Abstract: TH-PO1049

Impact of Admission Serum Phosphate Levels on Mortality in Hospitalized Patients

Session Information

Category: Mineral Disease

  • 1201 Mineral Disease: Ca/Mg/PO4

Authors

  • Mao, Michael A., Mayo Clinic, Rochester, Minnesota, United States
  • Cheungpasitporn, Wisit, Mayo Clinic, Rochester, Minnesota, United States
  • Thongprayoon, Charat, Bassett Medical Center, Cooperstown, New York, United States
  • Kittanamongkolchai, Wonngarm, Mayo Clinic, Rochester, Minnesota, United States
  • Sakhuja, Ankit, Mayo Clinic, Rochester, Minnesota, United States
  • Erickson, Stephen B., Mayo Clinic, Rochester, Minnesota, United States
Background

The aim of this study was to assess the relationship between admission serum phosphate levels and in-hospital mortality in all hospitalized patients.

Methods

All adult hospitalized patients who had admission serum phosphate available between years 2009 and 2013 were enrolled. Admission serum phosphate was categorized based on its distribution into six groups (<2.5, 2.5-3.0, 3.1-3.6, 3.7-4.2, 4.3-4.8 and ≥4.9 mg/dL). The odds ratio (OR) of in-hospital mortality by admission serum phosphate, using the phosphate category of 3.1-3.6 mg/dL as the reference group, was obtained by logistic regression analysis. Pre-specified subgroup analysis stratified by chronic kidney disease (CKD) and cardiovascular disease (CVD) status was performed.

Results

42,336 patients were studied. The lowest incidence of in-hospital mortality was associated with a serum phosphate within 3.1-4.2 mg/dL. A U-shaped curve emerged demonstrating higher in-hospital mortality associated with both serum phosphate <3.1 and >4.2 mg/dL. After adjusting for potential confounders, both serum phosphate <2.5 and >4.2 mg/dL were associated with an increased risk of in-hospital mortality with ORs of 1.60 (95% CI 1.25-2.05), 1.60 (95% CI 1.29-1.97) and 3.89 (95% CI 3.20-4.74) when serum phosphate were within <2.5, 4.3-4.8 and ≥4.9 mg/dL, respectively. Among subgroups of patients with CKD and CVD, the highest mortality was associated with a serum phosphate ≥4.9 mg/dL with ORs of 4.11 (95% CI 3.16-5.39) in patients with CKD and 5.11 (95% CI 3.33-7.95) in patients with CVD. While serum phosphate <2.5 mg/dL was associated with increased in-hospital mortality in patients with CVD (OR 3.24, 95% CI 1.82-5.58), the risk was not significantly increased among CKD patients with serum phosphate <2.5 mg/dL.

Conclusion

Hospitalized patients with admission serum phosphate <2.5 and >4.2 mg/dL are associated with an increased risk of in-hospital mortality. In addition, CKD and CVD patients with hyperphosphatemia at admission (≥4.9 mg/dL) carry the highest mortality risk.