Impact of Calcium Phosphate Product on Acute Kidney Injury and Mortality: A Retrospective Cohort Study.

Abstract

This study aims to assess the association between admission-corrected serum calcium phosphate (CaPO4) levels and the risks of in-hospital acute kidney injury (AKI) and mortality, hypothesizing a dose-dependent relationship between serum CaPO4 concentrations and the likelihood of developing AKI. This large retrospective cohort study analyzed hospitalized adult patients who had serum calcium, phosphate, and albumin levels measured within 24 hours of admission between January 2014 and December 2018. Piecewise regression was employed to identify the optimal CaPO4 cutoff values for predicting in-hospital AKI and mortality. Subsequently, the odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the risks of in-hospital AKI and mortality associated with these cutoff values. A total of 2,116 patients were included in the study. The incidence rates of AKI for patients with CaPO4 levels ≤27 and >27 mg2/dL2 were 9.6% and 10.9%, respectively. The bilinear association pattern revealed the lowest risk of AKI at a CaPO4 level of 27 mg2/dL2. Piecewise regression analysis showed that each 1 mg2/dL2 increase in CaPO4 level above the 27 mg2/dL2 cutoff was associated with increased risks of in-hospital AKI and mortality, with OR of 1.048 (95% CI: 1.030-1.065) and 1.048 (95% CI: 1.032-1.065), respectively. Our findings indicate a critical relationship between elevated serum CaPO4 levels and increased risks of in-hospital AKI and mortality, with a notable cutoff at CaPO4 >27 mg2/dL2.