Quetiapine: a pharmacoeconomic review of its use in bipolar disorder.

This article briefly summarizes the burden of bipolar disorder and the clinical profile of quetiapine (Seroquel®) in the management of bipolar disorder, followed by a detailed review of pharmacoeconomic analyses. Quetiapine is an atypical antipsychotic that is available in numerous countries as immediate-release and extended-release tablets for the treatment of major psychiatric disorders, including bipolar disorder. Randomized, double-blind, placebo-controlled trials with quetiapine have demonstrated its efficacy in bipolar I and II disorders, and the drug has been generally well tolerated in clinical trials. Three cost-effectiveness analyses of maintenance therapy in bipolar I disorder, which used similar Markov models and incorporated data from key clinical trials and a number of other sources, showed that quetiapine, as adjunctive therapy with mood stabilizers (lithium or divalproex), was a cost-effective treatment option from the healthcare payer perspective in the UK and the US. Quetiapine either dominated comparators (typically mood stabilizers alone) or was associated with incremental cost-effectiveness ratios that were usually well below widely accepted thresholds of cost effectiveness. One of the studies evaluated extended-release quetiapine, although clinical efficacy data used in the Markov model were for the immediate-release formulation. In another analysis, which used a discrete-event simulation model and was conducted from the perspective of the UK healthcare payer, quetiapine monotherapy was cost effective compared with olanzapine monotherapy as maintenance treatment for all phases of bipolar I or II disorder. In this model, favourable results were also shown for quetiapine (with or without mood stabilizers) compared with a wide range of maintenance therapy regimens. Another modelled analysis conducted from the UK healthcare payer perspective showed that quetiapine was dominated by haloperidol in the short-term treatment of a manic episode in patients with bipolar I disorder. Both favourable and unfavourable results have been reported in cost analyses of quetiapine in bipolar disorder (type I or type not specified). Possible explanations for some of the variability in results of the pharmacoeconomic analyses include heterogeneity among the models in terms of input parameters or assumptions in the base-case analyses, country- or region-specific differences in estimates of healthcare resource use and associated costs, variability in treatment alternatives, and differences in the year of costing and discounting used in the analyses. In addition, some of the studies had short time horizons and focused on acute manic episodes only, whereas others were longer-term analyses that considered the full spectrum of health states in patients with bipolar disorder. Various limitations of the studies have been recognized, and results from one country may not be applicable to other countries. In conclusion, results of available pharmacoeconomic analyses provide evidence of the cost effectiveness of quetiapine as an adjunct to mood stabilizers for maintenance therapy in (primarily type I) bipolar disorder from a healthcare payer perspective in the UK and the US. Some evidence is available to support the cost effectiveness of quetiapine monotherapy or the use of extended-release quetiapine as adjunctive therapy with mood stabilizers in this setting, although further analyses appear to be warranted. Whether these findings apply to other geographical regions requires further study. Evidence for the long-term (>2-year) cost effectiveness of quetiapine in bipolar disorder is currently limited and further studies are also needed to address the cost effectiveness of quetiapine from a societal perspective and in bipolar II disorder.