Diagnostic Accuracy of Platelet Indices as a Marker for Sepsis in Neonates: A Case-control Study

Introduction: Diagnosis of sepsis in neonates is challenging due to overlapping of signs and symptoms. Currently blood culture and sepsis screen are used for diagnosis. Blood culture is the gold standard but its usefulness is limited due to low positivity, delay in reporting. Sepsis screen has variable sensitivity and specificity. To overcome these limitations, platelet indices can be used in diagnosis. Aim: To assess platelet indices as a marker to diagnose neonatal sepsis and to calculate sensitivity and specificity of platelet indices in comparison to clinical symptoms, sepsis screen and blood culture. Materials and Methods: This case-control study was conducted from June 2021 to November 2021 in Neonatal Intensive Care Unit (NICU) of tertiary care centre, Karnataka, India. Total of 198 neonates with signs and symptoms of sepsis and/or risk factors of sepsis were included. Weight and gestational age matched 198 healthy neonates served as control. Investigations include blood culture, sepsis screen and platelet indices were sent. Platelet indices were compared between cases and controls. Sensitivity and specificity of platelet indices were calculated in culture positive, screen positive and both negative groups. Data of both the groups were compared using Independent t-test and Chi-square test. Results: Demographic profile was homogenous between both study groups. Out of 198 cases, 145 (73.2%) had platelet count <1.5 lakhs, 132 (66.7%) had Mean Platelet Volume (MPV) >10.8 fl and 109 (55.05%) had Platelet Distribution Width (PDW) >19.1 fl. These values were statistically significant (p-value<0.001) when compared with controls. Statistically significant (p-value <0.001) difference was seen in mean of platelet count (1.3±0.7 lakhs/ cumm), MPV (10.7±0.8 fl), PDW (19.1±2.3 fl) and Plateletcrit (PCT) (0.1±0.1) between cases and controls. Platelet count was more sensitive (73.2%) and specific (81.3%) marker when compared between cases and controls. Conclusion: Platelet indices are cheaper and widely available markers in diagnosing neonatal sepsis. Thrombocytopenia, high MPV and high PDW were associated with neonatal sepsis.