Evaluating HIV Rapid/Point of Care Testing among Risk Factor Groups in Ontario, 2011 to 2018
Bibliographic record
Abstract
OBJECTIVES: In 2014, Ontario's Point-of-Care (POC) test providers were advised to focus efforts on provincially defined priority populations who experience a greater risk of HIV. Our objective was to describe the POC program before, during and after this change, including tester characteristics, follow-up testing results, positive predictive value (PPV) over time, and trends and characteristics of those with reactive test results without a confirmatory serological specimen. METHODS: Test-level data of POC screening and confirmatory results were extracted from the Public Health Ontario HIV Datamart. Final test results were defined based on results of the confirmatory blood sample, or the POC test for "non-reactive" tests. Testing volumes, percent of total tests, percent positivity and PPV were calculated overall, annually, and by exposure group. RESULTS: Overall testing volumes decreased by 39.8% between 2014 and 2018. The majority of confirmed positive tests were in the men who have sex with men (MSM) exposure category, followed by HIV-endemic and heterosexual - no identified risk (heterosexual-NIR). Overall percent positivity decreased from 0.59% in 2011 to 0.42% in 2015 (change of 0.17%, 95% CI 0.03% to 0.31%), increasing to 0.69% in 2018 (change of 0.27%, 95% CI 0.20% to 0.34%). Increases in percent positivity corresponded with a decrease in the overall proportion of tests conducted in low-risk populations. When compared to the heterosexual-NIR category, PPV was significantly higher for men who have sex with men - people who use injection drugs (MSM-PWID) (52.7% compared to 100%, P < .001), MSM (52.7% compared to 95.4%, P < .001), HIV-endemic (52.7% compared to 91.5%, P < .001), heterosexual - partner with identified risk (heterosexual-PIR) (52.7% compared to 77.3%, P = .042), and people who use injection drugs (PWID) (52.7% compared to 81.3%, P = 0.007). A total of 13.5% of reactive POC results did not have a serological sample submitted. CONCLUSIONS: Targeted testing towards populations at higher risk of HIV improved the overall test performance characteristics of Ontario's POC testing program. While not unexpected, the large discrepancies between PPV in higher-risk, compared to lower-risk populations, suggests the need for greater awareness and messaging of the likelihood of false positive test results in different populations.
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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 | 0.001 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".