The platelet-lymphocyte ratio is a promising predictor of early postoperative acute kidney injury following cardiac surgery: a case-control study

BACKGROUND: Acute kidney injury (AKI) is a common complication following cardiac surgery. This study explored the correlation between hematological biomarkers and the occurrence of postoperative AKI following cardiac surgery. METHODS: This was a retrospective case-control, single-center study. This study enrolled 91 patients who underwent cardiac surgery with cardiopulmonary bypass (CPB) support in Guangdong Provincial People’s Hospital Zhuhai Hospital between March 2019 and July 2021. The baseline serum creatinine levels of the patients was <132.6 µmol/L. The patients’ electronic medical records were retrospectively reviewed. AKI was diagnosed according to the Kidney Disease Improving Global Outcomes (KDIGO) 2012 Acute Kidney Injury Guideline criteria. Patients who sustained AKI in the 48 hours following cardiac surgery were categorized as Group A (n=48), while patients with normal serum creatinine levels postoperatively were categorized as Group B (n=43). The baseline demographic and clinical characteristics of the two groups were compared. Univariate analysis was performed to evaluate the correlation between biomarkers and postoperative AKI. Multivariate logistic regression was performed to identify the predictors of AKI following cardiac surgery. RESULTS: Forty-eight patients were diagnosed with AKI during the first 48 hours after cardiac surgery, while 43 patients were found to have normal creatinine levels postoperatively. Multivariate logistic regression analysis revealed advanced age (P=0.007), preoperative increased creatinine (P=0.023), duration of intraoperative hypotension (P=0.027), and the platelet-lymphocyte ratio (P/LR; P=0.042) as predictors of AKI following cardiac surgery with CPB. This study was performed in a single center, which might not be generalized to whole population. Ongoing review and modification of the surgical protocols may contribute to bias of the study. CONCLUSIONS: The P/LR can be obtained from a routine blood test, and may potentially be utilized as an independent indicator of AKI following cardiac surgery.