Table 2.
Age adjusted and multivariable relative risks for incident primary hyperparathyroidism according to dietary and total calcium intake*
| Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | P for trend | |
|---|---|---|---|---|---|---|
| Dietary calcium intake | ||||||
| Median within group (mg/day) | 443 | 564 | 670 | 806 | 1070 | — |
| No of cases of primary hyperparathyroidism | 69 | 57 | 57 | 50 | 44 | — |
| No of person years | 290 985 | 296 872 | 298 068 | 297 109 | 292 944 | — |
| Age adjusted relative risk (95% CI) | 1.0 | 0.81 (0.57 to 1.15) | 0.80 (0.56 to 1.14) | 0.70 (0.49 to 1.01) | 0.61 (0.42 to 0.90) | 0.03 |
| Multivariable relative risk (95% CI)† | 1.0 | 0.79 (0.55 to 1.13) | 0.78 (0.54 to 1.11) | 0.66 (0.45 to 0.98) | 0.56 (0.37 to 0.86) | 0.009 |
| Total calcium intake | ||||||
| Median within group (mg/day) | 522 | 737 | 999 | 1276 | 1794 | — |
| No of cases of primary hyperparathyroidism | 86 | 61 | 43 | 42 | 45 | — |
| No of person years | 289 554 | 294 850 | 297 322 | 298 933 | 295 321 | — |
| Age adjusted relative risk (95% CI) | 1.0 | 0.69 (0.50 to 0.96) | 0.48 (0.33 to 0.69) | 0.45 (0.31 to 0.65) | 0.48 (0.33 to 0.69) | <0.001 |
| Multivariable relative risk (95% CI)‡ | 1.0 | 0.64 (0.46 to 0.91) | 0.42 (0.28 to 0.62) | 0.39 (0.25 to 0.58) | 0.41 (0.27 to 0.63) | <0.001 |
Population divided into five equal groups according to intake of calcium.
*For illustrative purposes, medians within each group for intake of dietary and total calcium were derived from responses to the 1986 dietary questionnaire. However, the period specific medians were used for the 1986-2008 analysis. Relative risks are for the risk of primary hyperparathyroidism compared with the group that had the lowest intake of dietary or total calcium (that is, group 1).
†Multivariable model includes age, body mass index (categories: <22, 22-24.9, 25-29.9, ≥30), race, smoking status (past, current, or never), calcium supplement intake, total vitamin D intake, dietary intakes of vitamin A and protein, alcohol intake, and diuretic use (thiazide or loop diuretic use).
‡Multivariable model includes age, body mass index (categories: <22, 22-24.9, 25-29.9, ≥30), race, smoking status (past, current, or never), total vitamin D intake, dietary intakes of vitamin A and protein, alcohol intake (categories: none, 0.1-4.9, 5-14.9, ≥15 g/day), and diuretic use (thiazide or loop diuretic use).