[Risk factors of postoperative acute kidney injury and the impact on outcome in non-senile patients undergoing cardiac valvular surgery].

Objective: To investigate the risk factors of postoperative acute kidney injury (AKI) in patients aged between 40 and 50 years old undergoing cardiac valvular surgery and the impact on outcome. Methods: The clinical data of 286 patients aged between 40 and 50 years old undergoing cardiac valve surgery in Guangdong Provincial People's Hospital from January 2012 to December 2016 were analyzed retrospectively. Preoperative coronary angiography was performed in all patients. All patients enrolled were divided into AKI group and non-AKI group according to the existence or not of postoperative AKI. Patients with AKI were further divided into AKI stage 1, stage 2, and stage 3 groups according to KDIGO guideline. Demographic characteristics, preoperative clinical data including serum creatinine, estimated glomerular filtration rate, hemoglobin, uric acid, urinary protein, presence or absence of chronic kidney disease, left ventricular ejection fraction, pulmonary artery pressure, New York Heart Association (NYHA) functional classification, preoperative co-morbidity (hypertension, diabetes, anemia, cerebrovascular disease, peripheral artery disease), preoperative medication(vasoactive drugs, diuretic, renin-angiotensin system inhibitor (RASI), surgical data (contrast dosage in coronary angiography, type of cardiac valve surgery) were recorded and analyzed in this retrospective study. The risk factors for postoperative AKI and its impact on clinical outcomes (mortality, hospitalization expenses and Intensive Care Unit stay duration) were evaluated. Logistic regression analysis was used to determine the risk factors for postoperative AKI and the adjusted variables with P<0.2 were selected for the multivariate logistic regression analysis to define the independent determinants for AKI. Results: AKI was defined in 106 out of 286 enrolled patients, including 96 patients with AKI stage 1, 10 patients with AKI stage 2 and no patients with AKI stage 3. The proportion of coexisting cerebrovascular diseases was higher in AKI group than in non-AKI group (9(8.49%) and 5(2.78%), χ(2)=4.677, P=0.031), while there was no difference among other baseline data between the two groups. Multivariate logistic regression analysis showed that preoperative complications of cerebral vascular disease was an independent risk factor of postoperative AKI (OR=3.578, 95%CI 1.139-11.242, P=0.029). Five out of 106 AKI patients died during hospitalization while there was only 1 patient died among 180 patients without AKI. Patients with AKI after cardiac valve operation experienced higher mortality than patients without AKI (χ(2)=5.625, P=0.028). Further analysis showed that there was no difference in hospitalization mortality between patients with AKI stage 2 and stage (χ(2)=0.686, P=0.408) while the hospitalization mortality in patients with AKI stage 2 was higher than those without AKI (χ(2)=8.113, P=0.004). The hospitalization expenses in patients with AKI were 10.38(8.59,12.54) ×10(4) RMB, significantly higher than that in patients without AKI (9.72(8.03,11.93) ×10(4) RMB)(P=0.043). There was no difference in hospitalization expenses between patients with AKI stage 1 and without AKI (P=0.635). The hospitalization expenses in patients with AKI stage 2 was higher than those without AKI (P=0.023). Intensive Care Unit stay duration in patients with AKI was 3(1,4) days, significantly higher than those without AKI (P=0.044). There was no difference in Intensive Care Unit stay duration in patients with AKI stage 1 and without AKI (P=0.978), while Intensive Care Unit stay duration in patients with AKI stage 2 was significantly longer than those without AKI (P=0.006). Conclusions: Preoperative complications of cerebral vascular disease is an independent risk factor of postoperative AKI. Non-senile patients with AKI after cardiac valvular surgery is associated with a higher proportion of mortality, hospitalization expenses and Intensive Care Unit stay duration as compared patients without postoperative AKI.