Impact of extended-release quetiapine fumarate on hospitalization length and cost in schizophrenia and bipolar disorder patients: a retrospective, hospital-based, US-cohort analysis.

AIM: The aim was to evaluate the impact of quetiapine extended release (XR) on hospitalization length and cost in schizophrenia or bipolar disorder, versus quetiapine immediate release (IR), using Premier Perspective™ inpatient hospital database data. METHODS: Inpatient discharges classified within diagnosis-related group 430 (psychoses), prescribed quetiapine XR or IR, were identified. Patients had International Classification of Disease-9 diagnosis of schizophrenia or bipolar disorder. The impact of the XR formulation on hospitalization length and costs was assessed using generalized linear model analyses. RESULTS: A total of 30,429 discharges between 1 January 2008 and 30 June 2009 were analyzed. Patients who received quetiapine XR had significantly reduced hospitalization length (10.73% estimated reduction; p = 0.001) and cost (9.52% estimated reduction; p < 0.001), versus IR. This corresponds to a 1.0-day reduction in hospitalization (10.73% of 9.2 days) and US$532 reduction in hospitalization cost (9.52% of US$5588) per patient, based on least squares mean estimations. Evaluation of patient subpopulations suggested the reduction in length of hospitalization for quetiapine XR versus IR was driven mainly by patients with bipolar disorder, whereas cost reduction was driven mainly by patients with schizophrenia. CONCLUSION: Inpatient use of quetiapine XR in schizophrenia or bipolar disorder is associated with reduced hospitalization length and cost, possibly due to the faster titration schedule versus quetiapine IR.

Cost-effectiveness of second-generation antipsychotics for the treatment of schizophrenia.

OBJECTIVE: To compare the cost-effectiveness of alternate treatment strategies using second-generation antipsychotics (SGAs) for patients with schizophrenia. METHODS: We developed a Markov model to estimate the costs and quality-adjusted life-years (QALYs) for different sequences of treatments for 40-year-old patients with schizophrenia. We considered first-line treatment with one of the four SGAs: olanzapine (OLZ), risperidone (RSP), quetiapine (QTP), and ziprasidone (ZSD). Patients could switch to another of these antipsychotics as second-line therapy, and only clozapine (CLZ) was allowed as third-line treatment. We derived parameter estimates from the Clinical Antipsychotic Trial of Intervention Effectiveness (CATIE) study and published sources. RESULTS: The ZSD-QTP strategy (first-line treatment with ZSD, change to QTP if ZSD is discontinued, and switch to CLZ if QTP is discontinued) was most costly while yielding the greatest QALYs, with an incremental cost-effective ratio (ICER) of $542,500 per QALY gained compared with the ZSD-RSP strategy. However, the ZSD-RSP strategy had an ICER of $5,200/QALY gained versus the RSP-ZSD strategy and had the greatest probability of being cost-effective given a willingness-to-pay threshold between $50,000 and $100,000 per QALY. All other treatment strategies were more costly and less effective than another strategy or combination of other strategies. Results varied by different time horizons adopted. CONCLUSIONS: The ZSD-RSP strategy was most cost-effective at a willingness-to-pay threshold between $5,200 and $542,500 per QALY. Our results should be interpreted with caution because they are based largely on the CATIE trial with potentially limited generalizability to all patient populations and doses of SGAs used in practice.

Treatment patterns, healthcare resource utilization and costs in patients with bipolar disorder, newly treated with extended release or immediate release quetiapine fumarate using US healthcare administrative claims data.

