PGI21 COST PER ACCEPTABLE LIFE-YEARS AND COST PER QALY GAINS IN NON-ACCEPTABLE HEALTH STATE FOR BIOLOGICAL TREATMENT IN CROHN'S DISEASE, A NOVEL APPROACH IN HEALTH ECONOMIC MODELLING

Abstract

In resource-constrained settings there is growing interest in incorporating societal preferences about age and disease severity in health economic evaluations versus treating all QALY gains equally. Based on the finding that people consider certain health problems acceptable as normal part of ageing, the role of acceptable health states in health priority setting has recently been explored. According to sufficientarian reasoning, it may be sufficient (albeit morally important) to finance treatments from public resources until individuals reach acceptable health for their age. We aimed to explore two novel value functions using acceptability weights in health economic evaluation: 1) Acceptable Life Years (ALY) and 2) QALY gains in non-acceptable health (nQALY) We adapted a previously published cost-utility model comparing biological therapy sequences (infliximab biosimilar->adalimumab->vedolizumab versus infliximab biosimilar->adalimumab->standard care) in moderate to severely active luminal Crohn’s disease. In a pilot study, for each EQ-5D-3L index value we determined the percentage of people who consider them acceptable in different ages. Using the model health state utilities, ALYs were calculated by attaching a utility weight of 1 to the proportion of cohort in acceptable health state and 0 otherwise. nQALYs were calculated by subtracting QALY gains above the acceptability threshold from total QALY gains. We run the model on a horizon of 20 years, for patient cohorts from 18 to 100 years old, and compared the QALY, ALY and nQALY gains per unit resource use. When comparing 3rd line vedolizumab vs standard care, ALY gain was smallest for 18-year-olds and reached its maximum in the 78-year-old cohort. nQALY and QALY gains was similar until 60 years of age, when nQALY gain started rapid decline compared to QALY gain, reaching greatest difference in the 80-year-old cohort. We demonstrated that it is possible to adapt QALY-based cost-utility models to incorporate acceptability-based outcomes.