Does the Choice of Health Metric, DALY or QALY, Influence Conclusions of Health Economic Evaluation? A Case Study of Rotavirus Vaccine in Burundi.

Abstract

Two metrics, quality-adjusted life-year (QALY) and disability-adjusted life-year (DALY), have been commonly used to measure health benefits associated with health interventions. This study aimed to explore the effect of the choice of health metric (DALY or QALY) on economic evaluation conclusion. A previous published model for a cost-utility analysis (CUA) of rotavirus vaccine was adapted to estimate the QALYs gained and DALYs averted from four rotavirus vaccines: Rotarix, RotaTeq, Rotavac, and Rotasiil. The study was conducted in both Burundi provider and societal perspectives over a five-year time horizon. Disability weights (DW) were derived from the Global Burden of Disease (GBD) study. Scenario analysis was performed to evaluate the impact of age weights and source of utility weight. In base-case analysis, the QALYs gained ranged from 46 to 78% of the DALYs averted. The incremental cost-effectiveness ratios (ICER) per QALY gained were higher than ICER per DALY averted by 28 to 113%, leading to less favorable cost effectiveness. The QALYs gained from using 1-DW as utility weight were slightly higher than those using EQ-5D utility weight obtained from previous literature, yet less likely to alter CUA conclusions. When age-weighting was incorporated in the DALY calculation, the ICERs per DALY averted were reduced leading to more favorable cost effectiveness. In case of rotavirus diarrhea, in which mortality burden is considered larger than morbidity due to short duration of disease, although the use of DALY consistently led to more favorable cost-effective result than the use of QALY such effects were considered small and less likely to affect the EE conclusion under current CET of 1 GDP per capita.