According to this DES model for schizophrenia, atypical antipsychotics are cost-effective compared to the conventional antipsychotics. The assumptions used in the model need further validation through large naturalistic based studies with reasonable follow-up to determine the real-life differences between atypicals and conventional antipsychotics.

Schizophrenia is a chronic disease characterized by periods of relative stability interrupted by acute episodes (or relapses). The course of the disease may vary considerably between patients. Patient histories show considerable inter- and even intra-individual variability. We provide a critical assessment of the advantages and disadvantages of three modelling techniques that have been used in schizophrenia: decision trees, (cohort and micro-simulation) Markov models and discrete event simulation models. These modelling techniques are compared in terms of building time, data requirements, medico-scientific experience, simulation time, clinical representation, and their ability to deal with patient heterogeneity, the timing of events, prior events, patient interaction, interaction between co-variates and variability (first-order uncertainty). We note that, depending on the research question, the optimal modelling approach should be selected based on the expected differences between the comparators, the number of co-variates, the number of patient subgroups, the interactions between co-variates, and simulation time. Finally, it is argued that in case micro-simulation is required for the cost-effectiveness analysis of schizophrenia treatments, a discrete event simulation model is best suited to accurately capture all of the relevant interdependencies in this chronic, highly heterogeneous disease with limited long-term follow-up data.

The cost-effectiveness estimates presented in this article support the NICE guidelines for the use of antiplatelets for the prevention of cardiovascular events. Based on these pharmacoeconomic data alone, aspirin should be prescribed for primary or secondary prevention among patients at high risk of cardiovascular events, dipyridamole for the secondary prevention of stroke (for a maximum of 5 years), and clopidogrel for the treatment of symptomatic cardiovascular disease or acute coronary syndrome (for a maximum of 2 years). The cost effectiveness of antiplatelets hinges on the patient's initial risk, the risk reduction associated with treatment, and the price of the treatment. Evidence suggests that the cost effectiveness of antiplatelets can be optimized by individualising the treatment decision based on patient risk and expected risk reduction.

The DES model predicts that increases in compliance may lead to considerable cost savings and health improvements. Therefore, when determining the cost effectiveness of a new antipsychotic, efficacy rates from clinical trials should not be taken at face value, but should be interpreted in tandem with expectations concerning compliance, in light of product characteristics such as adverse effects. These results further suggest that efforts to improve compliance among patients with schizophrenia are expected to prove cost effective if compliance gains and the resulting health improvements and cost savings are in balance with the additional costs.

Although the present analysis is based in part on indirect comparisons and on trials not designed or statistically powered to specifically test the early benefits hypothesis, it suggests that atorvastatin's assumed early reduction of cardiovascular events partly offsets the acquisition price difference between atorvastatin and generic simvastatin in various groups of high-risk patients newly initiated on statin treatment.