Serum calcium, phosphorus and cardiovascular events in post-menopausal women

Background: There is increasing evidence linking phosphorus and calcium levels to a higher risk of cardiovascular morbidity and mortality in the general population. Methods: We performed a post hoc data analysis from the Multiple Outcomes of Raloxifene Evaluation (MORE) trial of raloxifene treatment in 7259 postmenopausal women with osteoporosis to test the hypothesis that higher baseline calcium and phosphorus levels are associated with a higher risk of incident cardiovascular events during 4 years of follow-up. Results: Baseline mean (SD) values were 2.3 (0.1) mmol/L for serum calcium, 1.2 (0.2) mmol/L for serum phosphorus. Adjusted for multiple covariates including 25(OH)D, parathyroid hormone, and phosphorus, adjusted hazard ratios (AHR) (95% confidence interval (CI)) per SD of calcium were: 1.17(1.01-1.35), p = 0.03 for combined cardiovascular outcome, 1.22(0.99-1.49), p = 0.06 for cerebrovascular events, 1.12(0.92-1.37), p = 0.25 for coronary heart disease, and 1.18(0.94-1.48), p = 0.16 for death. While there was some evidence that higher serum phosphorus levels were associated with higher rate of combined cardiovascular outcome (p = 0.07) and cerebrovascular events (p = 0.03) in pauci-variable analysis, these associations did not persist after adjustment for additional confounders. Adjusted for multiple covariates including 25(OH)D, parathyroid hormone, and calcium, AHR(95% CI) per SD of phosphorus were 0.88(0.77-1.01), p = 0.07 for combined cardiovascular outcome, 0.86(0.70-1.06), p = 0.15 for ceverbrovascular events, 0.92(0.76-1.10), p = 0.35 for coronary heart disease, and 1.00(0.80-1.25) for death. Conclusion: We found an independent association between higher baseline serum calcium levels and higher rate of cardiovascular events. Our findings did not support an independent association between serum phosphorus levels and cardiovascular events.