PLATELET-TO-LYMPHOCYTE RATIO IN PAEDIATRIC INTENSIVE CARE: LOWER PLR AND ITS INVERSE ASSOCIATION WITH HAEMATOLOGICAL ORGAN DYSFUNCTION

Abstract

Background: The platelet-to-lymphocyte ratio (PLR) is an inexpensive biomarker derived from the complete blood count and has been widely evaluated as a prognostic indicator in adult infectious diseases. Prognostic direction and clinical utility of PLR in paediatric intensive care, particularly in settings with a high burden of viral illness and thrombocytopenia, remain insufficiently defined. This study evaluated the prognostic utility of admission PLR in children admitted to a tertiary care paediatric intensive care unit (PICU) with acute infectious diseases and examined its relationship with haematological organ dysfunction. Methods: A prospective observational study was conducted over 18 months (May 2023 to November 2024) in a tertiary care PICU in North India. One hundred children aged 1 month to 18 years admitted with acute infectious diseases were enrolled after application of predefined inclusion and exclusion criteria. PLR was calculated from the admission complete blood count and analysed in relation to in-hospital mortality, organ dysfunction assessed by the PELOD-2 score, and duration of PICU and hospital stay. Non-parametric statistical tests were used where appropriate. Results: Contrary to the expected adult-derived pattern, median PLR was significantly lower among non-survivors [28.05 (IQR: 5.35-63.88)] than among survivors [102.76 (IQR: 51.79-176.14)] (p < 0.01). Receiver operating characteristic analysis showed an AUC of 0.168 for PLR as a mortality predictor, below the chance line, with sensitivity of 16.67% and specificity of 58.51%. PLR demonstrated a moderate, statistically significant negative correlation with the haematological PELOD-2 sub-score (r = -0.473, p < 0.001). No significant association was observed with PICU or total hospital length of stay. Conclusion: PLR showed an inverse prognostic direction in paediatric PICU patients which comprised of substantial burden of viral illnesses. The negative association with haematological dysfunction is likely to reflect consumptive thrombocytopenia in severe viral illness, particularly dengue. Potential clinical value of PLR may lie in identifying haematological severity in selected viral and thrombocytopenic contexts.