The predictive value of red blood cell distribution width and platelet-to -lymphocyte ratio for acute kidney injury in critically ill patients

Background: Red blood cell distribution width (RDW) and the platelet-to-lymphocyte ratio (PLR) are associated with different types of prognoses in critically ill patients. But, the value of RDW and PLR in predicting the occurrence of acute kidney injury (AKI) in critically ill patients are unknown. The purpose of the study was to explore the associations of RDW and PLR with AKI incidence. Methods Among 1500 adult patients in the intensive care unit (ICU) between January 2016 and December 2019 were enrolled, we examined the associations of baseline RDW and PLR with the risk of AKI development using logistical analysis. In addition, we explored the value of RDW and PLR in predicting in-hospital mortality. Results The study participants included 951 men and 549 women, aged 60.1±16.14 years. The subjects had a mean RDW of 14.65±2.14% and a mean PLR of 188.16±129.2. Overall, 615 (41%) patients were diagnosed with AKI. There were remarkable differences in RDW and the PLR between the AKI and non-AKI groups ( P <0.001). After adjustment, the association of RDW with AKI development risk strengthened (OR: 1.28, 95% CI: 1.19-1.36). Moreover, we divided the groups into two subgroups each; the high-RDW (≥14.045%) group had a high risk of developing AKI (OR=5.189, 95% CI: 4.088-6.588), while the high-PLR(≥172.067)group had a risk of developing AKI (OR=9.11,95% CI:7.09-11.71). The areas under the receiver operating characteristic curves (AUCs) for the prediction of AKI incidence based on RDW and PLR were 0.780 (95% CI: 0.755-0.804) and 0.728 (95% CI:0.702-0.754) (all P < 0.001), with cut-off values of 14.045 and 172.067, respectively. Moreover, a higher RDW was associated with a higher rate of hospital mortality (OR: 2.907, 2.190-3.858), and the risk of in-hospital mortality related to PLR was 1.534 (95%CI: 1.179-1.995). The AUC for in-hospital mortality based on RDW was 0.663 (95%CI:0.628-0.698), while the AUC for in-hospital mortality based on the PLR was 0.552 (0.514-0.589). Conclusions A higher RDW related to a higher risk of the occurrence of AKI and in-hospital mortality in ICU.The PLR also showed predictive value for the occurrence of AKI but did not show any clear prediction value of in-hospital mortality.