Integrating Alternative Social Value Judgments Into Cost-Effectiveness Analysis of Vaccines: An Application to Varicella-Zoster Virus Vaccination.

OBJECTIVES: Cost-effectiveness analyses (CEA) are based on the value judgment that health outcomes (eg, quantified in quality-adjusted life-years; QALYs) are all equally valuable irrespective of their context. Whereas most published CEAs perform extensive sensitivity analysis on various parameters and assumptions, only rarely is the influence of the QALY-equivalence assumption on cost-effectiveness results investigated. We illustrate how the integration of alternative social value judgments in CEA can be a useful form of sensitivity analysis. METHODS: Because varicella-zoster virus (VZV) vaccination affects 2 distinct diseases (varicella zoster and herpes zoster) and likely redistributes infections across different age groups, the program has an important equity dimension. We used a cost-effectiveness model and disentangled the share of direct protection and herd immunity within the total projected QALYs resulting from a 50-year childhood VZV program in the UK. We use the UK population's preferences for QALYs in the vaccine context to revalue QALYs accordingly. RESULTS: Revaluing different types of QALYs for different age groups in line with public preferences leads to a 98% change in the projected net impact of the program. The QALYs gained among children through direct varicella protection become more important, whereas the QALYs lost indirectly through zoster in adults diminish in value. Weighting of vaccine-related side effects made a large difference. CONCLUSIONS: Our study shows that a sensitivity analysis in which alternative social value judgments about the value of health outcomes are integrated into CEA of vaccines is relatively straightforward and provides important additional information for decision makers to interpret cost-effectiveness results.

Reduced economic burden of AIDS-defining illnesses associated with adherence to antiretroviral therapy.

OBJECTIVES: We assessed the economic burden of AIDS-defining illnesses (ADIs), which was further stratified by adherence to antiretroviral therapy (ART). METHODS AND MATERIALS: A nationwide longitudinal cohort of 18,234 incident cases with HIV followed for 11years was utilized. Adherence to ART was measured by medication possession ratio (MPR). Generalized estimating equations modeling was used to estimate the cost impact of ADIs. RESULTS: Having opportunistic infections increased the annual cost by 9% (varicella-zoster virus infection) to 98% (cytomegalovirus disease), while the annual costs increased by 26% (Kaposi's sarcoma) to 95% (non-Hodgkin's lymphoma) in the year when AIDS-related cancer occurred. ADIs occurred more frequently in the years with low adherence for ART compared to the high-adherence years (e.g., 0.1≤MPR<0.8 vs. MPR≥0.8, event rate of cytomegalovirus disease 4.03% vs. 0.51%). The annual baseline costs in the years with MPR<0.1, 0.1≤MPR<0.8, and MPR≥0.8 were $250, $4,752, and $8,990 (in 2018 USD), respectively. The economic impact of ADIs in the years with low adherence (MPR<0.1) was larger than that in the high-adherence years (MPR≥0.8) (e.g., MPR<0.1 vs. MPR≥0.8, annual cost increased by 244% vs. 9% when candidiasis occurred). CONCLUSIONS: Adherence to ART may increase the baseline medical costs but mitigate the incidence and economic burden of ADIs.