Quantifying the Kinetics of Hematocrit and Platelet Count in Febrile Phase to Develop a Scoring System for Predicting Dengue Shock Syndrome in Adults: A Matched-case Observational Study from a Hospital in Viet Nam

Introduction Early prediction of dengue shock syndrome (DSS) is crucial for patient triage and management. The lack of consensus regarding the precise definition of the laboratory warning sign (WS) "increase in hematocrit concurrent with rapid decrease in platelet count" made it difficult to use all the WS for prediction DSS. Methods A matched case observational study was conducted in adult dengue patients hospitalized during the first 4 days of illness from November 2022 to August 2023, of whom 1 DSS case was matched with 3 non-DSS ones. Results There were 448 patients (112 DSS and 336 non-DSS) in this study. An increase in hematocrit concurrent with a rapid decrease in platelet count was found to occur 1 - 2 days prior to the development of DSS. The cut-off value of an increase in hematocrit by ≥ 5% concurrent with a decrease in platelet count by ≥ 50% as compared with those of the previous day was predictors of DSS, with a sensitivity of 60.71% and a specificity of 83.04%. A DSS scoring system developed from these two cut-off values plus number of clinical warning signs could be used to predict risk of DSS in adult patients with an area under the receiver operating characteristic curve of 0.93, sensitivity of 86.6%, specificity of 87.8%. The Score allows triage patients into low-, intermediate-, and high-risk groups for appropriate monitoring and management. Conclusions The warning sign "increase in hematocrit concurrent with rapid decrease in platelet count" can be defined as " an increase in hematocrit ≥5% concurrent with a decrease in platelet count ≥50% compared with those of the previous day". The DSS score developed from traditional warning signs are served as good predictors for DSS in adult patients.