Figure 4. Breakeven effectiveness for PrEP as a function of its annual cost.

Effectiveness is measured as percentage reduction in chance of HIV infection acquisition. Assumes 25% of uninfected IDUs are enrolled in PrEP, in comparison to the status quo (no scale up of MMT or ART). Bottom line (triangles) shows minimum effectiveness for which PrEP would be considered highly cost effective (ICER = $7,400). Middle line (diamonds) shows minimum effectiveness for which PrEP would be as cost effective as MMT (ICER = $520). Top line (squares) shows minimum effectiveness for which PrEP would be cost saving (ICER = $0). PrEP = oral pre-exposure prophylaxis for injection drug users; ART = antiretroviral therapy; MMT = methadone maintenance therapy; ICER = incremental cost-effectiveness ratio.