Budget impact analysis of long acting injection for schizophrenia in Japan.

To estimate the budgetary impact of providing additional reimbursement for long acting injections for schizophrenia patients in psychiatric hospital settings in Japan to improve patient outcomes in schizophrenia. Budget impact analysis of change in reimbursement policy using a prevalence-based model over a five-year time horizon. The results are reported as net change in expenditure and consequent cost/savings in Japanese yen at the time of analysis. The budget impact analysis shows that an increase in reimbursement for LAIs could lead to cumulative savings of an estimated 36.6 billion JPY over five years. These savings result from a decrease in hospitalization costs and an increased usage of LAI (assumed to be 10%). Based on the sensitivity analysis, the saving estimates are most sensitive to change in market share of generic and branded oral antipsychotics. Historical data were used to estimate the future costs of drug and hospitalization; however, it is not the best predictor of future, hence a source of potential bias. A good level of treatment adherence with oral antipsychotics was assumed, which is generally not the case; therefore, we might have overestimated the effectiveness of oral atypical antipsychotics. Additionally, the drug cost due to reimbursement might have also been overestimated because in clinical setting, the increase of LAI use may not have reached 10% of the market share. Lastly, patients' behavior was derived from models, which may have loosely approximated the reality. An additional reimbursement for the use of LAI in schizophrenia patients is likely to be cost neutral/cost saving and should be considered as a policy option to improve patient outcomes and budget sustainability.