427: BLOOD CELL-FREE DNA (CFDNA) ANALYSIS FOR DIAGNOSIS OF INFECTIONS AND OUTCOMES IN THE PEDIATRIC ICU

Abstract

Introduction: Severe infections requiring ICU care warrant prompt diagnosis and initiation of treatment. Most conventional tests (CT) for infectious diagnosis have variable sensitivity, specificity and turn-around times. There is a need for a test with high sensitivity, specificity and shorter time to result in order to facilitate management decisions in critically ill patients. Cell free DNA (cfDNA) analysis - Karius test (KT) is emerging as an effective tool for early diagnosis of infections. However, there is a lack of sufficient data on KT in critically ill children. Our study aimed at evaluating the utility of KT for diagnosis of infections and outcomes in Pediatric ICU (PICU). Methods: Our retrospective study included children between 0 to 21 years of age who were admitted to our PICU between January 2019 and April 2022 and who had KT and CT done during PICU stay. Demographic, clinical, treatment, and outcome data were collected. KT and CT results were analyzed to determine their agreement and impact on diagnosis and management. Comparisons were made between PICU patients with positive KT and CT and those with only positive KT using student t-test (significant p≤0.05). Results: Among 67 PICU patients identified, the median (IQR) age was 96 (24-156) months, with 55% males and 93% hispanic; 41 (61%) had a positive KT with median (IQR) turn-around time for KT result 2.3 (2.1-3.1) days. KT confirmed diagnosis independently in 13 (19%) while in 20 (30%) patients, KT matched CT results and both KT and CT confirmed absence of infection in 20 (30%). KT facilitated the diagnosis and management of infections (initiation/change/discontinuation of antimicrobials) in 53/67 (79%) PICU patients. The overall survival was 98% in our cohort. The median (IQR) hospital length of stay (LOS) in our cohort was 14.5 (9-25) days. There was a significant difference in LOS among those PICU patients who had positive KT and CT versus those with positive KT and negative CT (p=0.03). Conclusions: Our study highlights the utility of blood cfDNA (Karius) test for microbiologic diagnosis amongst critically ill children. In a significant proportion (79%) of PICU patients, KT facilitated the decision regarding antimicrobials in critically ill children with a relatively short turn-around time for diagnosis.