Application of Haematological Indices in the Diagnosis of Swine Influenza Infection in Adults

Abstract

Introduction: The differential diagnoses of patients hospitalised for Influenza-Like Illness (ILI) due to swine influenza virus vs other pathogens are challenging. Aim: To evaluate haematological indices such as lymphocyte (LYM), platelet (PLT), Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR), and Lymphocyte multiplied by Platelet Count (LYM×PLT) as potential indicators to discriminate swine influenza virus infection from another ILI in Adults. Materials and Methods: This study was conducted among 332 patients, admitted with ILI from January 2019 to December 2019. Complete Blood Count (CBC) and Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) to detect swine influenza virus from throat/nasal swab were performed in each patient. Based on results, patients were divided into swine influenza-positive and swine influenza-negative groups. ANOVA test was used to compare different groups. The diagnostic values of the haematological indices in swine influenza infection were evaluated, using the ROC curve. p-value <0.05 was considered statistically significant. Results: The haematological indices in patients with swine influenza-positive were significantly different as compared to swine influenza-negative and healthy control groups. Additionally, among all the haematological indices, NLR showed the highest diagnostic value with the Area Under the Curve (AUC) of 0.511 with the best sensitivity and specificity of 55.1% and 48.1%, respectively, if the swine influenza-negative group was used as a reference. Whereas, using controls as a reference, the AUC of NLR was 1.0 with the best sensitivity and specificity of 100% each. The best sensitivity and specificity of PLR was 46.1% and 46.9%, if the swine influenza-negative group was used as a reference. Conclusion: Combination of the NLR values more than 3.09 and the PLR values more than 130.53 may indicate swine influenza infection in adults. NLR and PLR value can be used to ascertain, whether the patient who presented as ILI, is infected with Swine Influenza.