Iron metabolism-related indicators as predictors of the incidence of acute kidney injury after cardiac surgery: a meta-analysis

Abstract

Background

Some studies have found that ferroptosis plays an important role in the incidence of acute kidney injury (AKI) after cardiac surgery. However, whether iron metabolism-related indicators can be used as predictors of the incidence of AKI after cardiac surgery remains unclear.

Objectives

We aimed to systematically evaluate whether iron metabolism-related indicators can be used as predictors of the incidence of AKI after cardiac surgery via meta-analysis.

Search methods: The PubMed, Embase, Web of Science, and Cochrane Library databases were searched from January 1971 to February 2023 to identify prospective observational and retrospective observational studies examining iron metabolism-related indicators and the incidence of AKI after cardiac surgery among adults.

Data Extraction and Synthesis: The following data were extracted by two independent authors (ZLM and YXY): date of publication, first author, country, age, sex, number of included patients, iron metabolism-related indicators, outcomes of patients, patient types, study types, sample, and specimen sampling time. The level of agreement between authors was determined using Cohen’s κ value. The Newcastle–Ottawa Scale (NOS) was used to evaluate the quality of studies. Statistical heterogeneity across the studies was measured by the I² statistic. The standardized mean difference (SMD) and 95% confidence interval (CI) were used as effect size measures. Meta-analysis was performed using Stata 15.

Results

After applying the inclusion and exclusion criteria, 9 articles on iron metabolism-related indicators and the incidence of AKI after cardiac surgery were included in this study. Meta-analysis revealed that after cardiac surgery, baseline serum ferritin (μg/L) (I² = 43%, fixed effects model, SMD = −0.3, 95% CI:-0.54 to −0.07, p = 0.010), preoperative and 6-hour postoperative fractional excretion (FE) of hepcidin (%) (I² = 0.0%, fixed effects model, SMD = −0.41, 95% CI: −0.79 to −0.02, p = 0.038; I² = 27.0%, fixed effects model, SMD = −0.49, 95% CI: −0.88 to −0.11, p = 0.012), 24-hour postoperative urinary hepcidin (μg/L) (I² = 0.0%, fixed effects model, SMD = −0.60, 95% CI: −0.82 to −0.37, p < 0.001) and urine hepcidin/urine creatinine ratio (μg/mmoL) (I² = 0.0%, fixed effects model, SMD = −0.65, 95% CI: −0.86 to −0.43, p < 0.001) were significantly lower in patients who developed to AKI than in those who did not.

Conclusion

After cardiac surgery, patients with lower baseline serum ferritin levels (μg/L), lower preoperative and 6-hour postoperative FE of hepcidin (%), lower 24-hour postoperative hepcidin/urine creatinine ratios (μg/mmol) and lower 24-hour postoperative urinary hepcidin levels (μg/L) are more likely to develop AKI. Therefore, these parameters have the potential to be predictors for AKI after cardiac surgery in the future. In addition, there is a need for relevant clinical research of larger scale and with multiple centers to further test these parameters and prove our conclusion.

Trial Registration: PROSPERO identifier: CRD42022369380.

Keywords:

• Iron metabolism
• incidence
• acute kidney injury
• cardiac surgery
• meta-analysis

Author contributions

Xiaoshuang Zhou designed and outlined the work; Shengchao Zhang revised the whole paper; Limei Zhao, Xiaoyu Yang and Xiaoshuang Zhou selected studies, evaluated the quality of the included studies, and drafted and revised the manuscript. All authors approved the article’s final version and agreed to be accountable for all aspects of the work.

Disclosure statement

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

Data availability statement

All data analyzed during this study are available in the public domain.

Additional information

Funding

This work was supported by grants from the National Natural Science Foundation of China (NSFC) (Grant Numbers 82170708), Key Research and Development (R&D) Projects of Shanxi Province (201803D31151) and Scientific Research Project Funded by International Students of Shanxi Province (2020-182).