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Acute Kidney Injury (AKI) is a common complication among patients admitted to the hospital. The incidence of AKI in critical illness is 20-50%, and the condition has a high mortality rate. The methods for measuring most biomarkers are expensive and might not be suitable in daily practice. The neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) are accessible ratios that can be used to estimate mortality in patients with acute kidney injury al entering an intensive care unit. The objetive of the study was to determine the relationship between NLR and PLR and mortality in critically ill patients with acute kidney injury.
Observational, prospective, descriptive study conducted at a tertiary hospital from June 2020 to December 2021. The study included patients with severe sepsis, acute kidney injury, and mechanical ventilation with PaO2/FiO2 <150 mmHg. Patients were categorized into NLR >9.9 or <9.9 and PLR >250 or <250 upon admission to the intensive care unit. Follow-up was conducted for 30 days, and mortality was analyzed using Kaplan-Meier survival curves. Quantitative variables with normal distribution were analyzed using Pearson's correlation coefficient, and linear regression analysis was performed to predict mortality. Sensitivity and specificity for mortality were also analyzed using ROC curves. All analyses were performed with SPSS Statistics, version 26.
A total of 58 patients were included (45 males [77.6%]) with a mean age of 58.4 ± 10.7 years, and 18 (31%) required hemodialysis. NLR >9.9 determined a 30-day survival of 18% (RR 1.7; 11.5-18.5, p = 0.02) compared to 33% for NLR <9.9 (Figura 1). PLR >250 determined a 30-day survival of 16% (RR 2.09; 95% CI 10-18; p = 0.02) compared to 30% for PLR <250 (Figure 2). Pearson's correlation coefficient revealed a positive correlation between serum creatinine at admission and elevated NLR (Table 1; R 0.30; p = 0.018). Linear regression analysis did not identify any predictors of mortality. Sensitivity of 70% and specificity of 40% (AUC 0.48) were estimated for mortality with NLR >9.9, and for PLR >250, sensitivity was 60% with specificity of 56% (AUC 0.40).
NLR and PLR >9.9 and 250, respectively, determined lower 30-day survival in critically ill patients. Additionally, a positive relationship was observed between creatinine and NLR >9.9.