[Comparison of medical and economic benefits of antipsychotics in the treatment of schizophrenia in France].

INTRODUCTION: The course of schizophrenia can vary widely, and patients experience remission phases alternating with relapse episodes, which generally lead to hospitalisation and have a significant impact on the burden of disease. The prevalence of schizophrenia in France is estimated to be approximately 600,000 people, with an incidence of 10,000 new patients per year. Patients with schizophrenia represent the largest group of hospitalised patients in French public institutions and specialised centres, and the French authorities recognise that the management of schizophrenia is a major public health concern. The Haute Autorité de Santé (HAS) and most of the evidence-based guidelines for the maintenance treatment of schizophrenia recommend long-acting injectable (LAI) antipsychotics to be used predominantly in the prevention of relapse for non-compliant patients; however, in clinical practice, the use of LAIs remains low.

OBJECTIVE: This analysis aimed to estimate and to compare the cost-effectiveness of the most common antipsychotic strategies in France in the management of schizophrenia.

METHODS: A Markov model was developed to simulate the progression of a cohort of patients with schizophrenia through four health states (stable treated, stable non-treated, relapse and death) and considered up to three lines of treatment to account for changes in treatment management. Antipsychotics including aripiprazole LAI (ALAI), olanzapine LAI (OLAI), paliperidone LAI (PLAI), risperidone LAI (RLAI), haloperidol decanoate (HD) and oral olanzapine (OO) were compared in terms of costs and clinical outcomes. Thus, costs, quality-adjusted life-years (QALYs) and number of relapses were assessed over five years based on three-month cycles from a French health insurance perspective with a discount rate of 4 %. Patients were considered to be stabilised after clinical decompensation and would enter the model at an initiation phase, followed by a prevention of relapse phase if successful. Data (e.g. relapse or discontinuation rates) for the initiation phase came from randomised clinical trials, whereas relapse rates in the prevention phase were derived from hospitalisation risks based on French real-life data in order to capture adherence effects. Safety and utility data were derived from international publications. Additionally costs were retrieved from French health insurance databases and publications. Robustness of results was assessed through deterministic and probabilistic sensitivity analyses.

RESULTS: First and second generations of LAIs were found to have similar costs over five years; i.e. approximately € 55,000, except for PLAI which was associated with a discounted cost of € 50,880. Oral antipsychotics were found to be less costly (i.e. OO cost € 50,379 after five years) but associated with a lower number of QALYs gained and relapse avoided. PLAI and RLAI were associated with the greatest number of QALYs gained; i.e. PLAI dominated ALAI, OLAI and HD and was associated with an incremental costs-effectiveness ratio (ICER) of € 2411 per QALY gained versus OO. Finally, PLAI and OLAI were associated with the lowest number of relapses; i.e. PLAI dominated RLAI, ALAI and HLAI and was associated with an ICER of € 1782 per avoided relapse compared to OO. OO and HD were found to have led to the highest number of relapses.

CONCLUSION: This analysis, to the best of our knowledge, is the first of its kind to assess the cost-effectiveness of antipsychotics based on French observational data. PLAI was associated with the highest probability of being the optimal treatment from the French health insurance perspective.