BACKGROUND: Differences in treatment patterns, health care resource use, and costs are expected among patients newly treated with quetiapine extended release (XR) or quetiapine immediate release (IR). OBJECTIVE: To compare treatment patterns, health care resource use, and costs in patients with bipolar disorder newly treated with quetiapine XR or quetiapine IR. METHODS: This was an observational, retrospective cohort study that used HealthCore Integrated Research Database-identified patients (age range, 18-64 years) with an International Classification of Disease, Ninth Revision diagnosis of bipolar disorder and ≥1 pharmacy claim for quetiapine XR or quetiapine IR between October 2, 2008, and July 31, 2010. Outcomes were as follows: patient characteristics at the index date (first claim for quetiapine XR or quetiapine IR); 12-month preindex clinical characteristics, health care resource use, and costs; and 12-month postindex treatment patterns, health care resource use, and costs, assessed using generalized linear models (adjusted for index date and preindex patient demographic characteristics, clinical characteristics, health care resource use, and costs). RESULTS: In total, 3049 patients with bipolar disorder were analyzed (651 in the quetiapine XR group and 2398 in the quetiapine IR group). Of patients initiating treatment with quetiapine XR, 8.8% had no change in or discontinuation of their index therapy compared with 5.7% of patients treated with quetiapine IR (adjusted odds ratio, 1.44; 95% confidence interval, 1.03-2.00; P = 0.0317). The average daily dose (adjusted mean) of quetiapine XR was higher than quetiapine IR (225 vs 175 mg/d, P < 0.0001). An average daily dose of 300 to 800 mg was reached sooner (15.6 vs 30.8 days, P = 0.0049) and in more patients (44.2% vs 27.2%, P < 0.0001) who were taking quetiapine XR compared with patients taking quetiapine IR. No differences in total health care costs were found between the cohorts; however, patients taking quetiapine XR were less likely to be hospitalized for mental health-related reasons (12.1% vs 18.3%, P = 0.0022) and incurred lower mental health-related costs (US $6686 vs US $7577, P = 0.0063) compared with patients taking quetiapine IR. CONCLUSIONS: Treatment patterns and dosing differ in patients with bipolar disorder treated with quetiapine XR compared with those treated with quetiapine IR. Mental health-related hospitalizations and costs may be reduced in the 12 months after patients initiating treatment with quetiapine XR compared with initiating treatment with quetiapine IR.

Annual cost of relapses and relapse-related hospitalizations in adults with schizophrenia: results from a 12-month, double-blind, comparative study of lurasidone vs quetiapine extended-release.

PURPOSE: To model the economic impact of annual relapses/relapse-related hospitalizations among adults with schizophrenia treated with lurasidone or quetiapine extended-release (XR). METHODS: A probabilistic model estimating per-patient-per-year (PPPY) direct mental healthcare (MH) cost differences due to relapses/relapse-related hospitalizations was developed using relapse and relapse-related hospitalization rates from a 12-month, double-blind, parallel-group, global comparison study of lurasidone vs quetiapine XR (all patients previously treated with lurasidone or quetiapine XR for 6 weeks). Analyses were conducted for both all subjects and clinical responders. Direct costs associated with inpatient and outpatient mental healthcare-related services were obtained from a large, prospective, observational study of schizophrenia treatment in usual-care settings for relapsing and non-relapsing patients, including psychiatric hospitalizations, emergency services, medication management, and outpatient individual therapy. Model robustness was tested using univariate and probabilistic sensitivity analyses. RESULTS: Model-estimated PPPY MH cost savings associated with relapse-related hospitalization rates in all subjects were $3276 for lurasidone vs quetiapine XR. Lurasidone resulted in PPPY MH cost savings of $2702 vs quetiapine XR in all subjects, using relapse rates. Sensitivity analyses indicated lurasidone had lower 1-year MH costs than quetiapine XR in 100% and 99.7% of simulations, using relapse-related hospitalization rates and relapse rates, respectively, in all subjects. Similar results were seen in clinical responders. LIMITATIONS: The model represents a simplification of treatment patterns and response to treatment. Cost of treatment with lurasidone and quetiapine XR was not included in the model. Estimates of cost savings are likely conservative, as the model did not assess the impact of long-term cardiometabolic consequences. Indirect costs associated with relapses and non-mental health-related costs were also excluded from the model. CONCLUSION: Adults treated for schizophrenia with lurasidone are predicted to have lower 12-month MH costs compared to those treated with quetiapine XR due to fewer relapses and relapse-related hospitalizations.

