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U-shaped association between serum calcium and in-hospital mortality in patients with congestive heart failure
Kai Zhang1, Yu Han2, Tianyi Cai3
1Department of Cardiovascular Surgery, The Second Hospital of Jilin University, Changchun, Jilin, China.
Insights
Serum calcium levels show a U-shaped association with in-hospital mortality in congestive heart failure (CHF) patients. Both low and high calcium levels increase mortality risk, with the lowest risk observed at 8.35 mg/dL.
Area of Science:
- Cardiology
- Clinical Biochemistry
Background:
- Serum calcium is a common biomarker for disease severity.
- Its precise impact on clinical outcomes in congestive heart failure (CHF) patients is not well understood.
Purpose of the Study:
- To investigate the relationship between serum calcium levels and in-hospital mortality in CHF patients.
Main Methods:
- Retrospective analysis of 15,983 CHF patients from the MIMIC database.
- Stratification of patients by serum calcium levels (quintiles).
- Statistical analysis including multivariable logistic regression, generalized additive models, and two-piecewise linear regression.
Main Results:
- A U-shaped relationship was observed between serum calcium levels and in-hospital mortality.
- Both the lowest (Q1) and highest (Q5) calcium levels were associated with increased mortality risk (OR 1.38 and 1.23, respectively).
- The lowest risk of mortality occurred at a serum calcium threshold of 8.35 mg/dL.
Conclusions:
- Serum calcium levels exhibit a U-shaped association with in-hospital mortality in CHF patients, with an inflection point at 8.35 mg/dL.
- Further prospective studies are needed to confirm these findings.
Aims:
Serum calcium level is widely used for evaluating disease severity, but its impact on clinical outcomes in patients with congestive heart failure (CHF) remains poorly understood. The aim of this study is to investigate the relationship between serum calcium levels and in-hospital mortality in CHF patients.
Methods And Results:
We conducted a retrospective analysis utilizing clinical data from the Medical Information Mart for Intensive Care database, encompassing a cohort of 15 983 CHF patients. This cohort was stratified based on their serum calcium levels, with the primary objective being the determination of in-hospital mortality. To assess the impact of admission serum calcium levels on in-hospital mortality, we employed various statistical methodologies, including multivariable logistic regression models, a generalized additive model, a two-piecewise linear regression model, and subgroup analysis. Comparative analysis of the reference group (Q3) revealed increased in-hospital mortality in the first quintile (Q1, the group with the lowest blood calcium level) and the fifth quintile (Q5, the group with the highest blood calcium level), with fully adjusted odds ratios of 1.38 [95% confidence interval (CI): 1.13-1.68, P = 0.002] and 1.23 (95% CI: 1.01-1.5, P = 0.038), respectively. A U-shaped relationship was observed between serum calcium levels and in-hospital mortality, with the lowest risk occurring at a threshold of 8.35 mg/dL. The effect sizes and corresponding CIs below and above this threshold were 0.782 (95% CI: 0.667-0.915, P = 0.0023) and 1.147 (95% CI: 1.034-1.273, P = 0.0094), respectively. Stratified analyses confirmed the robustness of this correlation.
Conclusions:
Our study identifies a U-shaped association between serum calcium levels and in-hospital mortality in CHF patients, with a notable inflection point at 8.35 mg/dL. Further investigation through prospective, randomized, and controlled studies is warranted to validate the findings presented in this study.
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