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Direct cost of depression: analysis of treatment costs of paroxetine versus imipramine in Canada |
Lapierre Y, Bentkover J, Schainbaum S, Manners S |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Paroxetine (selective serotonin reuptake inhibitor) and Imipramine (tricyclic antidepressant).
Economic study type Cost-effectiveness analysis.
Study population The study modelled individuals with moderate to severe depression.
Setting Primary care. The economic study was carried out in Canada.
Dates to which data relate The effectiveness and resource use data were primarily obtained from studies published in 1991 and 1993 respectively. The unit costs were obtained from publications from 1988, 1989, 1991 and 1992.
Source of effectiveness data Effectiveness data were derived from a single study and the authors' assumptions.
Link between effectiveness and cost data Costing was not undertaken on the same patient sample but was applied to a hypothetical patient cohort. Costs were collected retrospectively.
Study sample A total of 717 outpatients were included in the study.
Study design Randomized-controlled trial (double-blind). The duration of follow-up was six weeks. The study used placebo as a control.
Analysis of effectiveness "Initial Response" was the primary health outcome used in the analysis and this was measured in the form of continuation rates (percent response/tolerance to initial therapy)
Effectiveness results The continuation rates for paroxetine and imipramine were 57.5% and 46.4% respectively.
Clinical conclusions The study reported comparable therapeutic efficacy with the two active treatments.
Modelling A computer-simulated decision tree model of the therapeutic options and sequelae in the management of depression was used to determine annual direct costs. The model aimed to reflect "normal practice".
Methods used to derive estimates of effectiveness Estimates of effectiveness were the authors' assumptions based on results for relapse rates at six months from a double-blind clinical trial of 135 patients with major depression who had previously responded to an 8-week trial of paroxetine and from a "long term trial" (for imipramine).
Estimates of effectiveness and key assumptions The estimated 6-month relapse rates were 5% with paroxetine and 20% with imipramine. To adopt a conservative approach, the model doubled the paroxetine relapse rate (to 10%) and halved the imipramine relapse rate (to 10%).
Measure of benefits used in the economic analysis Benefits were measured by means of the initial response rate (continuation rate).
Direct costs The estimation of the quantities of resource use were based on two separate focus group panels of psychiatrists and general practitioners or family physicians with interests in psychiatry. The estimation of costs was based on modelling (decision tree). Monetary values for physician and hospital services were obtained from the Ontario Ministry of Health. The cost of generic imipramine and paroxetine was obtained from the Ontario Drug Benefit Formulary and SmithKline Beecham Pharma (personal communication), respectively. Costs, which were estimated for a 12 month period, were not discounted or analysed separately with respect to quantities. The costs included in the analysis related to hospitalizations, drug acquisition costs, and costs associated with relapses. The unit costs applied to resources used were obtained from studies published in 1988, 1989, 1991 and 1992.
Sensitivity analysis Sensitivity analysis was performed on 4 variables which were identified as having a strong bearing on the results: (1) drug price; (2) hospitalization costs; (3) relapse rate; and (4) continuation rate.
Estimated benefits used in the economic analysis Paroxetine was associated with an initial response rate of 57.5%. Imipramine had a corresponding figure of 46.4%.
Cost results The annual direct costs of managing a patient with moderate to severe depression were $1,697 with paroxetine, and $1,793 with imipramine, a difference of $96 per patient per year.
Synthesis of costs and benefits Costs and benefits were not combined. The sensitivity analysis suggests that the over-all cost of care is relatively insensitive to drug costs and relapse rates after receiving a 6 month course of either therapy. Hospitalization costs were varied from $0.00 to $10,000 per 21 day stay (baseline $7,872). At $0.00, the overall cost of care was comparable in the 2 treatment arms. As inpatient costs increased, the cost of imipramine treatment increased relative to paroxetine. Paroxetine was less costly than imipramine, the former's continuation rate being >= 47% against a corresponding value of 46.4% for the latter.
Authors' conclusions According to the present results, the first-line management of moderate to severe depression with paroxetine would be expected to save about $96 per patient over a 12-month period compared to first-line treatment with imipramine. This study and previous evidence suggest that paroxetine is a cost-effective alternative to imipramine in the context in question.
CRD Commentary Whilst modelling data may be a low cost method of producing cost-effectiveness analyses, it may not represent an accurate reflection of clinical practice. The author acknowledged this caveat. This is not to say that a clinical trial will produce results which are more reliable, valid and robust, but it is felt that results from a well conducted RCT, for example, can be more confidently generalised. The study, including sensitivity analysis of four variables, is, per se, robust and the results could be used in conjunction which those from other clinical studies. A broader perspective (i.e. societal) may be relevant to the context of the study since, according to the authors, cost-shifting factor could be influencing the results to an important extent. The study did not clearly report the price year used in the analysis or the currency unit. The authors made clear that the cost analysis reflected the physician practice and costs of Ontario and, therefore the corresponding results may not be generalisable to other regions or countries.
Source of funding Supported by a grant from SmithKline Beecham Pharma.
Bibliographic details Lapierre Y, Bentkover J, Schainbaum S, Manners S. Direct cost of depression: analysis of treatment costs of paroxetine versus imipramine in Canada. Canadian Journal of Psychiatry 1995; 40(7): 370-377 Indexing Status Subject indexing assigned by NLM MeSH Adolescent; Adult; Aged; Antidepressive Agents, Second-Generation /adverse effects /therapeutic use /economics; Antidepressive Agents, Tricyclic /adverse effects /therapeutic use /economics; Canada; Comparative Study; Computer Simulation; Cost-Benefit Analysis; Decision Trees; Depressive Disorder /drug therapy /psychology /economics; Direct Service Costs; Dose-Response Relationship, Drug; Double-Blind Method; Drug Administration Schedule; Female; Humans; Imipramine /adverse effects /therapeutic use /economics; Male; Middle Aged; Paroxetine /adverse effects /therapeutic use /economics; Patient Readmission /economics; Research Support, Non-U.S. Gov't; Treatment Outcome AccessionNumber 21995001092 Date bibliographic record published 31/07/1998 Date abstract record published 31/07/1998 |
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