ECONOMIC EVALUATION OF LONG ACTING ANTIPSYCHOTIC INJECTION IN SCHIZOPHRENIA

Abstract

Long acting injection anti-psychotics (LAIs) are suggested in management of schizophrenia with oral medication non-adherence. Four of first generation LAIs; Haloperidol dec, Flupentixol dec, Flupenazine dec . and Zuclopentixol dec., are listed in national list of essential medicine except two of newer second generation LAIs.; Paliperidone LAI, and Risperidone LAI. Economic evaluation evidence of these medications may not only guide healthcare profession to choose LAIs for their patients appropriately but also support healthcare policy makers to consider any newer interventions for future health benefit scheme. This research aims to assess cost effectiveness of six LAIs registered in Thailand for schizophrenia with oral medication non-adherence. Method: A cohort Markov modelling for cost utility analysis of six LAIs is conducted under societal perspective. Model structure is modified from NICE economic model for schizophrenia. Three mutually exclusive outcomes include number of subjects with relapse, discontinuation with intolerable side effect, and due to other reasons are considered. The transitional probability of these outcomes are retrieved from systematic review and mixed treatment comparison meta-analysis with completing risk models. Bayesian framework is applied for meta-analysis work. Other published cost data accessed where available are adjusted to present values of the current analysis year 2014. Deterministic analysis and probabilistic sensitivity analysis are applied for two time horizons; 10 year and lifetime, and presented in the cost effective analysis plane and the cost effectiveness acceptability curve respectively. This economic evaluation will follow HITAP guideline. Markov economic modelling is conducted in TreeAgePro 2014 software. Result of the deterministic analysis, Haloperidol dec. is the most cost effective among 6 LAIs for first line treatment of schizophrenia with oral non-adherence. Flupenazine dec., Flupentixol dec. Paliperidone LAI and Risperidone LAI. might be next alternatives if Haloperidol dec is not available, with ICER of 808,580, 3,995,921, 5,052,900, and 32,712,811 baht per QALY gained. However these ICERs exceed the willingness to pay threshold. However, Zuclopentixol dec is not cost effective option because ICER is -627,116 baht/QALY. Probabilistic analysis also suggests Haloperidol dec has highest probability of being cost effective, with wide range of willingness to pay threshold, among the other LAIs for the first line treatment of schizophrenia with oral non-adherence. Higher probability of being more cost effective of Paliperidone LAI and Risperidone LAI than Haloperidol dec may be seen when WTP threshold increases up to 3,000,000 baht/QALY. Analysis results of both time horizons remain the same. In conclusion, Haloperidol dec is the most cost effective LAIs for the first line treatment in schizophrenia with oral non adherence under deterministic and probabilistic analysis. Future researches to address uncertainty of economic models may include long term neurological and metabolic side effects, utility of repeated relapses and variation of patient intrinsic factors.