Diagnostic performance of the dengue Ag NS1 rapid test in Peruvian adults with suspected dengue virus infection

Dengue, transmitted by Aedes aegypti , remains a critical public health challenge in tropical regions, with Peru experiencing upsetting increases in cases. Rapid immunochromatographic tests for NS1 antigen detection are vital in resource-limited settings, but their performance must be validated against gold-standard methods like RT-PCR. To determine the sensitivity, specificity, and diagnostic accuracy of the OnSite ® Dengue NS1 rapid test compared to RT-PCR in a high-prevalence setting. A cross-sectional study analyzed 140 serum samples from suspected dengue cases (2021–2022) stored at -70 °C. RT-PCR served as the reference standard. Sensitivity, specificity, predictive values, AUC-ROC, and Cohen’s kappa were calculated using Stata v18. We found a mean age of 32.2 years, and 54% of the participants were woman. We assessed a dengue prevalence of 51.4% by RT-PCR. The rapid test detected NS1 with 88.89% sensitivity (95% CI: 79.28–95.08) and 100% specificity (95% CI: 94.72–100). The AUC was 94.44% (90.79–98.10), indicating high diagnostic accuracy. Concordance with RT-PCR was excellent (κ = 88.6). The test showed 94.29% overall accuracy, with 100% positive predictive value and 89.47% negative predictive value. However, 11.1% (8/72) of PCR-confirmed cases were false negatives. No false positives occurred. Most samples were collected 3–5 days post-symptom onset, aligning with peak NS1 detectability. The CTK Biotech OnSite ® Dengue NS1 rapid test demonstrated high specificity and moderate sensitivity, making it a reliable tool for dengue screening in endemic areas. Its performance supports its use in resource-limited settings, though false negatives underscore the need for complementary testing in clinically suspicious cases.