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Admission serum phosphate levels predict hospital mortality
Wisit Cheungpasitporn1,2, Charat Thongprayoon1,3, Michael A Mao1
1a Division of Nephrology and Hypertension, Department of Medicine , Mayo Clinic , Rochester , MN , USA.
Insights
Hospitalized patients with low or high serum phosphate levels face increased in-hospital mortality risk. This risk is highest for patients with chronic kidney disease or cardiovascular disease and elevated phosphate levels.
Area of Science:
- Clinical Chemistry
- Nephrology
- Cardiology
Background:
- Admission serum phosphate levels are a potential predictor of patient outcomes.
- Understanding these associations is crucial for optimizing patient care and management.
Purpose of the Study:
- To investigate the relationship between admission serum phosphate levels and in-hospital mortality.
- To identify specific phosphate level thresholds associated with increased mortality risk.
Main Methods:
- Analysis of data from 42,336 adult hospitalized patients between 2009 and 2013.
- Categorization of admission serum phosphate into six groups (mg/dL).
- Logistic regression analysis to determine odds ratios (OR) for in-hospital mortality.
Main Results:
- A U-shaped association was observed between serum phosphate levels and in-hospital mortality.
- Levels below 3.1 mg/dL and above 4.2 mg/dL were linked to higher mortality.
- Significantly elevated mortality risks (ORs ranging from 1.60 to 3.89) were found for phosphate levels <2.5 mg/dL and >4.2 mg/dL.
Conclusions:
- Admission serum phosphate levels outside the 3.1-4.2 mg/dL range are associated with increased in-hospital mortality.
- Patients with chronic kidney disease (CKD) and cardiovascular disease (CVD) exhibit the highest mortality risk with hyperphosphatemia (≥4.9 mg/dL).
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.
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