Laboratory evaluation of the Chembio DPP Syphilis Screen & Confirm point-of-care test on serum and simulated blood samples
Bibliographic record
Abstract
Introduction: Syphilis infections are increasing in Canada, and traditional serological diagnostics pose barriers for vulnerable and marginalized populations at greatest risk. Point-of-care tests (POCTs) offer solutions, yet none were available in Canada until recently. The Chembio Dual Path Platform (DPP) Syphilis Screen & Confirm (SSC) is one of the first POCTs that helps distinguish active infection from non-infectious syphilis. This study evaluates the reliability of the Chembio DPP SSC to diagnose syphilis infection. Methods: One hundred clinical samples with known syphilis serology (chemiluminescent microparticle immunoassay [CMIA] and rapid plasma regain [RPR]) results were used to evaluate the Chembio DPP SSC. CMIA-ve (n = 20), CMIA+ve RPR-ve (n = 40), and CMIA+ve RPR+ve (n = 40) samples represented negative, past, and presumed active infection, respectively. Samples were used in two formats: serum and simulated blood. Two laboratory technicians read the test visually, and with the manufacturer's DPP Micro Reader, in blinded fashion. Results: Overall sensitivity of the Chembio DPP SSC to distinguish presumed active infection from non-infectious syphilis (past infection and no infection) with visual reads were 52.50% (serum) and 55.00% (simulated blood). Sensitivity increased using the DPP Micro Reader to 90.00% (serum) and 97.50% (simulated blood). Specificity with visual reads were 98.33% (serum) and 95.00% (simulated blood) compared to Micro Reader results of 88.30% (serum) and 80.00% (simulated blood). For the non-treponemal portion of the POCT with visual reads, the sensitivity increased with increasing RPR titers. Low RPR titers <1:4 only had a sensitivity of 42.86% (serum) and 14.29% (simulated blood). Discussion: The laboratory evaluation of the Chembio DPP SSC shows promise in detecting active syphilis, particularly in samples with RPR titers >1:4. However, the need for the Micro Reader for more accurate results is a limitation of the POCT, and financial constraints may pose barriers to some users. Further field evaluation is warranted.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".