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Multicenter Study
. 2025 Jan 1;111(1):761-770.
doi: 10.1097/JS9.0000000000001861.

Association between frailty and acute kidney injury after cardiac surgery: unraveling the moderation effect of body fat through an international, retrospective, multicohort study

Yun-Xiao Bai  1   2   3 , Zi-Hao Wang  4 , Yong Lv  1   2   3 , Jie Liu  1   2   3 , Zhen-Zhen Xu  1   2   3 , Yi-Qi Feng  1   2   3 , Guo-Yang Liu  1   2   3 , Ping Yin  5 , Yan-Ting Wang  1   2   3 , Nian-Guo Dong  4 , Qing-Ping Wu  1   2   3
Affiliations
Multicenter Study

Association between frailty and acute kidney injury after cardiac surgery: unraveling the moderation effect of body fat through an international, retrospective, multicohort study

Yun-Xiao Bai et al. Int J Surg. .

Abstract

Background: Acute kidney injury (AKI) is a common and serious complication after cardiac surgery that significantly affects patient outcomes. Given the limited treatment options available, identifying modifiable risk factors is critical. Frailty and obesity, two heterogeneous physiological states, have significant implications for identifying and preventing AKI. Our study investigated the interplay among frailty, body composition, and AKI risk after cardiac surgery to inform patient management strategies.

Material and methods: This retrospective cohort study included three international cohorts. Primary analysis was conducted on adult patients who underwent cardiac surgery between 2014 and 2019 at Wuhan Union Hospital, China. We tested the generalizability of our findings with data from two independent international cohorts, the Medical Information Mart for Intensive Care IV (MIMIC-IV) and the eICU Collaborative Research Database. Frailty was assessed using a clinical lab-based frailty index (FI-LAB), while total body fat percentage (BF%) was calculated based on a formula accounting for BMI, sex, and age. Logistic regression models were used to analyze the associations between frailty, body fat, and AKI, adjusting for pertinent covariates.

Results: A total of 8785 patients across three international cohorts were included in the study. In the primary analysis of 3569 patients from Wuhan Union Hospital, moderate and severe frailty were associated with an increased AKI risk after cardiac surgery. Moreover, a nonlinear relationship was observed between BF% and AKI risk. When stratified by the degree of frailty, lower body fat correlated with a decreased incidence of AKI. Extended analyses using the MIMIC-IV and eICU cohorts ( n =3951 and n =1265, respectively) validated these findings and demonstrated that a lower total BF% was associated with decreased AKI incidence. Moderation analysis revealed that the effect of frailty on AKI risk was moderated by the BF%. Sensitivity analyses demonstrated results consistent with the main analyses.

Conclusion: Higher degrees of frailty were associated with an elevated risk of AKI following cardiac surgery, and total BF% moderated this relationship. This research underscores the significance of integrating frailty and body fat assessments into routine cardiovascular care to identify high-risk patients for AKI and implement personalized interventions to improve patient outcomes.

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Conflict of interest statement

The author(s) have no potential conflicts of interest to disclose.

Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.

Figures

Figure 1
Figure 1
Flow diagram of the selection process of the eligible population. AKI, acute kidney injury; CABG, coronary artery bypass grafting; eICU, eICU Collaborative Research Database; MIMIC-III, Medical Information Mart for Intensive Care III.
Figure 2
Figure 2
Association between frailty, body fat percentage, and AKI. (A) Association between different frailty status and AKI. (B) The LOWESS curve indicated a nonlinear association between total BF% and AKI. (C) The restricted cubic spline indicated a nonlinear association between total BF% and AKI. AKI, acute kidney injury; BF%, body fat percentage; OR, odds ratio.
Figure 3
Figure 3
Association between body fat percentage and AKI when stratified by degrees of frailty in Wuhan Union Cohort. AKI, acute kidney injury; BF%, body fat percentage; OR, odds ratio;.
Figure 4
Figure 4
Association between body fat percentage and AKI when stratified by degrees of frailty in MIMIC- IV and eICU Cohort. AKI, acute kidney injury; BF%, body fat percentage; OR, odds ratio.
Figure 5
Figure 5
Moderation effect of total body fat percentage, represented as five quintiles, on the association between frailty index score and the risk of AKI. AKI, acute kidney injury; FI, frailty index.
See this image and copyright information in PMC

References

    1. Wang Y, Bellomo R. Cardiac surgery-associated acute kidney injury: risk factors, pathophysiology and treatment. Nat Rev Nephrol 2017;13:697–711. - PubMed
    1. Wang C, Gao Y, Tian Y, et al. . Prediction of acute kidney injury after cardiac surgery from preoperative N-terminal pro-B-type natriuretic peptide. Br J Anaesth 2021;127:862–870. - PubMed
    1. Bernardi MH, Schmidlin D, Ristl R, et al. . Serum creatinine back-estimation in cardiac surgery patients: misclassification of AKI using existing formulae and a data-driven model. Clin J Am Soc Nephrol 2016;11:395–404. - PMC - PubMed
    1. Mao H, Katz N, Ariyanon W, et al. . Cardiac surgery-associated acute kidney injury. Cardiorenal Med 2013;3:178–199. - PMC - PubMed
    1. Hobson CE, Yavas S, Segal MS, et al. . Acute kidney injury is associated with increased long-term mortality after cardiothoracic surgery. Circulation 2009;119:2444–2453. - PubMed

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