Cost-effectiveness model of long-acting risperidone in schizophrenia in the US

Schizophrenia is a devastating and costly illness that affects 1% of the population in the US. Effective pharmacological therapies are available but suboptimal patient adherence to either acute or long-term therapeutic regimens reduces their effectiveness. The availability of a long-acting injection (LAI) formulation of risperidone may increase adherence and improve clinical and economic outcomes for people with schizophrenia.

To assess the cost effectiveness of risperidone LAI compared with oral risperidone, oral olanzapine and haloperidol decanoate LAI over a 1-year time period in outpatients with schizophrenia who had previously suffered a relapse requiring hospitalisation.

US healthcare system.

Published medical literature, unpublished data from clinical trials and a consumer health database, and a clinical expert panel were used to populate a decision-analysis model comparing the four treatment alternatives. The model captured: rates of patient compliance; rates, frequency and duration of relapse; incidence of adverse events (bodyweight gain and extrapyramidal effects); and healthcare resource utilisation and associated costs. Primary outcomes were: the proportion of patients with relapse; the frequency of relapse per patient; the number of relapse days per patient; and total direct medical cost per patient per year. Costs are in year 2002 US dollars.

Based on model projections, the proportions of patients experiencing a relapse requiring hospitalisation after 1 year of treatment were 66% for haloperidol decanoate LAI, 41% for oral risperidone and oral olanzapine and 26% for risperidone LAI, while the proportion of patients with a relapse not requiring hospitalisation were 60%, 37%, 37% and 24%, respectively. The mean number of days of relapse requiring hospitalisation per patient per year was 28 for haloperidol decanoate LAI, 18 for oral risperidone and oral olanzapine and 11 for risperidone LAI, while the mean number of days of relapse not requiring hospitalisation was 8, 5, 5 and 3, respectively. This would translate into direct medical cost savings with risperidone LAI compared with oral risperidone, oral olanzapine and haloperidol decanoate LAI of USD 397, USD 1742, and USD 8328, respectively. These findings were supported by sensitivity analyses.

The use of risperidone LAI for treatment of outpatients with schizophrenia is predicted in this model to result in better clinical outcomes and lower total healthcare costs over 1 year than its comparators, oral risperidone, oral olanzapine and haloperidol decanoate LAI. Risperidone LAI may therefore be a cost saving therapeutic option for outpatients with schizophrenia in the US healthcare setting.