Clinical and economic impact of a combination Haemophilus influenzae and hepatitis B vaccine - Estimating cost-effectiveness using decision analysis

Background: Compliance with hepatitis B virus (HBV) vaccine remains subopti mal, despite a recommendation by the Advisory Committee on Immunization Pra ctices of the US Public Health Service that all newborns be vaccinated. Alt hough a combined HBV-Haemophilus influenzae type b (Hib) vaccine may improv e acceptance of the HBV vaccine, the clinical and economic consequences of this intervention are uncertain. Objectives: To compare the health impact and cost-effectiveness of the foll owing 2 immunization strategies: current practice of administering HBV vacc ine separately (75% compliance) and Hib vaccine alone or as part of a multi valent vaccine (95% compliance); and strategy of delivering a combined HBV- Hib vaccine (95% compliance). Design: A Markov model simulated the natural history of acute and chronic H BV and Hib disease in a cohort of US newborns. Clinical and economic variab les were obtained from published reports. Results: The Hib-related outcomes were the same in both strategies, because the efficacy and compliance with Hib vaccine were assumed to be equivalent in both. A 53% reduction in the number of cases of HBV infection with the combination strategy (n = 8541) was estimated when compared with current pr actice (n = 18 044), along with 205 fewer HBV-related deaths per 1 million infants. Immunization costs of the combination strategy were $11.5 million higher than for current practice ($108.4 million compared with $96.9 millio n), whereas the cost of HBV-related disease was $4.0 million lower than in current practice. The incremental cost-effectiveness ratio for the combinat ion strategy was $17 700 per year of life saved. Conclusion: An HBV-Hib vaccine in US infants yields substantial benefits, w ith a cost-effectiveness ratio that is lower than that of many commonly use d medical interventions.