Quantifying the kinetics of hematocrit and platelet count during febrile phase to develop a scoring system for predicting dengue shock syndrome in adults: A matched case - control study from a Hospital in Viet Nam

INTRODUCTION: Early prediction of dengue shock syndrome (DSS) is crucial for effective patient triage and management. However, the lack of consensus regarding the precise definition of the laboratory warning sign (WS) -"an increase in hematocrit concurrent with a rapid decrease in platelet count"- has made it difficult to utilize this WS for predicting DSS. METHODS: A matched case - control study was conducted among adult dengue patients (aged ≥16 years) hospitalized within the first four days of illness between November 2022 and August 2023, with each DSS case was matched with three non-DSS ones. RESULTS: There were 448 patients (112 DSS and 336 non-DSS) included in this study. An increase in hematocrit concurrent with a rapid decrease in platelet count was observed 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 found to be a predictor of DSS, with a sensitivity of 60.71% and a specificity of 83.04%. A DSS scoring system developed using these two cut-off values, along with the number of clinical WSs, can be used to predict the risk of DSS in adult patients. It achieved an area under the receiver operating characteristic curve (AUC) of 0.93 (95% CI: 0.90-0.96), sensitivity of 86.6%, and specificity of 87.8%. The Score enables triage of patients into low-, intermediate-, and high-risk groups for appropriate monitoring and management. CONCLUSIONS: The WS "an increase in hematocrit concurrent with a rapid decrease in platelet count" can be defined as "an increase in hematocrit ≥5% concurrent with a decrease in platelet count ≥50% compared to the previous day". The DSS score, developed from traditional WSs, serves as a good predictor of DSS in adult patients.