Cost-effectiveness of pneumococcal vaccination strategies in older adults of Hong Kong

Abstract

OBJECTIVES : Older age is a risk factor for pneumococcal diseases and vaccination is effective in disease prevention. In Hong Kong, two pneumococcal vaccines are available for older adults but the choice of vaccine is challenging given the undefined cost-effectiveness in local landscape. We aimed to assess the cost-effectiveness of 13-valent pneumococcal conjugate vaccine (PCV13) versus 23-valent pneumococcal polysaccharide vaccine (PPSV23) in older adults of Hong Kong. METHODS : A deterministic cohort model was applied to compare the health and economic outcomes from a societal perspective. Population-specific model inputs, including incidence, mortality, case-fatality, vaccine-preventable serotype, risk group distribution, direct and indirect costs, were estimated from a Hong Kong-wide electronic medical database. Costs and health outcomes were discounted at 4% per year throughout the lifetime simulation. Vaccination strategies with an incremental cost-effectiveness ratio [ICER, defined as incremental cost per quality-adjusted life year (QALY) saved] less than one local GDP per capita ($42,432 in 2016) were considered as cost-effective. RESULTS : Compared with PPSV23, a single dose of PCV13 was projected to save $16 and 0.0044 QALYs for individuals, resulting $18.0 million healthcare expenditure saved at a population level. PCV13 was associated with negative value of incremental cost, positive value of incremental QALYs, negative value of ICER - indicating PCV13 is cost-saving in comparison with PPSV23. In the one-way sensitivity analysis (SA), the base-case results were robust to most of the parameter-uncertainties (25-125% of baseline value) but were sensitive to the efficacy of PCV13 in preventing inpatient pneumonia, and the incidence, case fatality, and medical costs of inpatient pneumonia. In probabilistic SA, PCV13 was cost-saving in 98% of the simulations. CONCLUSIONS : Compared with a single dose of PPSV23, a single dose of PCV13 was cost-saving for older adults in Hong Kong. Future immunization policies should consider the vaccine-preventable disease burden and the vaccine cost-effectiveness in such high-risk population.