Association of early postoperative serum magnesium with acute kidney injury after cardiac surgery

Abstract

Introduction

Dysmagnesemia has been demonstrated to be involved in the pathophysiology of kidney diseases and is common in cardiac surgical patients. It remains unknown whether changes of serum magnesium after cardiac surgery affect AKI. We aimed to investigate the association of early postoperative magnesium with cardiac surgery-associated AKI in adults.

Methods

We conducted a multicenter retrospective cohort study involving patients who underwent cardiac surgery in the eICU Collaborative Research Database between 2014 and 2015. AKI within 7 days after surgery was defined using both serum creatinine and urine output criteria of Kidney Disease Improving Global Outcomes definition. Postoperative AKI was analyzed using multivariable logistic regression with early postoperative serum magnesium measured within the first 24 h after surgery as a continuous variable and categorically by quartiles.

Results

Postoperative AKI was identified in 3498 of 6124 (57.1%) patients receiving cardiac surgery. The median (25th–75th percentiles) early postoperative serum magnesium level of the study population was 2.3 (2.0–2.7) mg/dL. Higher serum magnesium level was associated with a higher risk of developing postoperative AKI (adjusted odds ratio (OR), 1.46 per 1 mg/dL increase; 95% confidence interval (CI), 1.31–1.62; p<.001). The multivariable-adjusted ORs (95% CIs) of postoperative AKI across increasing quartiles of serum magnesium were 1.00 (referent), 1.11 (0.95–1.29), 1.30 (1.12–1.52), and 1.72 (1.47–2.02) (p for trend <.001).

Conclusions

These data demonstrate a significantly higher incidence of AKI in patients with higher early postoperative serum magnesium who underwent cardiac surgery.

Keywords:

• Acute kidney injury
• cardiac surgery
• magnesium
• eICU

Author contributions

CX and JW conceptualized the study; CX, SS, and LC were responsible for data curation; CX, SS, LC, HW, and LT were responsible for investigation; CX, SS, LC, HS, YJ, and MZ were responsible for formal analysis; CX, LT, YJ, and JW were responsible for methodology; CX and JW were responsible for project administration; CX and JW were responsible for resources; CX, SS, HW, LT, and MZ were responsible for software; HW, YJ, and MZ were responsible for validation; JW was responsible for funding acquisition; MZ and JW provided supervision; CX, SS, and JW wrote the original draft; and JW reviewed and edited the manuscript. All authors read and approved the final manuscript.

Ethics statement

Not applicable. This study was an analysis of de-identified datasets from a publicly available database.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data generated or analyzed during this study are included in this article and its supplementary material files. Further enquiries can be directed to the corresponding author.

Additional information

Funding

This study was supported by Chinese Academy of Medical Sciences Central Public Welfare Scientific Research Institute Basal Research Expenses—Clinical and Translational Medicine Research Fund [2021-I2M-C&T-B-036].