A-274 Performance of Laboratory Tests for the Diagnosis of Dengue in Regions with a High Number of Cases. Study of 2023 to 2024

Abstract Background Early and accurate laboratory diagnosis of Dengue is essential for appropriate patient management. Virus detection and serological conversion have been the main targets of diagnostic evaluation for many years; however, cross-reactivity of antibody responses between flaviviruses has been a confusing problem in providing a differential diagnosis. The lack of reliable biomarkers that provide an effective indicator of severe disease progression means that in an epidemic outbreak of Dengue, the diagnostic suspicion is based essentially on the clinical picture and some hematological alterations. However, in regions where the incidence of the disease is lower, cases can be more challenging, simulating other types of viruses. Furthermore, confirmatory tests, such as the dosage of serum antibodies of the IgM class and the detection of the NS1VD antigen, are not always available. The fact is that the Dengue epidemic that occurred in Brazil last year exposed the need for rapidly accessible and low-cost parameters that corroborate the diagnosis, especially in the mildest cases. The authors aimed to evaluate the performance of the most widely used available tests and the agreement between the Hemogram and serological tests for Dengue disease. Methods This study was based on a retrospective database of a large clinical laboratory in São Paulo, Brazil, analyzing results between January 2023 and December 2024. A total of 63,009 tests requested with suspected dengue from were analyzed. 54.8% were female, adults aged 19 to 59 years (64.0%). The most accessible (specific) serological tests for the population were considered: DNG-G, DNG-M, NS1VD and the Hemogram, with emphasis on blood parameters such as platelets. Statistics: Chi-square tests were followed by analysis of adjusted standardized residuals (Pearson residuals) to identify in which categories the observed frequencies differed from those expected, with the Kappa test to determine agreement between the Hemogram and serological tests. Results The Hemogram showed 4.3% of positivity or suspicion for Dengue with platelets below 100,000 platelets/mm3. For serological tests of positivity was respectively, NS1VD(34.6%), DEN-G(20.1%), and DEN-M( 26.2%). , the levels of agreement Kappa, compared to thrombocytopenia were respectively NS1VD(66.6%), DENG-G(79.6%) and DENG-M(74.8%). Considering the NS1VD test as the gold standard test for Dengue, the agreements were: DENG-G(74.0%), DENG-M (65.7%) and Thrombocytopenia (66.0%). There were moderate agreements (p=0.068) between the tests. Conclusion The results showed that there is not specific biomarker for the diagnosis of Dengue that is present during all in the periodic of disease in the patient. The results presented showed moderate agreement between them. It would be recommended to have a combination of blood count with a point of care antigen or antibody test, such as NS1VD or DENG- M which had greater concordances. These rapid tests have greatly simplified the laboratory diagnosis of Dengue. Despite these advances, challenges remain in the clinical management of infected patients.