Budgetary impact of treating acute bipolar mania in hospitalized patients with quetiapine: an economic analysis of clinical trials.

Objective: To present a tool that allows estimation of the budget impact of treatments for acute mania in bipolar I disorder from a US healthcare payer perspective.

Methods: Using discrete event simulation, the course of individuals is simulated beginning with hospitalization. Discharge depends on symptom level measured by the Young Mania Rating Scale (YMRS). The treatment effect is determined using time-dependent regression equations derived from trial data, and decision rules obtained from clinical experts. Outcomes include: time to response and symptom resolution; proportion of subjects reaching each outcome; number of adverse events. Costs were obtained from hospital discharge databases, the National Medicare Physician Fee Schedule and RedBook. Different scenarios are examined, each describing the proportion of subjects on the various treatments (lithium, divalproex sodium, olanzapine, risperidone, and quetiapine--monotherapy and in combination with lithium). Analyses are intention-to-treat over 100 days, corresponding to follow-up in mania trials. Despite its flexibility and structural adaptability, the model has some important limitations related to the characteristics of the clinical trials. These include focus on inpatient management of acute mania, use of the YMRS as the model driver, polypharmacy restricted to two-drug regimens, no explicit consideration of titration and dose changes, and relatively short time horizon.

Results: Scenarios with a greater proportion of quetiapine users (5% vs. 40% and 100%) result in a smaller impact on the healthcare budget (6912, 6277, and 5525 dollars per patient, respectively) and improvements in patient outcomes (e.g., 43%, 47%, and 54% responding at day 21; 74%, 77%, and 80% remitting by day 84). Sensitivity analyses showed that the budget impact is influenced by drug prices, discharge criteria and side-effect management.

Conclusion: Results suggest that increased use of quetiapine for bipolar mania in the US is economically justified and improves health outcomes. In addition, this model illustrates that discrete event simulation is a useful and versatile tool for budget impact analyses.