Evaluating the cost-effectiveness of rabies post-exposure prophylaxis: a case study in Tanzania

Abstract

Although fatal if untreated, human rabies can be prevented through post-exposure prophylaxis (PEP), which involves a course of vaccination and immunoglobulin administered immediately after exposure. However, high costs and frequent lack of rabies vaccine and immunoglobulin lead to about 55,000 deaths per year worldwide. Using data from a detailed study of rabies in Tanzania, we calculate a cost-effectiveness ratio for PEP when the WHO-recommended Essen regimen, a 5-dose intramuscular vaccination schedule, is adopted. Our analyses indicate a cost-effectiveness ratio for PEP of $27/quality-adjusted life year (QALY) from a health care perspective and $32/QALY from a societal perspective in Tanzania. From both perspectives, it is "very cost-effective" to administer PEP to patients bitten by an animal suspected to be rabid. Moreover, PEP remains "very cost-effective" provided that at least 1% of doses are administered to people who were actually exposed to rabies.

Fig. 1

Age distribution of suspected rabid-animal-bite victims and data fitting using a gamma distribution.

Fig. 2

Decision tree for determining cost-effectiveness of post-exposure prophylaxis (PEP) following the bite of a suspect rabid dog for preventing human rabies deaths. We define P1, P2 and P3 as the probability of receiving PEP, the probability that the suspected animal is rabid, and the probability of developing rabies based on the site of the bite, respectively (see Table 1 for parameter/probability estimates).

Fig. 3

Cost-effectiveness ratios for rabies post-exposure prophylaxis using intramuscular administration of vaccine for various ages of infections from health care and societal perspectives. QALY: quality-adjusted life year.

Fig. 4

Age distribution of a cost-effectiveness ratio for rabies post-exposure prophylaxis using intramuscular administration of vaccine (a) from a health care perspective and (b) from a societal perspective. QALY: quality-adjusted life year.

Fig. 5

Cost-effectiveness ratios for rabies post-exposure prophylaxis using intramuscular administration of vaccine from health care and societal perspectives, as P2 (the rabies recognition probability) is varied. QALY: quality-adjusted life year.

Fig. 6

Cost-effectiveness ratios for rabies post-exposure prophylaxis using intramuscular administration of vaccine from health care and societal perspectives, at a range of costs per dose. QALY: quality-adjusted life year.