657. ECONOMIC EVALUATIONS OF EMERGING PHARMACOLOGICAL THERAPIES FOR TREATMENT RESISTANT DEPRESSION

Abstract Background Treatment resistant depression (TRD) affects approximately 30% of people with major depressive disorder (MDD) and is associated with significant individual and societal burden. Emerging pharmacological therapies (i.e.ketamine, esketamine, psilocybin) have evidence of efficacy in TRD; however, there is less data on their cost-effectiveness which is important for funding through governments and insurers. Without being subsidised, access to these treatments will likely be limited. Aims & Objectives Describe the essential components economic evaluation through the example of a within trial cost-utility analysis of racemic ketamine for TRD from health sector (primary) and societal perspectives. Method The cost-utility analysis alongside the KADS randomised controlled trial involved 179 participants receiving ketamine or midazolam (active control) for 4 weeks. Data on healthcare resource use, transportation, carer time and lost productivity were collected with self-reported questionnaires at baseline, post-treatment (4-weeks) and 8-weeks. Quality-adjusted life years (QALYs) were calculated using AQoL-8D utility values. Initial dosing was fixed (cohort 1) and changed to response-guided dosing (cohort 2). Base-case 1 included control arm treatment costs for cohort 2 participants. Base-case 2 excluded control arm treatment costs. Results After 4 weeks of randomised treatment, utility values were significantly higher for ketamine (0.435 vs. 0.352; p<0.05). In base-case 1, health sector incremental cost-effectiveness ratios (ICERs) were dominant (less costly and more effective) with probabilities of falling below $50,000/QALY of 89% (4-weeks) and 91% (8-weeks). Base-case 2 ICERs were $251,250/QALY (95% CI: $268,715 to $6,531,253) at 4-weeks and $108,500/QALY (95% CI $49,306 to $3,609,179) at 8-weeks with probabilities of falling below $50,000/QALY of 0% (4-weeks) and 2% (8-weeks). From a societal perspective, the probabilities of falling below $50,000/QALY were 30-32% (base-case 1) and 0-5% (base-case 2). Discussion & Conclusions The initial four-week treatment phase with racemic ketamine is cost-effective when control arm costs are included. At commonly used Australian cost-effectiveness thresholds, racemic ketamine would not be considered cost-effective when excluding control arm costs or from the societal perspective. Economic modelling is needed to estimate the longer-term cost-utility of this treatment.