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.