Conjoint Effects of Serum Calcium and Phosphate on Risk of Total, Cardiovascular, and Noncardiovascular Mortality in the Community
Objective— Hyperphosphatemia is a cardiovascular risk factor in patients with chronic kidney disease. Relations of circulating calcium (Ca) and phosphorus (Pi) to long-term mortality risk in the community require further investigation.
Methods and Results— Associations of serum Ca and Pi to mortality were evaluated in a community-based cohort of 2176 men (mean age, 50.1 years). During follow-up (median, 29.8 years), 1009 men died, and 466 of these deaths resulted from cardiovascular causes. In Cox proportional hazards models, serum Pi and [Ca×Pi] were independent predictors of total mortality (hazard ratio per SD, 1.06; 95% CI, 1.01–1.12; P=0.03; 1.07; 95% CI, 1.01–1.12; P=0.01) and cardiovascular mortality (1.10; 95% CI, 1.02–1.18; P=0.01; 1.10; 95% CI, 1.03–1.19; P=0.008). Serum Ca was associated with risk of total mortality (1.08; 95% CI, 1.01–1.16; P=0.02) and noncardiovascular mortality (1.10; 95% CI, 1.01–1.21; P=0.04). Results were consistent after multivariate adjustments in subsamples of individuals with estimated glomerular filtration rate >90 mL/min and low-to-normal serum Ca and Pi.
Conclusion— Circulating Ca and Pi levels are associated with risks of total, cardiovascular, and noncardiovascular mortality in the community, and their conjoint effects are additive. Additional studies are warranted to evaluate whether Ca and Pi are modifiable risk factors in the general population.