Impact of Admission Calcium-phosphate Product on 1-year Mortality among Hospitalized Patients

BACKGROUND: Calcium-phosphate product is associated with mortality among patients with end-stage kidney disease on dialysis. However, clinical evidence among hospitalized patients is limited. The objective of this study was to investigate the relationship between admission calcium-phosphate product and 1-year mortality in hospitalized patients. MATERIALS AND METHODS: All adult patients admitted to a tertiary referral hospital in 2009–2013 were studied. Patients who had both available serum calcium and phosphate measurement within 24 h of hospital admission were included. Admission calcium-phosphate product (calcium × phosphate) was stratified based on its distribution into six groups: <21, 21–<27, 27–<33, 33–<39, 39–<45, and ≥45 mg(2)/dL(2). Multivariate cox proportional hazard analysis was performed to evaluate the association between admission calcium-phosphate product and 1-year mortality, using the calcium-phosphate product of 33–<39 mg(2)/dL(2) as the reference group. RESULTS: A total of 14,772 patients were included in this study. The mean admission calcium-phosphate product was 34.4 ± 11.3 mg(2)/dL(2). Of these patients, 3194 (22%) died within 1 year of hospital admission. In adjusted analysis, admission calcium-phosphate product of ≥45 mg(2)/dL(2) was significantly associated with increased 1-year mortality with hazard ratio of 1.41 (95% 95% confidence interval 1.25–1.67), whereas lower admission calcium-phosphate product was not significantly associated with 1-year mortality. CONCLUSION: Elevated calcium-phosphate product was significantly associated with increased 1-year mortality in hospitalized patients.