A systematic review and economic model of the clinical effectiveness and cost-effectiveness of interventions for preventing relapse in people with bipolar disorder

Abstract

To determine the clinical effectiveness and cost-effectiveness of pharmacological and/or psychosocial interventions for the prevention of relapse in people with bipolar disorder. Major electronic databases were searched up to September 2005. Systematic reviews were undertaken on the clinical and economic effectiveness of treatments. An analysis was performed using the methods of mixed treatment comparison (MTC) to enable indirect comparisons to be made between the treatments. An economic model of treatments for the prevention of relapse in bipolar disorder was developed. Forty-five trials were included in the clinical effectiveness review; all but one studied adults. This review found that for the prevention of all relapses, lithium, valproate, lamotrigine and olanzapine performed better than placebo, with lithium and lamotrigine having the strongest evidence. For depressive relapse prevention, valproate, lamotrigine and imipramine performed better than placebo, with evidence strongest for lamotrigine and weakest for imipramine. For manic relapses, lithium and olanzapine performed significantly better than placebo. The MTC found that the best treatment for bipolar I patients with mainly depressive symptoms was valproate, followed by lithium plus imipramine. For bipolar I patients with mainly manic symptoms, olanzapine was the best treatment. From the studies investigating psychosocial interventions, there were few data for each comparison and outcome. The evidence suggests that cognitive behaviour therapy (CBT), in combination with usual treatment, is effective for the prevention of relapse. Group psychoeducation and possibly family therapy may also have roles as adjunctive therapy for preventing relapse. The results from the decision analytic model developed on the cost-effectiveness of long-term maintenance treatments of bipolar I patients suggest that the choice of treatment is dependent upon a number of factors: the previous episode history of a patient and the mortality benefit assumed for lithium strategies. The results from the base-case analysis for patients with a recent history of depression suggest that valproate, lithium and the combination of lithium and imipramine are potentially cost-effective depending upon the amount that a decision-maker is willing to pay for additional health gain. Using conventional amounts that the NHS is prepared to pay for health gain, then the lithium-based strategies appear to be potentially cost-effective for this group. For patients with a recent history of mania, the choice of pharmacological intervention appears to be between olanzapine and lithium monotherapy. Again using conventional threshold as a reference point, the results suggest that lithium is the most cost-effective therapy. Excluding the additional mortality benefit associated with lithium-based strategies resulted in all treatments for patients with a recent history of a depressive episode being dominated by valproate and, in the case of patients with a recent history of a manic episode, by olanzapine. Lithium, valproate, lamotrigine and olanzapine are effective as maintenance therapy for the prevention of relapse in bipolar disorder. Olanzapine and lithium are efficacious for the prevention of manic relapses and valproate, lamotrigine and imipramine for the prevention of depressive relapse. There is some evidence that CBT, group psychoeducation and family therapy might be beneficial as adjuncts to pharmacological maintenance treatments. Insufficient information is available regarding the relative tolerability of the treatments or their relative effects on suicide rate and mortality. For patients with a recent depressive episode, valproate, lithium monotherapy and the combination of lithium and imipramine are potentially cost-effective. For patients with a recent manic episode, olanzapine and lithium monotherapy are potentially cost-effective. The cost-effectiveness estimates in both groups of patients were shown to be sensitive to the assumption of a reduced suicidal risk associated with lithium-based strategies. Further research is needed into the adverse effects of all treatments and the differential effects of agents. Good-quality trials of valproate, of combination therapy, e.g. lithium plus a selective serotonin reuptake inhibitor antidepressant, of psychosocial interventions and of the disorder in children are also required.