Valutazione di convenienza economica comparata tra quietapina e risperidone nel trattamento della schizofrenia

Objective: To assess and compare the incremental healthcare resource consumption by schizophrenic patients because of Extra Pyramidal Symptoms (EPS) during treatment with two new antipsychotics: quetiapine and risperidone. Design: Cost analysis was performed through a decision tree. Time horizon was one year and the National Health System (NHS) perspective was assumed. A multiple regression model was set up to investigate the incremental healthcare resource consumption because of EPS. Costs for psychiatric interventions were derived from the records of ten community psychiatric services, while inpatient costs were calculated from literature records. NHS charges and market values were used for valuing tests and drug consumption, respectively. Main outcome measures and results: The use of quetiapine saved more than Lit 1,400,000 per patient in one-year period. From the sensitivity analysis it emerged, however, that final results are sensitive to changes in EPS incidence rate: quetiapine remains cost-saving compared with risperidone only if the EPS incidence rate with quetiapine is lower than 5.2% and the EPS incidence rate with risperidone is equal or higher than 9.74%. Conclusions: Based on the hypothesis that the two drugs are therapeutically equivalent in the treatment of schizophrenia, quetiapine is economically advantageous compared with risperidone. However, direct comparisons of the two drugs in clinical trials and longitudinal studies are needed to confirm this hypothesis.