Successful removal of quetiapine from a correctional formulary.

The abuse of medications in prison is a phenomenon well known among correctional health care professionals, and quetiapine has emerged as a drug of abuse in these settings. Considering the risks of abuse and diversion and the high cost compared with effective alternative antipsychotic medications, the New Jersey Department of Corrections (NJDOC) Pharmacy and Therapeutics Committee voted to remove quetiapine from the formulary. In a retrospective chart review, clinically relevant outcome measures were evaluated in patients prescribed quetiapine at the time of this change. Psychiatrists attempted to stop the quetiapine in 63.4 percent of the cases and were successful (not requiring continuation or restarting of the medicine) 95.7 percent of the time. There were no statistically significant differences in the number of patients who needed a higher level of care, days in a higher level of care, number of patients needing constant (e.g., suicide) watch, days on constant watch, suicidal behavior, or disciplinary charges when the subjects in whom an attempt to discontinue quetiapine was made was compared with those in whom it was continued. In 44.7 percent of cases in which an attempt was made to stop quetiapine (and in 28.3% of cases in the entire NJDOC population as of January 2009), no antipsychotic medication was needed to manage the patients during the study period. This study supports the decision to remove quetiapine from the NJDOC formulary.

Cost effectiveness of quetiapine in patients with acute bipolar depression and in maintenance treatment after an acute depressive episode.

BACKGROUND: Bipolar disorder has a significant impact upon a patient's quality of life, imposing a considerable economic burden on the individual, family members and society as a whole. Several medications are indicated for the acute treatment of mania and depression associated with bipolar disorder as well as for maintenance therapy; however, these have varying efficacy, tolerability and costs. OBJECTIVE: The objective of this study was to develop a new discrete-event simulation model to analyse the long-term consequences of pharmacological therapy for the management of bipolar I and II disorders (acute treatment of episodes of mania and depression as well as maintenance therapy). METHODS: Probabilities of remission and relapse were obtained from clinical trial data and meta-analyses. Costs (year 2011 values) were assessed from a UK healthcare payer's perspective, and included pharmacological therapy and resource use associated with the treatment of mood events and selected adverse events. The health effects were measured in terms of QALYs. RESULTS: For a patient starting with acute depression or in remission at 40 years of age (which was the average age in the clinical trials), quetiapine 300 mg/day was a cost-effective strategy compared with olanzapine 15 mg/day over a 5-year time frame. With acute bipolar depression as a starting episode, the 5-year medical costs were £323 higher and QALYs were 0.038 higher for quetiapine compared with olanzapine, corresponding to a cost-effectiveness ratio of £8600 per QALY gained. CONCLUSION: Compared with olanzapine, the results suggest that quetiapine is cost effective as a maintenance treatment for bipolar depression.

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.

Cost-effectiveness of adjunctive therapy with atypical antipsychotics for acute treatment of major depressive disorder.

BACKGROUND: While the clinical utility of atypical antipsychotics has been established in patients with major depressive disorder (MDD) who are refractory to antidepressant therapy, their cost-effectiveness is unknown. OBJECTIVE: To examine the cost-effectiveness of aripiprazole, quetiapine, and olanzapine/fluoxetine in adults with MDD who are refractory to antidepressant therapy. METHODS: Using techniques of decision analysis, we estimated expected outcomes and costs over 6 weeks in adults with MDD receiving (1) aripiprazole 2-20 mg/day and antidepressant therapy; (2) quetiapine 150 mg/day or 300 mg/day and antidepressant therapy; (3) the fixed-dose combination of olanzapine 6, 12, or 18 mg/day with fluoxetine 50 mg/day; or (4) antidepressant therapy alone. Cost-effectiveness was assessed in terms of the cost per additional responder at 6 weeks, defined as the ratio of the difference in the cost of MDD-related care over 6 weeks versus antidepressant therapy alone to the difference in the number of patients achieving clinical response by 6 weeks. We estimated the model using data from Phase 3 clinical trials of atypical antipsychotics along with other secondary data sources. RESULTS: With antidepressant therapy alone, the estimated clinical response rate at 6 weeks was 30%. Aripiprazole, quetiapine 150 mg/day, quetiapine 300 mg/day, and olanzapine/fluoxetine were estimated to increase clinical response at 6 weeks to 49%, 34%, 38%, and 45%, respectively. Costs of MDD-related care over 6 weeks were estimated to be $192 for antidepressant therapy, $847 for aripiprazole, $541 for quetiapine 150 mg/day, $672 for quetiapine 300 mg/day plus antidepressant therapy, and $791 for olanzapine/fluoxetine. Costs per additional responder (vs antidepressant therapy) over a 6-week period were estimated to be $3447 for aripiprazole, $8725 for quetiapine 150 mg/day, $6000 for quetiapine 300 mg/day, and $3993 for olanzapine/fluoxetine. CONCLUSIONS: Atypical antipsychotics substantially increase clinical response at 6 weeks. Cost per additional responder is lower for aripiprazole than for quetiapine or olanzapine/fluoxetine.

