How often did syphilis tests have corresponding HIV tests in Ontario, Canada? A retrospective analysis of comprehensive laboratory data
Bibliographic record
Abstract
ABSTRACT Objectives Canadian guidelines recommend HIV testing for individuals being evaluated for syphilis. Our objective was to examine three aspects of HIV testing (i.e., if a HIV test occurred, timing of HIV test in relation to syphilis test, and the proportion with a positive HIV test result) among syphilis tests between 2017 and 2022 from individuals with no evidence of a previous HIV diagnosis. Design and setting This study is a retrospective analysis of comprehensive laboratory testing data from Ontario’s provincial public health laboratory. Participants Direct fluorescent antibody (DFA) and serological non-prenatal syphilis tests from January 1, 2017 to December 31, 2022, from individuals aged ≥15 years with no evidence of a previous HIV diagnosis (N = 3,001,058 total tests). Positive syphilis tests were categorized using the rapid plasma reagin (RPR) titre as “current” (DFA+/RPR ≥1:8) or “historical” (RPR <1:8). Exposure categories were assigned using individually-linked HIV exposure category data retrieved from the laboratory’s HIV database. Primary and secondary outcome measures Number and proportion of syphilis tests that had a corresponding HIV test on the same day or within 7/28/90/180 days, and among those with an HIV test within 28 days, number and proportion that had an HIV-positive test result. Results From 2017 - 2022, 1,516,726 and 1,484,332 syphilis tests among males and females, respectively, were included in the analysis. Individuals with a positive syphilis result were less likely to be tested for HIV within 28 days of their syphilis test compared to those with a negative syphilis test result (74.7% versus 91.1% in males, 97.5% CI [-0.17, -0.16], 65.2% versus 92.4% in females, 97.5% CI [-0.28, -0.26]). Males with “current” positive syphilis test results were less likely than males with “historical” positive syphilis results to be tested for HIV within 28 days (69.1% versus 76.6%, 97.5% CI [-0.084, -0.066]); this was not true in females (67.1% versus 64.4%, 97.5% CI [0.0062, 0.049]). Males overall and males with “current” syphilis were more likely to be diagnosed as HIV-positive (p<0.025). Conclusions Most individuals who tested for syphilis at PHO were also tested for HIV, though those positive for syphilis were less likely to be tested, representing an opportunity for enhanced HIV testing. Ensuring that syphilis-positive individuals are tested for HIV may identify previously undiagnosed individuals living with HIV.
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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 | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.010 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".