Association Between Serum Calcium and Acute Kidney Injury in Patients with Heart Failure:A Cohort Analysis Based on the MIMIC Database
WANG Xiao
QIAO Hui
HU Yanting
BI Jinxiao
AN Yifan
Abstract：Objective To investigate the association between serum calcium levels at ICU admission and the occurrence of acute kidney injury(AKI)in patients with heart failure(HF).Methods This retrospective study included 5 112 HF patients from the Medical Information Mart for Intensive Care(MIMIC)-Ⅲ(2001-2012)and MIMIC-Ⅳ(2008-2019)databases who were admitted to the ICU for the first time,had a hospital stay of≥2 days,and were not diagnosed with AKI within 24 hours of admission.Based on the first serum calcium level measured within 24 hours of ICU admission,patients were categorized using three methods:(1)Quartile groups:≤7.20 mg/dL,(7.21,8.20)mg/dL,(8.21,8.80)mg/dL,and>8.80 mg/dL;(2)Clinical significance groups:hypocalcemia group(≤8.40 mg/dL),normal group(8.50-10.50 mg/dL),hypercalcemia group(>10.50 mg/dL);(3)K-means clustering groups:K-means cluster analysis was performed using the cluster package in R software,and patients were divided into C1(≤7.30 mg/dL),C2(7.30-8.70 mg/dL),and C3(>8.70 mg/dL)groups based on the distribution characteristics of serum calcium data.The primary outcome was the occurrence of AKI.Univariate and multivariate logistic regression analyses were used to assess the strength of association.Restricted cubic spline(RCS)curves were employed to analyze nonlinear relationships.Receiver operating characteristic(ROC)curves were used to evaluate predictive performance.Subgroup analyses were conducted based on age(≥65 years and<65 years)and Charlson Comorbidity Index(CCI≥5 and<5).Results During the follow-up period,2,424 patients(47.42%)developed AKI.After multivariate adjustment,compared with the serum calcium(7.21,8.20)mg/dL group,the≤7.20 mg/dL group had a significantly increased risk of AKI(OR=1.242,95%CI:1.050-1.460,P=0.011).This association remained significant in patients aged≥65 years(OR=1.30,95%CI:1.06-1.58)and in patients with CCI<5(OR=1.39,95%CI:1.07-1.81).The RCS curve showed an approximately U-shaped relationship between serum calcium and AKI risk.The area under the ROC curve was 0.609(95%CI:0.592-0.626).The AUC of the combined prediction model incorporating serum calcium and estimated glomerular filtration rate(eGFR)increased to 0.687(95%CI:0.671-0.703).Conclusion Serum calcium≤7.20 mg/dL at ICU admission is an independent risk factor for AKI in HF patients.Its predictive efficacy alone is limited,but it can improve predictive value when combined with eGFR.It can serve as a convenient and economical preliminary screening indicator for AKI risk in HF patients in the ICU,particularly suitable for elderly HF patients and those with fewer comorbidities,providing a key time window for precise monitoring and early intervention in the ICU.
Keywords：serum calciumheart failureacute kidney injuryintensive care unitpredictorclinical translation
Publication Date：2026-02-20
Online Publishing Date：2026-03-16(First online date of this platform, not the publication date of the document)
Pages：6( 329-334 )