Cost-effectiveness of 12-month therapeutic assertive community treatment as part of integrated care versus standard care in patients with schizophrenia treated with quetiapine immediate release (ACCESS trial).

OBJECTIVE: To compare the 1-year cost-effectiveness of therapeutic assertive community treatment (ACT) with standard care in schizophrenia. ACT was specifically developed for patients with schizophrenia, delivered by psychosis experts highly trained in respective psychotherapies, and embedded into an integrated care system. METHOD: Two catchment areas in Hamburg, Germany, with similar population size and health care structures were assigned to offer 12-month ACT (n = 64) or standard care (n = 56) to 120 first- and multiple-episode patients with schizophrenia spectrum disorders (DSM-IV), the latter with a history of relapse due to medication nonadherence. Primary outcome was the incremental cost-effectiveness ratio (ICER) based on mental health care costs from a payer perspective and quality-adjusted life-years (QALYs) as a measure of health effects during the 12-month follow-up period (2006-2007). RESULTS: ACT was associated with significantly lower inpatient but higher outpatient costs than standard care, resulting in nonsignificantly lower total costs (P = .27). Incremental QALYs in the ACT group were 0.1 (P < .001). Thus, the point estimate for the ICER showed dominance of ACT. The probability of an ICER below €50,000 per QALY gained was 99.5%. CONCLUSIONS: The implementation of a psychotherapeutically oriented schizophrenia-specific and -experienced ACT team led to an improved patient outcome with reduced need of inpatient care. Despite the introduction of such a rather "costly" ACT team, treatment in ACT was cost-effective with regard to improved quality of life at comparable yearly costs. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01081418.

Intent-to-treat analysis of health care expenditures of patients treated with atypical antipsychotics as adjunctive therapy in depression.

OBJECTIVE: To compare health care utilization and expenditures in patients with depression whose initial antidepressant (AD) treatment was augmented with a second-generation antipsychotic. METHODS: Claims data from January 1, 2001, through June 30, 2009, were used to select patients aged 18 to 64 years with depression treated with ADs augmented with aripiprazole, olanzapine, or quetiapine. Patients were required to have 6 months of continuous eligibility before the first AD prescription and 6 months after the second-generation antipsychotic augmentation (index) date. Utilization and expenditures were assessed for 6 months after the index date. Multivariate regression was used to estimate adjusted expenditures and risks for hospitalizations and emergency department visits. RESULTS: A total of 483 patients treated with aripiprazole, 978 with olanzapine, and 2471 with quetiapine were selected. Mean adjusted expenditures for aripiprazole were significantly lower than those for olanzapine for each service category (all-cause, all-cause medical care, mental health-related, and mental health-related medical care) and were significantly lower than those for quetiapine for each category with the exception of mental health-related. The adjusted risks for hospitalization and emergency department visits were significantly higher for quetiapine than for aripiprazole. CONCLUSIONS: Compared with patients treated with ADs and aripiprazole, those treated with ADs and olanzapine or quetiapine had greater utilization and higher expenditures.

