Prospective Evaluation of the FUJIFILM SILVAMP Dengue NS1 Ag for Early Dengue Detection: A Multicenter Study in Thailand.

Early detection of dengue is crucial to prevent severe outcomes. This multicenter prospective cohort study evaluated the performance of the FUJIFILM SILVAMP Dengue NS1 rapid test (SILVAMP NS1) compared to a commercially available rapid NS1 test (non-SILVAMP NS1) and NS1 enzyme-linked immunosorbent assay (ELISA), using real-time reverse transcription polymerase chain reaction (rRT-PCR) as the primary reference standard. A total of 402 patients with acute febrile illness were enrolled across four hospitals in Thailand between March 2023 and September 2024. Clinical features and baseline laboratory data were recorded at admission, and diagnostic testing was performed on both whole blood and serum samples. Among participants, 47.5% tested positive for dengue by rRT-PCR, with DENV-2 being the most prevalent serotype. Against rRT-PCR, SILVAMP NS1 demonstrated 73.5% sensitivity and 99.4% specificity. Its sensitivity and specificity were statistically comparable to those of NS1 ELISA (78.1% and 100%; p = 0.092 and 1.000, respectively). SILVAMP NS1 outperformed non-SILVAMP NS1 in sensitivity (66.9%; p < 0.006) while maintaining equivalent specificity (100%; p = 1.000). Agreement between SILVAMP NS1 and NS1 ELISA was almost perfect, with a Cohen's κ of 0.90. The diagnostic performance of SILVAMP NS1 remained consistent across sample type, illness duration, serological status, and dengue serotype. In a subgroup analysis, finger-stick testing with SILVAMP NS1 maintained high specificity but exhibited reduced sensitivity. These findings demonstrate that SILVAMP NS1 provides reliable diagnostic performance with high specificity and strong concordance with NS1 ELISA. Its ease of use and applicability in point-of-care settings support its potential as a practical tool for early dengue diagnosis, particularly in resource-limited environments.