The diagnosis of syphilis continues to rely on two types of serological tests: non-treponemal (NT), used as an initial screening, and treponemal (T), used as confirmatory tests. However, the relationship between both types and their ability to accurately detect the infection remains under analysis, especially in contexts where transfusion safety is critical. With this purpose, Verónica Aguaiza, Bq, and Rosa Chiriboga, MPH, from the Reference Unit for Blood Banks (URBS), evaluated 384 initially reactive samples using VDRL, and subsequently subjected them to VDRL, ELISA, CLIA, and FTA-ABS as the confirmatory reference. The study showed that concordance between NT and T tests was moderate, reaching percentages between 76% and 83%, and that this concordance decreased even further when compared to FTA-ABS, with values ranging from 44.2% to 61.9%. Although all tests demonstrated high sensitivities, significant differences emerged in their predictive value: VDRL presented the highest rate of false positives (up to 94.52%), while the automated treponemal CLIA test achieved the best positive predictive value (95.27%) and the strongest overall performance.

These results challenge the historical reliance on non-treponemal tests as the first diagnostic filter, as their isolated use may lead to misdiagnoses and imprecise clinical decisions. These findings strengthen the urgency of updating diagnostic and transfusion algorithms in the country, integrating automated treponemal tests that ensure more reliable detection, reduce false positives, and reinforce public health safety.

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Read the full article at: https://revistabiomedica.org/index.php/biomedica/article/view/7453