Trends in Sexual Behavior and Sexually Transmitted Infections After Initiating Human Immunodeficiency Virus Pre-Exposure Prophylaxis in Men Who Have Sex with Men from Amsterdam, the Netherlands: A Longitudinal Exposure-Matched Study
Bibliographic record
Abstract
Men who have sex with men (MSM) initiating human immunodeficiency virus (HIV) pre-exposure prophylaxis (PrEP) may increase condomless anal sex (CAS) and number of partners, and, consequently, more often acquire sexually transmitted infections (STIs). Using data from the Amsterdam Cohort Studies, we compared sexual behavior and STI among MSM after PrEP-initiation with controls not initiating PrEP. The MSM reported on sexual behavior and were tested for HIV, chlamydia, gonorrhea, and syphilis semi-annually. We matched MSM who initiated PrEP between January 1, 2015 and December 31, 2019 1:1 to MSM who did not use time-dependent propensity scores based on age, sexual behavior, and STI. Primary end-points were number of casual partners, and proportion with CAS and receptive CAS (rCAS) with casual partners, sexualized drug use (SDU), any STI, and anal STI. We modeled end-points during the 4 years before and 2 years after PrEP-initiation or matched PrEP-initiation timepoint by using logistic regression (dichotomous end-points) or negative binomial regression (count end-point), adjusted for calendar year. Two hundred twenty-eight out of the 858 (26.6%) MSM initiated PrEP. We matched 198 out of 228 (86.8%) to a control. Before PrEP-initiation, end-points increased over time in both groups, with no statistically significant difference. The odds of CAS, rCAS, and anal STI were on average higher after than before PrEP-initiation in PrEP initiators, whereas after versus before differences were not observed in controls. After PrEP-initiation, PrEP initiators had statistically significantly more casual partners, and higher odds of CAS, rCAS, SDU, any STI, and anal STI than controls. These findings support frequent STI screening and counseling in MSM using PrEP.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".