273: THE PREDICTIVE VALUE OF PLATELET INDICES IN DETERMINING MORTALITY IN CRITICALLY ILL CHILDREN

Introduction: Platelet indices such as platelet count (PLT), mean platelet volume (MPV), platelet mass index (PMI), platelet crit (PCT), and PLT/MPV ratio are commonly altered during critical illnesses, yet their prognostic significance remains unclear. This study sought to assess the predictive value of platelet indices upon admission for mortality in critically ill children. Methods: After IRB approval, in a retrospective single institutional study, we examined children (excluding neonates) admitted to the PICU. This is a secondary analysis of data on critically ill children included in another study. Demographic, clinical, platelet, and outcome data were compared between the deceased and survivors using Mann-Whitney U and the Chi-square tests. To evaluate the predictive value, we constructed ROC curves, utilizing various platelet indices as the predictor variables for mortality. Results: We analyzed 741 children with a median age of 104 (24-183) months and 54% males. The hospital LOS was 8 (4-18) days, and the overall mortality rate for the cohort was 11.2%. In this cohort 25.8% received mechanical ventilation, 51.7% required fluid boluses, and 17.7% received vasoactive medications. The median [IQR] values of PLT (135 [53-270] vs. 250 [152-343]), PMI (1404 [581-2587] vs. 2848 [1675-3440]), PCT (0.14 [0.05-0.25] vs. 0.24 [0.16-0.34]), and PLT/MPV (14.1 [4.5-24.5] vs. 24.8 [14.4-35.6]) were lower in the deceased compared to survivors (p< 0.05). The median MPV was similar in both groups. The AUC [95% CI] for various platelet indices against mortality were - PLT: 0.314 ([0.247-0.382], p< 0.001), PMI: 0.313 ([0.247-0.379] p< 0.001), PCT: 0.313 ([0.247-0.379], p< 0.001), and PLT/MPV: 0.318 ([0.250-0.387], p< 0.001). Conclusions: In critically ill children, the platelet indices, PLT, PMI, PCT, and PLT/MPV demonstrate a moderate accuracy for predicting mortality. MPV has poor discriminatory value. The discriminating value of various platelet indices in specific illnesses in children needs further exploration.