Background: Antipsychotic medication is the mainstay of treatment in schizophrenia. Long-acting medication has potential advantages over daily medication in improving compliance and thus reducing hospitalization and relapse rates. The high acquisition and administration costs of such formulations raise the need for pharmacoeconomic evaluation.
Objective: The aim of this article is to provide a comprehensive review of the available evidence on the cost effectiveness of long-acting/extended-release antipsychotic medication and critically appraise the strength of evidence reported in the studies from a methodological viewpoint.
Methods: Relevant studies were identified by searching five electronic databases: PsycINFO, MEDLINE, EMBASE, the NHS Economic Evaluation Database and the Health Technology Assessment database (HTA). Search terms included, but were not limited to, 'long-acting injection', 'economic evaluation', 'cost-effectiveness' and 'cost-utility'. No limits were applied for publication dates and language. Full economic evaluations on long-acting/extended-release antipsychotics were eligible for inclusion. Observational studies and clinical trials were also checked for cost-effectiveness information. Conference abstracts and poster presentations on the cost effectiveness of long-acting antipsychotics were excluded. Thirty-two percent of identified studies met the selection criteria. Pertinent abstracts were reviewed independently by two reviewers. Relevant studies underwent data extraction by one reviewer and were checked by a second, with any discrepancies being clarified during consensus meetings. Eligible studies were assessed for methodological quality using the quality checklist for economic studies recommended by the NICE guideline on interventions in the treatment and management of schizophrenia.
Results: After applying the selection criteria, the final sample consisted of 28 studies. The majority of studies demonstrated that risperidone long-acting injection, relative to oral or other long-acting injectable drugs, was associated with cost savings and additional clinical benefits and was the dominant strategy in terms of cost effectiveness. However, olanzapine in either oral or long-acting injectable formulation dominated risperidone long-acting injection in a Slovenian and a US study. Furthermore, in two UK studies, the use of long-acting risperidone increased the hospitalization days and overall healthcare costs, relative to other atypical or typical long-acting antipsychotics. Finally, paliperidone extended-release was the most cost-effective treatment compared with atypical oral or typical long-acting formulations. From a methodological viewpoint, most studies employed decision analytic models, presented results using average cost-effectiveness ratios and conducted comprehensive sensitivity analyses to test the robustness of the results.
Limitations: Variations in study methodologies restrict consistent and direct comparisons across countries. The exclusion of a large body of potentially relevant conference abstracts as well as some papers being unobtainable may have increased the likelihood of misrepresenting the overall cost effectiveness of long-acting antipsychotics. Finally, the review process was restricted to qualitative assessment rather than a quantitative synthesis of results, which could provide more robust conclusions.
Conclusions: Atypical long-acting (especially risperidone)/extended-release antipsychotic medication is likely to be a cost-effective, first-line strategy for managing schizophrenia, compared with long-acting haloperidol and other oral or depot formulations, irrespective of country-specific differences. However, inconsistencies in study methodologies and in the reporting of study findings suggest caution needs to be applied in interpreting these findings.