An exploratory intersectional analysis of syphilis prevalence among people who inject drugs in Montreal, Canada
Bibliographic record
Abstract
ABSTARCT Background Syphilis notifications have increased among women and heterosexual men in Canada and people who inject drugs (PWID) are an emerging group at risk of infection. We examined syphilis prevalence among PWID and how this varied by intersecting population groups, socio-structural factors and sexual and substance use behaviors. Methods Data were from HEPCO, a cohort study of PWID in Montreal. We tested for syphilis via venipuncture with treponemal testing reflexed to non-treponemal testing if positive. We included the result at each person’s first test and exact logistic regression was used to examine differences in the prevalence of lifetime syphilis infection. Results Between November 2022 and March 2024, 386 people (16.1% women) had a syphilis test. Thirty-three people (8.6%) had lifetime syphilis and two people (0.5%) had active syphilis. Prevalence was significantly higher among men identifying as gay or bisexual, men with HIV, and those who reported recent sex work, condom-less sex, 2 or more sex partners and amphetamine injecting. Among women with syphilis, prevalence was higher among those who reported recent sex work, recent unstable housing and amphetamine injecting; however, the confidence interval included the null. Conclusion Active syphilis infection was uncommon among this cohort of PWID; however, lifetime syphilis infection was almost 9%. Among men in this cohort, there is evidence that syphilis intersects with other key population group characteristics. More data are needed to better understand syphilis among women who inject drugs. Periodic syphilis testing among PWID may be justified alongside testing for other sexually transmissible and blood borne infections. What is already known on this topic Contemporary increases in syphilis infection notifications in high income countries has been linked to substance use, including injecting drug use. However, there is a limited understanding of syphilis specifically among people who inject drugs. What this study adds This is the first study in more than 10 years to examine syphilis prevalence among people who inject drugs in Montreal, the second biggest city in Canada. Active syphilis was uncommon but still higher than the Canadian general population. Lifetime syphilis was associated with a range of intersecting key population groups and behaviours. How this study might affect research, practice or policy Our study provides a contemporary understanding of syphilis specifically among people who inject drugs in Montreal. Syphilis testing may be warranted among people who inject drugs to ensure prevalence stays low and guidelines from the Quebec government dating from 2019 should be revised.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.005 | 0.010 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.003 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".