Assessing Costs Using the Treatment Inventory Cost in Psychiatric Patients (TIC-P), TIC-P Mini and TIC-P Midi.

The Treatment Inventory Cost in Psychiatric patients (TIC-P) instrument is designed to measure societal costs in patients with psychiatric disorders and to be applied in economic evaluations. Efforts have been made to minimize respondents' burden by reducing the number of questions and meanwhile retaining the comprehensiveness of the instrument. Previously, a TIC-P Mini version and a TIC-P Midi version were developed and tested in a predominantly inpatient patient population.The aims of this study are to examine the comprehensiveness of the abridged questionnaires in estimating the societal costs for patients with anxiety or depressive disorders and to assess the impact of productivity costs on the total costs.The comprehensiveness of the abridged versions of the TIC-P was assessed in four populations: a group of primary care patients with anxiety disorders (n=175) and three groups of patients with major depressive disorders in various outpatient settings (n=140; n=125; and n=79). Comprehensiveness was measured using the proportion of total health care costs and productivity costs covered by the abridged versions compared to the full-length TIC-P. Costs were calculated according to the guidelines for costing studies using the Dutch costing manual.Our results showed that the TIC-P Mini covered 26%-64% of health care costs and the TIC-P Midi captured 54%-79% of health care costs. Health care costs in these populations were predominantly dispersed over primary care, outpatient hospital care, outpatient specialist care and inpatient hospital care. The TIC-P Midi and TIC-P Mini captured 22% and 0% of primary care costs respectively. In contrast, inpatient hospital care costs and outpatient specialist mental health care costs were almost fully included in the abridged versions. Costs due to lost productivity as measured by the full-length TIC-P were substantial, representing 38% to 92% of total costs.A reduction of the number of items resulted in a substantial loss in the ability to measure health care costs compared to the full-length TIC-P, because these outpatient populations consumed health care from a variety of health care providers. Two limitations of the study need to be stressed. Firstly, the number of patients in each of the four studies was relatively small. However, results were consistent over the four studies despite the small number of patients. Secondly, we did not take costs of medication into account.In developing mental health policy, it is important to include considerations on cost-effectiveness. Increasing the evidence on instruments to measure costs from a societal perspective may support policymakers to adopt a broader perspective.The TIC-P Mini is not suitable to capture health care costs in outpatients with anxiety or depressive disorders. The comprehensiveness of TIC-P Midi compared to the full-length TIC-P varied. The TIC-P Midi should therefore be revised in order to better capture costs in all patient groups.