Cost effectiveness of adjunctive quetiapine fumarate extended-release tablets with mood stabilizers in the maintenance treatment of bipolar I disorder.

BACKGROUND: Bipolar I disorder (BPD I) is a recurrent illness that affects 1% of the US population and constitutes a large economic burden. However, few studies have investigated the cost effectiveness of maintenance treatment options for BPD I. OBJECTIVE: To determine the cost effectiveness of maintenance treatment with quetiapine fumarate extended-release (XR) tablets in combination with mood stabilizers (lithium or divalproex) in comparison with the following treatments: placebo in combination with lithium or divalproex; no maintenance treatment; lithium monotherapy; lamotrigine monotherapy; olanzapine monotherapy; and aripiprazole monotherapy. METHODS: The analysis was conducted from the societal and payer perspectives in the US, using a Markov model. The model simulated a cohort of 1000 stabilized BPD I patients and estimated the quarterly risk in three health states: euthymia, mania and depression. Efficacy data were derived from two randomized, double-blind trials comparing quetiapine + lithium/divalproex with placebo + lithium/divalproex for up to 2 years, as well as other published literature. Resource data were extracted from published literature. Drug costs, hospitalizations and physician visits were among the direct costs. Indirect costs included absenteeism, and mortality rates included suicide. Benefits and costs were discounted at 3% and the price reference year was 2009. Endpoints included number of acute mood episodes, hospitalizations due to an acute mood event and costs per QALY. Probabilistic sensitivity analysis (PSA) was conducted to evaluate uncertainty in the model inputs. RESULTS: Treatment with quetiapine XR + lithium/divalproex was associated with reductions in acute mania (46%), acute depression (41%) and related hospitalizations (44%) compared with placebo + lithium/divalproex, and similar reductions in events were observed relative to lithium monotherapy. In the base-case analysis from the payer perspective, the discounted incremental cost per QALY for quetiapine XR + lithium/divalproex compared with placebo + lithium/divalproex was $US22 959, and compared with lithium monotherapy was $US100 235, while all other comparators were dominated. PSA showed these results to be robust to select assumptions. CONCLUSIONS: Quetiapine XR + lithium/divalproex may be a cost-effective maintenance treatment option for patients with BPD I.

The management of individuals with bipolar disorder: a review of the evidence and its integration into clinical practice.

Bipolar disorder is a common, debilitating, chronic illness that emerges early in life and has serious consequences such as long-term unemployment and suicide. It confers considerable functional disability to the individual, their family and society as a whole and yet it is often undetected, misdiagnosed and treated poorly. In the past decade, many new treatment strategies have been trialled in the management of bipolar disorder with variable success. The emerging evidence, for pharmacological agents in particular, is promising but when considered alone does not directly translate to real-world clinical populations of bipolar disorder. Data from drug trials are largely based on findings that identify differences between groups determined in a time-limited manner, whereas clinical management concerns the treatment of individuals over the life-long course of the illness. Considering the findings in the context of the individual and their particular needs perhaps best bridges the gap between the evidence from research studies and their application in clinical practice. Specifically, only lithium and valproate have moderate or strong evidence for use across all three phases of bipolar disorder. Anticonvulsants, such as lamotrigine, have strong evidence in maintenance; whereas antipsychotics largely have strong evidence in acute mania, with the exception of quetiapine, which has strong evidence in bipolar depression. Maintenance data for antipsychotics is emerging but at present remains weak. Combinations have strong evidence in acute phases of illness but maintenance data is urgently needed. Conventional antidepressants only have weak evidence in bipolar depression and do not have a role in maintenance therapy. Therefore, this paper summarizes the efficacy data for treating bipolar disorder and also applies clinical considerations to these data when formulating recommendations for the management of bipolar disorder.

Cost-effectiveness of quetiapine with lithium or divalproex for maintenance treatment of bipolar I disorder.

