Program Schedule

Optimizing HIV Pre-Exposure Prophylaxis Implementation among Men Who Have Sex with Men in Toronto: A Dynamic Modelling Study

Session: Poster Abstract Session: HIV Prevention Strategies
Saturday, October 11, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
Background: Once daily tenofovir/emtricitabine-based pre-exposure prophylaxis (PrEP) can reduce HIV acquisition in men-who-have-sex-with-men (MSM). To inform large-scale PrEP implementation, we examined the potential population-level impact and cost-effectiveness of different PrEP implementation strategies. 

Methods: We developed a dynamic, stochastic compartmental model of HIV transmission among the ~57,000 MSM in Toronto, Canada, stratified by HIV infection (CD4), serostatus (known/unknown diagnosis), and sexual behaviour. Parameterization was performed using local epidemiologic data. We calibrated the model to observed data on annual HIV diagnoses (300-400), annual HIV-attributable deaths (40-65), and ART coverage among MSM (50-70%). Baseline annual HIV testing was 22%. Strategies examined included: a) uniform PrEP delivery vs. targeting the highest-risk decile of MSM (avg. 36 partners/year); b) varying PrEP efficacy (44% to 99%); c) increasing HIV test frequency (Q3 to Q24 months). Outcomes included HIV infections averted and the incremental cost (in $CAD) per incremental quality-adjusted-life-years (QALYs) gained over 10 years.

Results: Use of PrEP among all HIV-uninfected MSM at 25, 50, 75, and 100% coverage prevented 832, 1387, 1693, and 1736 infections respectively, with costs per QALY increasing from $230,000 to $300,000. Targeted PrEP for the highest-risk MSM at 25, 50 75, and 100% coverage prevented 241, 452, 555, and 590 infections respectively, with costs per QALY ranging from $45,000-60,000 CAD. Maximizing PrEP efficacy prevented 424 infections with a cost per QALY of $32,000 (assuming PrEP in 25% of high-risk). HIV testing alone (Q3 months) averted 50% of infections with a cost per QALY of less than $10,000. However, increasing HIV testing frequency had minimal prevention impact. Maximizing PrEP efficacy increased the number of infections prevented. Assuming PrEP use in 25% of high-risk MSM with 99% efficacy and with Q3 month testing, a $32,000 cost per QALY was achieved.

Conclusion: Among those examined, the optimal implementation strategy for PrEP over the next 10 years in Toronto is to target high-risk MSM with strategies to maximize efficacy. Frequent HIV testing alone in high-risk individuals provides a substantial benefit.

Derek Macfadden, MD, Infectious Diseases, University of Toronto, Toronto, ON, Canada, Darrell Tan, MD, Infectious Diseases, St Michaels Hospital, Toronto, ON, Canada and Sharmistha Mishra, MD, Imperial College, London, United Kingdom


D. Macfadden, None

D. Tan, None

S. Mishra, None

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