Analytical approach:
A fixed-time advanced Monte Carlo microsimulation with quarterly cycles was used to assess the cost-effectiveness of the interventions under study. The authors reported that the model was developed in consultation with experts in the field and by an academic health economist. The time horizon was one year. The authors reported that the perspective adopted in the economic analysis was that of a third-party health care system payer.
Effectiveness data:
Most of the clinical and effectiveness parameters were derived from published literature. Expert opinion was used where no estimates were identified from the literature. All input parameters were reported. The main effectiveness estimate used in the model was level of adherence to therapy derived from published trials.
Monetary benefit and utility valuations:
Utility data were derived from an expert panel who used published disease-specific utility values and assigned these to each of the nine health state combinations. The authors reported that further details of this analysis were published elsewhere (Furiak, et al. 2009, see 'Other Publications of Related Interest' below for bibliographic details).
Measure of benefit:
The measure of benefit was quality-adjusted life-years (QALYs).
Cost data:
The direct costs included medications (acquisition and administration) and the treatment of patients with schizophrenia and treatment-emergent adverse events. The treatment of schizophrenia included in-patient treatment, day hospital treatment, emergency room services, physician visits, mental health clinic visits, home care, group interventions, nutritionist visits, nurse visits, and ambulance transport. The costs of treatment-emergent adverse events included treatment for diabetes, hyperlipidaemia, extrapyramidal symptoms, and dyskinesia, and metabolic monitoring. These costs were derived mostly from published literature; expert opinion was used where information was not identified. Details of resource use were presented. All costs were reported in 2009 prices. The currency was US dollars ($).
Analysis of uncertainty:
A series of one-way sensitivity analyses was used to assess the impact of varying the model parameters. A probabilistic sensitivity analyses was undertaken by placing distributions around three key drivers of the model results: adherence levels, rates of relapse and persistence rates. Further probabilistic analyses were performed by sampling two of the three key parameters and then modifying the third.