BACKGROUND: Bipolar I disorder is a recurrent illness that affects 1% of the US population and constitutes a large economic burden. Few studies have investigated the cost-effectiveness of maintenance treatment options. The objective of this analysis was to assess the cost-effectiveness of quetiapine (QTP) in combination with lithium (Li) or divalproex (DVP) compared with that of Li or DVP alone for maintenance treatment of bipolar disorder. METHODS: The cost-effectiveness of maintenance treatment with QTP in combination with Li or DVP was compared with placebo (PBO) in combination with Li or DVP from a US direct costs perspective using a Markov model. The model simulated a cohort of 1,000 stabilized patients with bipolar I disorder and estimated the quarterly risk in three health states: euthymia, mania, and depression. Efficacy data were derived from two randomized, double-blind, placebo-controlled trials comparing QTP + Li/DVP with PBO + Li/DVP for up to 2 years. Resource data were obtained from published literature. Direct costs included drug costs, hospitalizations, and physician visits. Outcomes and costs were discounted at 3% and the price reference year was 2007. Endpoints included the number of acute mood episodes, hospitalizations due to an acute mood event, and costs per quality-adjusted life-years. A probabilistic sensitivity analysis (PSA) was conducted to evaluate uncertainty. RESULTS: In the base-case analysis, QTP + Li/DVP dominated PBO + Li/DVP. The PSA showed these results to be robust. In addition, treatment with QTP + Li/DVP was associated with reductions in acute manic episodes (46%), acute depressive episodes (41%), and related hospitalizations (44%) compared with PBO + Li/DVP. CONCLUSIONS: These analyses, based on two randomized clinical trials, suggest that QTP + Li/DVP is a cost-effective maintenance treatment option for patients with bipolar I disorder compared with Li or DVP alone.

Cost-effectiveness of quetiapine plus mood stabilizers compared with mood stabilizers alone in the maintenance therapy of bipolar I disorder: results of a Markov model analysis.

OBJECTIVE: The aim of this study was to estimate the following: (1) the number of acute mood events prevented by adjunctive quetiapine therapy, and the potential cost savings; (2) the number of acute mood event-associated hospitalizations avoided by using adjunctive quetiapine therapy, and the potential cost savings of this intervention; and (3) the economic value of adjunctive quetiapine therapy in the maintenance treatment of bipolar I disorder. METHODS: A Markov model was developed to simulate the transitions of newly stabilized adult patients with bipolar I disorder across 4 possible health states: euthymia, acute mania, acute depression, and discontinued/ no active therapy. Clinical data were obtained from 2 randomized, double-blind, Phase III trials of up to 2 years' duration (D1447C00126 and D1447C00127) that evaluated the efficacy and tolerability of quetiapine (versus placebo) when coadministered with lithium or valproate in increasing the time to recurrence of acute mood events in patients with bipolar I disorder. The model evaluated clinical and economic outcomes in 8 quarterly cycles (24 months). Outcome measures included the number of acute mood events, number of hospitalizations related to acute mood events, and their costs. Quality-adjusted life-years (QALYs) were calculated as a secondary outcome. The model was conducted from the perspective of the UK National Health Service, base year 2007. RESULTS: In the model analysis, adjunctive quetiapine with lithium or valproate was associated with a 54% reduction in the occurrence of acute mood events, a 29% reduction in acute mood event-related hospitalization costs, and a 4% improvement in QALY gains, with 5% lower total direct costs than placebo + lithium/valproate. The incremental cost-effectiveness ratios (in year-2007 pound) were 506 per additional acute mood event avoided, 4261 per additional acute mood event-related hospitalization prevented, and -7453 per additional QALY gained. The sensitivity analyses indicated that these results were robust. CONCLUSIONS: The results of this Markov model with a 2-year time horizon suggest that adjunctive quetiapine and mood-stabilizer therapy with lithium or valproate, compared with mood-stabilizer therapy alone in the maintenance treatment of patients with bipolar I disorder, were associated with fewer acute mood events, fewer acute mood event-related hospitalizations, and lower total costs, thereby improving patient mental health outcomes and minimizing impact on payer budgets, from the perspective of the UK National Health Service.