• Gerd Laux, Bart Heeg, Ben A van Hout, and Angelika Mehnert.
• District Hospital Gabersee, Wasserburg, Germany.
• Pharmacoeconomics. 2005 Jan 1; 23 Suppl 1: 49-61.

AbstractSchizophrenia is one of the most expensive psychiatric conditions because of high direct and indirect costs associated with the nature of the illness, its resistance to treatment and the consequences of relapse. Long-acting risperidone is a new formulation of an atypical antipsychotic drug that also offers the improvements in compliance associated with haloperidol depot. The aim of this simulation study was to compare the benefits and costs of three pharmacological treatment strategies comprising first-line treatment with long-acting risperidone injection, a haloperidol depot or an oral atypical antipsychotic agent, over a 5-year period in Germany. A discrete event simulation model was developed to compare three treatment scenarios from the perspective of major third-party payers (sickness funds and social security 'Sozialversicherung'). The scenarios comprised first-line treatment with haloperidol depot (scenario 1), long-acting risperidone (scenario 2) and oral olanzapine (scenario 3). Switches to second or third-line options were allowed when side-effects occurred or a patient suffered more than a fixed number of relapses. The model accounted for fixed patient characteristics, and on the basis of these, simulated patient histories according to several time-dependent variables. The time horizon for this model was limited to 5 years, and in accordance with German guidelines, costs and effects were discounted by between 3 and 10%. Direct costs included medication, type of physician visits and treatment location. Indirect costs were not included. Information on treatment alternatives, transition probabilities, model structure and healthcare utilization were derived from the literature and an expert panel. Outcomes were expressed in terms of the number and duration of psychotic episodes, cumulative symptom scores, costs, and quality-adjusted life-years (QALY). Univariate sensitivity analyses were carried out, as were subgroup analyses based on disease severity and for patients at high risk of being non-compliant. The long-acting risperidone strategy was calculated to avoid 0.23 and 0.33 relapses per patient, decrease the cumulative symptom score by 25 and 33 points, and decrease the costs by 2017 Euro and 6096 Euro per patient (1608 Euro and 5422 Euro discounted), compared with the haloperidol depot and olanzapine strategies, respectively, over a 5-year period (year of costing 2004). Among high-risk non-compliant patients, long-acting risperidone was estimated to avoid 0.23 and 0.47 relapses and save 4822 Euro and 10,646 Euro per patient (4107 Euro and 9490 Euro discounted), compared with the haloperidol depot and olanzapine strategies, respectively. Sensitivity analyses showed that the results were robust and mainly sensitive to changes in the reported relative effectiveness of atypical and conventional formulations for preventing symptom recurrence, and in the relative compliance with oral and long-acting formulations. In this model, long-acting risperidone is a dominant strategy compared with a haloperidol depot or oral atypical antipsychotic agent, being both more effective and less costly over a 5-year period. Results for long-acting risperidone are even more favourable among patients at high risk of being noncompliant or with more severe disease.

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