The relationship between serum anion gap levels and short-, medium-, and long-term all-cause mortality in ICU patients with congestive heart failure: a retrospective cohort study

Abstract

Background

There hasn’t been research done on the connection between serum anion gap (AG) levels and long-, medium-, and short-term all-cause mortality in congestive heart failure (CHF) patients. This study aims to investigate the association between serum anion gap levels and all-cause mortality in CHF patients after adjusting for other covariates.

Methods

For each patient, we gather demographic information, comorbidities, laboratory results, vital signs, and scoring data using the ICU (Intensive Care Unit) Admission Scoring System from the MIMIC-III database. The connection between baseline AG and long-, medium-, and short-term all-cause mortality in critically ill congestive heart failure patients was investigated using Kaplan-Meier survival curves, subgroup analysis, restricted cubic spline, and Cox proportional risk analysis.

Results

4840 patients with congestive heart failure in total were included in this study. With a mean age of 72.5 years, these patients had a gender split of 2567 males and 2273 females. After adjusting for other covariates, a multiple regression analysis revealed that, in critically ill patients with congestive heart failure, all-cause mortality increased significantly with rising AG levels. In the fully adjusted model, we discovered that AG levels were strongly correlated with 4-year, 365-day, 90-day, and 30-day all-cause mortality in congestive heart failure patients with HRs (95% CI) of 1.06 (1.04, 1.08); 1.08 (1.05, 1.10); and 1.08 (1.05, 1.11) (p-value < 0.05). Our subgroup analysis’s findings demonstrated a high level of consistency and reliability. K-M survival curves demonstrate that high serum AG levels are associated with a lower survival probability.

Conclusion

Our research showed the association between CHF patients’ all-cause mortality and anion gap levels was non-linear. Elevated anion gap levels are associated with an increased risk of long-, medium-, and short-term all-cause death in patients with congestive heart failure. Continuous monitoring of changes in AG levels may have a clinical predictive role.

Graphical Abstract

Keywords:

• All-cause mortality
• congestive heart failure
• cox proportional hazards regression
• K-M survival curves
• serum anion gap

Acknowledgments

We thank Ms. Linlin Jiang and Ms. Xinglin Chen who offered instruction in the data analysis process.

Ethical approval

The research carried out is not related to human or animal use.

Consent to participation and ethical approval

The Massachusetts Institute of Technology (Cambridge, MA) and Beth Israel Deaconess Medical Centre (Boston, MA) approved the database’s establishment, and consent was acquired for the first data gathering. Hence, this research was exempt from the ethical approval statement and the necessity of informed consent.

Authorisation to publish

Not applicable.

Authors’ contributions

Shixuan Peng and Qisheng Chen was in charge of the research’s overall execution and manuscript writing, while Weiqi Ke and Yongjun Wu were in charge of analysing the data.

Disclosure statement

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

Data and materials accessibility

The datasets used in this investigation may be found in the MIMIC-III database (https://archive.physionet.org/works/MIMICIIIClinicalDatabase/files/). The database used in the study is publicly available.

Additional information

Funding

This work was supported by Hunan Provincial Demonstration Base of Clinical Medical Technology for Pathological Diagnosis (No. 2019SK4026), Research on the Development and Application of Titrated Single-molecule Digital PCR System (2021SK52301) and Major Research Programs for High-level Talents in Healthcare in Hunan Province (R2023184).