Metabolic effects and cost-effectiveness of aripiprazole versus olanzapine in schizophrenia and bipolar disorder

Objective: To assess the cost-effectiveness of aripiprazole versus olanzapine in the treatment of patients with schizophrenia or bipolar disorder in Sweden with focus on the metabolic impact of the treatments. Method: A Markov health-state transition model was developed. The risks of developing metabolic syndrome after one year of treatment with aripiprazole or olanzapine were derived from a pooled analysis of three randomised clinical trials. The subsequent risks of developing diabetes or coronary heart disease were based on previously published risk models. A societal perspective was applied, adopting a lifetime horizon. Univariate and probabilistic sensitivity analyses were conducted. Results: Treatment with aripiprazole dominates over olanzapine in both schizophrenia and bipolar disorder. In schizophrenia, quality-adjusted life-years (QALYs) gained were 0.08 and cost savings Swedish kronor (SEK) 30 570 (USD 4000); in bipolar disorder, QALYs gained were 0.09 and cost savings SEK 28 450 (USD 3720). In probabilistic sensitivity analyses, aripiprazole resulted in a dominant outcome in 84% of cases in schizophrenia and in 77% of cases in bipolar syndrome. Conclusion: The significantly lower risk of developing metabolic syndrome observed with aripiprazole compared with olanzapine is associated with less risk of diabetes and cardiovascular morbidity and mortality that translates into lower overall treatment cost and improved quality of life over time.