O12.4 Impact and cost-effectiveness of hiv prevention interventions among transgender women sex-workers in lima, peru using mathematical modelling informed by stakeholder analysis and health system capacity evaluation

Background HIV incidence remains high among transgender women (TW) in Lima, of whom the majority report sex-work. A stakeholder analysis and a health-system capacity assessment informed a mathematical modelling study to devise a tailored combination prevention programme. We modelled impact and cost-effectiveness of realistic combinations of interventions among TW sex-workers (TW-SW) in Lima. Methods In an HIV policy dialogue, a stakeholder analysis provided data on acceptability, feasibility, appropriate coverage targets and scale-up times of both novel and (improved) existing interventions. The health system study assessed capacity, costs and needs. Using a published model we simulated HIV transmission among TW-SW, their clients and stable partners, with implementation of combinations of the following interventions: 15% and 10% relative increase in condom use with clients and stable partners respectively, 15% pre-exposure prophylaxis (PrEP) coverage, treatment following new WHO guidelines and “test and offer”, both including testing promotion and leading to 65 and 75% coverage respectively. A social/structural component was part of all scenarios. The interventions’ individual and combined impact and cost-effectiveness were assessed. Results Combining increased condom use with clients and treatment under new WHO guidelines resulted in around 50% of new infections averted over 10 years; this was highly cost-effective ($90/DALY averted), under the World Bank threshold though feasibility of condom use increases remains problematic. Treatment in isolation was over the highly cost-effective threshold. A15% coverage of PrEP might be feasible and adds to impact, but is not cost-effective at $1440/year. Conclusions Implementing WHO treatment guidelines, combined with increased condom use among TW-SW would be highly effective and cost-effective. Inclusion of PrEP adds to impact but requires drastic cost reductions to become cost-effective. Success of all interventions is contingent on effective adherence support. Involving stakeholders in the elaboration of mathematical modelling studies is feasible, and should result in more relevant cost-effectiveness analyses to support programmatic decision-making. Declaration of conflicts of interest Dr. Guanira was the principal investigator for the Peruvian IPrEX sites. All authors declare having no conflicts of interest.