Pharmacoeconomics of depot antipsychotics for treating chronic schizophrenia in Sweden.

AIMS: To determine the cost-effectiveness of long-acting injectable (LAI) antipsychotics for chronic schizophrenia in Sweden.

METHODS: A 1-year decision tree was developed for Sweden using published data and expert opinion. Five treatment strategies lasting 1 year were compared: paliperidone palmitate (PP-LAI), olanzapine pamoate (OLZ-LAI), risperidone (RIS-LAI), haloperidol decanoate (HAL-LAI) and olanzapine tablets (oral-OLZ). Patients intolerant/failing drugs switched to another depot; subsequent failures received clozapine. Resources and employment time lost (indirect costs) were costed in 2011 Swedish kroner (SEK), from standard government lists. The model calculated the average cost/patient and quality-adjusted life-years (QALYs), which were combined into incremental cost-effectiveness ratios. Multivariate and 1-way sensitivity analyses tested model stability.

RESULTS: PP-LAI followed by OLZ-LAI had the lowest cost/patient (189,696 SEK) and highest QALYs (0.817), dominating in the base case. OLZ-LAI followed by PP-LAI cost 229,775 SEK (0.812 QALY), RIS-LAI followed by HAL-LAI cost 221,062 SEK (0.804 QALY), HAL-LAI followed by oral-OLZ cost 243,411 SEK (0.776 QALY), and oral-OLZ followed by HAL-LAI cost 249,422 SEK (0.773 QALY). The greatest proportions of costs (52.5-83.8%) were for institutional care; indirect costs were minor (2.4-3.8%). RESULTS were sensitive to adherence and hospitalization rates, but not drug cost. PP-LAI followed by OLZ-LAI dominated OLZ-LAI followed by PP-LAI in 59.4% of simulations, RIS-LAI followed by HAL-LAI in 65.8%, HAL-LAI followed by oral-OLZ in 94.0% and oral-OLZ followed by HAL-LAI in 95.9%; PP-LAI followed by OLZ-LAI was dominated in 1.1% of the 40,000 iterations.

CONCLUSION: PP-LAI followed by OLZ-LAI was cost-effective in Sweden for chronic schizophrenia and cost-saving overall to the healthcare system.