Correlation analysis between homocysteine level and acute kidney injury after cardiac valve replacement surgery

Objective To investigate the relationship between preoperative serum homocysteine (Hcy) level and acute kidney injury (AKI) after cardiac valve replacement surgery. Methods The data of the inpatients who accepted cardiac valve replacement surgery, age ≥18 years, no renal replacement therapy before surgery, non-renal decompensation and preoperative serum creatinine (Scr)＜178 μmol/L, survival within 48 h after surgery, and with preoperative serum Hcy data in the First Affiliated Hospital of Guangxi Medical University from January 1, 2015 to December 31, 2017 was retrospectively analyzed. AKI was diagnosed in patients whose Scr increased more than 26.5 μmol/L (0.3 mg/dl) within 48 hours or 1.5 times higher than baseline within 7 days after surgery. According to this, patients were divided into AKI group and non-AKI group, and the affecting factors for AKI were compared between the two groups. Multivariate logistic regression was used to analyze the independent influencing factors of AKI. The relationship between serum Hcy level and AKI incidence was analyzed by Spearman correlation analysis. Whether the AKI occurred and serum Hcy levels were used as variables to map the receiver operating characteristic curve (ROC), and was used to assess the value of preoperative serum Hcy level for predicting AKI after cardiac valve replacement surgery. Results A total of 810 subjects were included in the study, including 375 males and 435 females. They were (50±11) years old (19-78 years old). Among them, 329 patients with AKI occurred within 7 days after heart valve replacement, and the incidence rate was 40.6% (male 45.9%, female 36.1%). The serum Hcy level in the AKI group was higher than that in the non-AKI group [(15.74±4.55) μmol/L vs (13.87±3.85) μmol/L, t=6.106, P＜0.01]. Multivariate logistic regression analysis showed age (OR=1.030, 95%CI 1.014-1.045, P＜0.001), extracorporeal circulation time (OR=1.011, 95%CI 1.007-1.016, P＜0.001), Scr (OR=1.014, 95%CI 1.005-1.023, P=0.002), serum Hcy (OR=1.059, 95% CI 1.017-1.103, P=0.006), high level of Hcy (＞13.64 μmol/L) (OR=1.465, 95%CI 1.059-2.027, P=0.021) and moderate to severe hyperhomocystinemia (16≤Hcy≤100 μmol/L) [with normal HHcy (Hcy＜10 μmol/L) as reference, OR=2.180, 95%CI 1.245-3.816, P=0.006] were independent influencing factors of AKI after cardiac valve replacement surgery. Spearman correlation analysis showed that the incidence of postoperative AKI increased with the increase of preoperative serum Hcy level (rs=0.927, P＜0.001). The results of ROC curve showed that the area under the curve of the preoperative serum Hcy level predicting AKI after heart valve replacement was 0.701, and the cutoff value was 13.64 μmol/L, with the sensitivity 61.3%, specificity 70.9%. Conclusions Preoperative serum Hcy level is an influencing factor for AKI after cardiac valve replacement surgery. The higher the level of preoperative serum Hcy, the higher the incidence of AKI after cardiac valve replacement surgery. Patients with preoperative serum Hcy levels＞13.64 μmol/L have an increased risk of AKI after cardiac valve replacement surgery.