Triple positivity for nonstructural antigen 1, immunoglobulin M and immunoglobulin G is predictive of severe thrombocytopaenia related to dengue infection

Background: The early identification of patients at risk of severe dengue infection (DI) is critical to guide clinical management. Non-structural antigen 1 (NS-1), immunoglobulin M (IgM) and immunoglobulin G (IgG) are used routinely for the diagnosis of DI. Objectives: We sought to evaluate whether positivity for NS-1, IgM and IgG individually or together is predictive of severe complications of DI. Methods & materials: A prospective study was conducted among patients with DI admitted to our institution between 2014 and 2019. DI was diagnosed based on a positive NS1 or IgM. IgG was also tested on all the patients. Clinical data was obtained from electronic medical records at NH. Statistical analyses were performed using SPSS version 20. Results: We collected data on 3504 patients. Patients who were positive for NS1, IgM and IgG (triple positive: TP) were more likely to develop severe DI (63.8 %) in comparison to those who were only NS1 positive (single positive: SP) (3.0 %) and patients with positive NS1 and IgM (double positive: DP) (7.5 %). [p= 0.001]. Regression analysis confirmed that TP status on admission was predictive of severe complications. (p < 0.01). Receiver operator characteristic curve (ROC) analysis showed (AUC: 84.8; sensitivity = 90.7 and specificity = 83.2) that TP status on admission is predictive of thrombocytopenia on day 5. The predictive power of TP status was superior to that of NS1 and IgG positivity. Conclusions: We propose that TP status on admission is a novel predictive factor for severe DI. Further studies are required to explore the biological basis for this finding.