#1818 Association of combined systemic inflammatory indices with the severity and outcome of tunnelled hemodialysis catheter-related bacteremia
Authors: Roldán Deborah , León Mariana , Melero Eva López , Valcarce Eduardo Gallego , Gruss Enrique , Shabaka Amir 
Published: May 2024

Abstract

Background and Aims
Systemic inflammation plays a critical role in sepsis. Multiple inflammatory parameters have been used in clinical practice to diagnose and predict outcomes. More recently, systemic inflammatory indices derived from the complete blood count (CBC) such as the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR) and red blood cell distribution width (RDW) have shown a diagnostic and prognostic value in several critical infectious diseases such as pneumonia, endocarditis, osteomyelitis, COVID-19, severe sepsis and septic shock. The aim of our study was to evaluate NLR, PLR, LMR and RDW in tunnelled hemodialysis catheter-related bacteremia and investigate their predictive value regarding in-hospital mortality and 30-day survival.

Method
We performed a retrospective study that included patients with tunnelled hemodialysis catheters in our dialysis unit between January 2003 and March 2023 that presented with hemodialysis catheter-related bacteremia. Demographic data, comorbidities, dialysis vintage and catheter vintage and type were registered. The baseline systemic inflammatory indices (NLR, PLR, LMR and RDW) were calculated from the CBC at presentation of bacteremia. Primary outcome was in-hospital mortality and mortality after 30 days. Secondary outcomes were complications during follow-up such as development of septic shock, ICU admission, endocarditis or septic embolic complications, need for catheter removal and the time elapsed till blood cultures were negative.

Results
The study included 58 patients with tunnelled hemodialysis catheter-related bacteremia. Mean age was 63.8 ± 17 years, and median catheter vintage was 122 days (IQR 84-387). The main causative organism was Staphylococcus aureus in 29 (50%) of the cases, followed by Serratia marcescens (12.1%) and Staphylococcus epidermidis (6.9%). Four patients (6.9%) presented with septic shock, 7 patients (12.1%) developed endocarditis and/or septic emboli, and 47 patients (81%) required removal of the catheter. In-hospital mortality was 6.9% and 30-day mortality was 12.1%.
There was a positive correlation between NLR, PLR, LMR and RDW. NLR and RDW were significantly higher in Staphylococcus aureus bacteremia. In the regression analysis, higher tertile of NLR and RDW were associated with Staphylococcus aureus bacteremia. A NLR cutoff of &gt;7 was predictive of Staphylococcus aureus bacteremia (AUC 0.75 [95% CI 0.61-0.89], p = 0.005) with an 86% sensitivity and 60% specificity.
There were no differences in these inflammatory indices between survivors and non-survivors during hospital admission. However, RDW was significantly higher in patients who did not survive after 30 days (17.8% [15.7-19.4] vs 15.9% [15-17.1], p = 0.043). An RDW of &gt;16.9% was determined as the predictive cutoff value of 30-day mortality (AUC 0.73, 95% CI 0.54-0.92, p = 0.049) with a sensitivity of 71.4% and specificity of 70%.

Conclusion
In our cohort of patients with tunnelled hemodialysis catheter-related bacteremia, higher RDW was associated with a poor 30-day survival and a NLR &gt;7 was predictive of Staphylococcus aureus bacteremia. These results suggest that NLR may be useful as a diagnostic index of Staphylococcus aureus bacteremia and RDW can be used to predict 30-day mortality in hemodialysis catheter-related bacteremia.