P.674 Initiation of three-monthly palmitate paliperidone long-acting formulation in French clinical practice: results from the OPTIMUS study

Schizophrenia entails a considerable humanistic and economic burden. Improved treatment continuity to antipsychotic therapy is paramount to reduce the risk of relapse. The novel three-monthly paliperidone palmitate treatment (PP3M) offers the longest dosing interval currently available in France. This study assesses its cost-effectiveness, versus the currently available one-monthly long-acting treatment (PP1M) in French schizophrenic patients.A Markov model with monthly cycles was developed and adapted. It encompassed [a] administration of PP3M or PP1M in first-line, [b] a period where the patient does not receive any active treatment, and [c] a follow-up treatment line consisting of a treatment mix reflecting French clinical practice. Relapse rates in first-line were based on a pivotal non-inferiority head-to-head trial, and treatment discontinuation rates were based on French real-world data. Accounting for differences in drug exposure, time-dependent monthly relapse rates were applied following discontinuation to first line. The impact of a less frequent injection schedule for PP3M in QoL was accounted for through the application of a utility differential. The collective perspective was adopted throughout a 5-year time horizon. Four percent discount rates were applied on costs and outcomes.PP3M was dominant when compared to PP1M, featuring an incremental QALY of 0.123 and a cost saving effect (−669 €) resulting from reduced therapy costs (drug acquisition, administration and monitoring) and relapse-related costs. Sensitivity analysis supported the robustness of the results.With slightly better QALY outcomes and a cost-saving effect when compared to PP1M, introducing PP3M is an improvement to the current treatment in France.