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Red blood cell distribution width predicts acute kidney injury after cardiac surgery in elderly patients: A retrospective cohort study

Background: This retrospective cohort study was conducted to explore the association between Red- Blood-Cell Distribution Width (RDW) and Acute Kidney Injury (AKI) among old patients after cardiac surgery.

Methods: Data from consecutive old patients who underwent cardiac surgery with cardiopulmonary bypass were retrospectively analysed according to the inclusion and exclusion criteria. The primary outcome was AKI within the first postoperative day. Multivariable logistic regression and Receiver’s Operating Characteristic (ROC) curves were used to explore the association between RDW and AKI among old patients after cardiac surgery.

Results: The AKI patients had significantly larger RDW compared with non-AKI patients (14.7 ± 0.9 vs. 13.4 ± 0.6). Multiple logistic regression showed the second quartile was not associated with the risk of AKI after cardiac surgery (OR=1.05, 95% CI: 0.72-1.53) compared with the lowest quartile. However, the patients with the third quartile (OR=1.90 95% CI: 1.27-2.83) and fourth quartile (OR=2.03 95% CI: 1.66-4.86) of RDW had higher risk of AKI after cardiac surgery. The area under the ROC curve was 0.766. At the cut-off value of 13.9, the sensitivity was 69.4% and specificity was 68.6%.

Conclusion: RDW is a novel risk predictive factor of AKI after cardiac surgery in old Chinese patients. Physicians should consider the possible occurrence of AKI and apply a pre-emptive therapy for these patients.

Author(s): You Xia, Dong Chen, Lin Li