
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | ||
| Calcium | ||||||
| Intake (mg/day)* | 675 | 863 | 1038 | 1251 | 1542 | |
| No. of BBD cases§/pys¶ | 138/51,869 | 148/51,790 | 127/51,996 | 133/51,903 | 136/52,270 | |
| Multivariate RR (95% CI)† | 1.00 (ref) | 1.12 (0.89, 1.42) | 0.97 (0.76, 1.24) | 1.00 (0.78, 1.27) | 1.04 (0.82, 1.32) | 0.91 |
| Additional adjustment for vitamin D† | 1.00 (ref) | 1.17 (0.91, 1.50) | 1.06 (0.81, 1.40) | 1.14 (0.85, 1.54) | 1.25 (0.91, 1.72) | 0.24 |
|
| ||||||
| Dairy calcium | ||||||
| Intake (mg/day)* | 350 | 544 | 729 | 957 | 1275 | |
| No. of BBD cases§/pys¶ | 130/52,066 | 145/51,801 | 133/51,926 | 133/51,939 | 141/52,096 | |
| Multivariate RR (95% CI)† | 1.00 (ref) | 1.15 (0.91, 1.46) | 1.05 (0.82, 1.34) | 1.03 (0.81, 1.32) | 1.11 (0.87, 1.42) | 0.71 |
| Additional adjustment for non-dairy calcium† | 1.00 (ref) | 1.15 (0.90, 1.46) | 1.04 (0.81, 1.33) | 1.02 (0.79, 1.31) | 1.08 (0.84, 1.39) | 0.90 |
|
| ||||||
| Non-dairy calcium | ||||||
| Intake (mg/day)* | 229 | 267 | 297 | 330 | 386 | |
| No. of BBD cases§/pys¶ | 163/51,562 | 127/51,800 | 143/51,759 | 131/51,839 | 118/52,869 | |
| Multivariate RR (95% CI)† | 1.00 (ref) | 0.80 (0.63, 1.01) | 0.96 (0.76, 1.20) | 0.91 (0.72, 1.15) | 0.86 (0.67, 1.11) | 0.47 |
| Additional adjustment for dairy calcium† | 1.00 (ref) | 0.80 (0.63, 1.01) | 0.96 (0.76, 1.21) | 0.91 (0.71, 1.16) | 0.86 (0.66, 1.12) | 0.51 |
*
Values for calcium, dairy calcium, and dairy protein are medians of nutrient intakes in each quintile, adjusted for total energy intake using the residual method. Values for non-dairy calcium are medians of raw nutrient values in each quintile.
§
682 cases of proliferative BBD (with or without atypia) were diagnosed during the follow-up period 1991–2001.
†
The multivariate models are adjusted the same way as in Table 2. The age-adjusted results are essentially the same, and only multivariate adjusted results are presented. Models with calcium as the exposure variable are not adjusted for multivitamin use.