Admission serum phosphate levels predict hospital mortality

ABSTRACT

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.

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 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 <2.5, 4.3–4.8 and ≥4.9 mg/dL, respectively. Among subgroups of patients with chronic kidney disease (CKD) and cardiovascular disease (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 CKD patients and 5.11 (95%CI 3.33–7.95) in CVD patients.

Conclusion: Hospitalized patients with admission serum phosphate <2.5 and >4.2 mg/dL are associated with an increased risk of in-hospital mortality. The highest mortality risk is associated with CKD and CVD patients with admission hyperphosphatemia.

KEYWORDS:

• Phosphate
• hypophosphatemia
• hyperphosphatemia
• mortality
• chronic kidney disease
• cardiovascular disease

Acknowledgments

None reported.

Declaration of interest

The authors have disclosed that they have no significant relationships with or financial interests in any commercial companies related to this study or article. Hospital Practice peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Supplementary Material

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Additional information

Funding

This manuscript was not funded.

Notes on contributors

Wisit Cheungpasitporn

All authors had access to the data and a role in writing the manuscript.