Interleukin 18 as an early biomarker of acute kidney injury in critically ill patients

Abstract

Background: Acute kidney Injury (AKI) has long been recognized as a disease state associated with increased morbidity and significant mortality. This is held especially true in high risk groups like critically ill patients. For this reason it has been crucial to be able to detect and diagnose AKI early and institute management interventions to prevent progression into established AKland need for subsequent development of Acute Kidney Injury renal replacement therapy. Serum creatinine, which is currently used to diagnose AKI, has been noted to be insensitive to early AKI and has therefore brought the need for earlier biomarkers.

In this study, one such biomarker, urinary IL-18, is tested in its ability to predict the development of AKI in critically ill patients in Kenyatta National Hospital.

Main objectives: To compare urinary IL-18 to serum creatinine in the ability to predict the development of Acute Kidney Injury.

Specific objectives To determine the urinary IL-18 levels in critically ill patients and whether they relate to subsequent development of Acute Kidney Injury. To assess whether urinary IL-18 levels correlate with the degree of Acute Kidney Injury. To determine whether the urinary IL-18 levels would indicate short term prognosis in terms of morbidity and mortality.

Study design Prospective, observational study between two assay markers.

Study setting/population General population of critically ill patients in Kenyatta National Hospital.

Methods A total of 133 critically ill patients were recruited into the study. Minimal demographic data was obtained using a study transcription form. Additional information regarding diagnosis, daily variable of interest and outcomes were obtained from daily monitoring charts. Once informed conserﾷt was obtained, 10m Is of urine was obtained from a catheter sample for eventual determination of urinary IL-18 and daily sampling of 2mls venous blood was done to observe for the development of AKI. This was done at the KNH renal laboratory.

Data handling The data obtained from the laboratory was entered into a con',puter database. Spread sheets were generated on Excel and analysed using Windows SPSS version 17.

Results 62 of 110 patients went on to develop AKI giving a 56.4% incidence rate of AKI development in

Results The critical care units in Kenyatta National Hospital. There was a 52% mortality rate seen in this study. The distribution of patients with AKI was such that 79% were in stage 1 AKI, 8% were in stage 2 and 13% were in stage 3 AKI based on the AKIN criteria. Urinary Interleukin 18 showed a poor predictive ability for the development of AKI with an AUROCC of 0.564. However, urinary Interleukin18 showed a good predictive ability for mortality, (p<0.05), but was a poor predictive marker for morbidity.

CONCLUSIONS Urinary Interleukin 18 was a poor early biomarker for the development of AKI and morbidity. It was however a good predictive biomarker for mortality.

Recommendations Studies have been inconsistent about the use of urinary interleukin 18 as an early biomarker for the development of Acute Kidney Injury. It has however been proven as a benefictal predictive marker for mortality. lv10re research should be done to pursue the utility of urinary Interleukin 18 in AKI especially in the critically ill patient population.