Cost analysis of the adverse reactions of bipolar disorder treatment with aripiprazole and olanzapine in Spain

Abstract

Objective. This study investigates the healthcare costs of adverse events (AE) associated with treatment of bipolar disorder with two atypical oral antipsychotics (AOA): aripiprazole (ARI) and olanzapine (OLA).

Methods. A cost analysis using a Markov model considering the following health states was performed: no existence of adverse events (NAE); extrapyramidal symptoms (EPS); weight gain (WG); and sexual dysfunction (SD). Transition probabilities amongst health states were estimated from meta-analyses of clinical trials and from a retrospective Spanish study. The healthcare costs associated to each health state were obtained from a published Spanish study. The minimum acquisition cost per mg of the mean daily dose for each AOA was used. This is considered to be a relevant efficiency criterion in Hospital Pharmacy Departments. The time horizon applied in the analysis was 12 months. A probabilistic sensitivity analysis was performed for all the variables involved in the analysis with Monte Carlo simulations. All costs were updated to 2013 costs using the Spanish Health System price index.

Results. In comparison with OLA, treatment with ARI generates annual average cost savings per patient of €289 (CI95% €271; €308). In the hypothetical scenario in which we assume that ARI may have a similar rate of sexual dysfunction as that of quetiapine (i.e. the lowest rate amongst AOAs), the additional cost per patient would be €323 (CI95% €330; €317).

Conclusion. The results of this analysis show that patients treated with aripiprazole demonstrate lower adverse events costs in comparison to olanzapine. This difference may generate significant cost savings in the Spanish health system in the treatment of patients affected by bipolar disorders. The robustness of the results was tested via a probabilistic analysis.