Cost-effectiveness of rabies post-exposure prophylaxis in the context of very low rabies risk: A decision-tree model based on the experience of France

Introduction : Benefit-risk of different anti-rabies post-exposure prophylaxis (PEP) strategies after scratches or bites from dogs with unknown rabies status is unknown in very low rabies risk settings. Design and setting : A cost-effectiveness analysis in metropolitan France using a decision-tree model and input data from 2001 to 2011. Population : A cohort of 2807 patients, based on the mean annual number of patients exposed to category CII (minor scratches) or CIII (transdermal bite) dog attacks in metropolitan France between 2001 and 2011. Interventions : Five PEP strategies: (A) no PEP for CII and CIII; (B) vaccine only for CIII; (C) vaccine for CII and CIII; (D) vaccine+ rabies immunoglobulin (RIG) only for CIII; and (E) vaccine for CII and vaccine+ RIG for CIII. Main outcomes measures : The number of deaths related to rabies and to traffic accidents on the way to anti-rabies centers (ARC), effectiveness in terms of years of life gained by reducing rabies cases and avoiding traffic accidents, costs, and incremental cost-effectiveness ratios (ICER) associated with each strategy. Results : Strategy E led to the fewest rabies cases (3.6 × 10−8) and the highest costs (€1,606,000) but also to 1.7 × 10−3 lethal traffic accidents. Strategy A was associated with the most rabies cases (4.8 × 10−6), but the risk of traffic accidents and costs were null; therefore, strategy A was the most effective and the least costly. The sensitivity analysis showed that, when the probability that a given dog is rabid a given day (PA) was >1.4 × 10−6, strategy D was more effective than strategy A; strategy B became cost-effective (i.e. ICER vs strategy A <3 × French Gross Domestic Product per capita) when PA was > 1.4 × 10−4. Conclusions : In the metropolitan France's very low rabies prevalence context, PEP with rabies vaccine, administered alone or with RIG, is associated with significant and unnecessary costs and unfavourable benefit-risk ratios regardless to exposure category.