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A Markov process analysis comparing the cost effectiveness of maintenance therapy with citalopram versus standard therapy in major depression |
Nuijten M J, Hardens M, Souetre E |
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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 Pharmaceutical: citalopram, doxepin (Sinquan), doxepin (Aponal), trimipramine (Stangyl), amitriptyline (Saroten).
Economic study type Cost-effectiveness analysis.
Study population Patients with major depression. No other patients' characteristics were provided.
Setting Primary care. The economic study was carried out in Germany.
Dates to which data relate The date of clinical data was not specified. All costs were in 1993 Deutschmarks.
Source of effectiveness data The clinical data regarding the treatment patterns and their associated transition probabilities (for the modelling) were obtained from the published literature and US clinical practice guidelines.
Modelling A Markov process analysis was used to model the health status and economic outcomes.
Outcomes assessed in the review The main outcome measures were time without depression.
Study designs and other criteria for inclusion in the review The response rates used in the study were based on a meta-analysis of antidepressant medications. No inclusion or exclusion criteria were stated.
Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included Methods of combining primary studies The response rates used in the study were based on a meta-analysis of antidepressant medications. The response rate of standard therapy was a weighted average of the response rates of the three most used antidepressants in Germany (doxepin (Sinquan), doxepin (Aponal), trimipramine (Stangyl), amitriptyline (Saroten)) according to the proportion of their market share.
Investigation of differences between primary studies The authors recognised that the model was based on data derived from clinical trials which have low external validity because of: (i) inclusion and exclusion criteria; and (ii) protocol-drive healthcare utilisation. Thus, both the study population and the medical care given differ from routine practice.
Results of the review Compared with standard therapy, time without depression was greater with the treatment of citalopram (8.2 vs. 7.6 months). The time without depression expressed as a percentage of the total treatment period of 12 months was 68.3% using citalopram and 63.3% using standard therapy.
Measure of benefits used in the economic analysis Time without depression. A Markov process analysis was used to model the health status, mainly using results from other studies as input variables. The authors stated that this represented a convenient way of modelling the long-term evolution of health states over successive periods.
Direct costs No discounting was undertaken given that the follow-up period was for 12 months only. Resources used included: drugs, consultations, hospitalisation, and psychotherapy. However, costs and quantities of resource use were not analysed separately. The cost perspective was that of the German statutory sickness fund third-party payer. Resource use was estimated in that data was collected from other clinical trials in the form of a meta-analysis and then used as input variables in the Markov model in order to calculate the transition probabilities of moving between three mutually exclusive health states. The patient's progression through these states was divided into 6 cycles of 2 months. A 2-month cycle was chosen because this interval closely approximated the time of the sequential therapeutic stages. The estimation of costs was based on actual data from other clinical studies. Given that at the time of the study citalopram was not registered, the authors used the weighted average daily treatment costs of the four leading antidepressants in Germany (doxepin (Sinquan), doxepin (Aponal), trimipramine (Stangyl), amitriptyline (Saroten)), according to the proportion of their market shares. Costs referred to 1993.
Indirect Costs No discounting was undertaken given that the follow-up period was for 12 months only. Indirect costs were based on the number of working days lost, which were valued by using GNP per capita (DM140 per day). The cost perspective was that of the German statutory sickness fund third-party payer. Costs refer to 1993.
Sensitivity analysis A sensitivity analysis was performed on the response and relapse rates associated with citalopram treatment.
Estimated benefits used in the economic analysis Compared with standard therapy, time without depression was greater for the treatment of citalopram (8.2 vs. 7.6 months). The time without depression expressed as a percentage of the total treatment period of 12 months was 68.3% using citalopram and 63.3% using standard therapy.
Cost results The direct, indirect and total costs per patient treated with citalopram over a 12 month period were DM 3,764, DM 4,221, and DM 7,985, respectively. The costs for standard therapy were DM 4,577 (direct), DM 7,371 (indirect), and DM 11,948 (total). Total direct costs for citalopram treatment and standard therapy were DM3,764 and DM4,577, respectively.
Synthesis of costs and benefits Citalopram was the dominant strategy.
Authors' conclusions The results of the analysis indicated that one year's maintenance treatment with citalopram was a cost-effective strategy for patients with major depression. However, although confirming results found in two other independent studies, methodological issues of this study suggested that further economic evaluation on maintenance citalopram versus standard therapy was warranted to confirm the findings.
CRD Commentary The authors correctly highlighted caveats in the analysis of the study. The data used in the study originated from studies with different designs and methodologies. The authors recognised that the model was based on data derived from clinical trials which have low external validity because of: (i) inclusion and exclusion criteria; and (ii) protocol-drive healthcare utilisation. Thus, both the study population and the medical care given differ from routine practice. Given this problem, areas b.3.2, b.3.4 ,b.3.5, and b.3.6 in the CRD reviewers' guidelines are not fulfilled. These areas relate to the listing of study designs of studies included in the paper, a clear specification of the criteria used to ensure the validity of primary studies, a specification of the judgement criteria appied by the authors to assess the validity of primary studies and details of the number of studies included.
Implications of the study The results of this study have confirmed the finding of two other studies that have examined the clinical and economic effects of long-term maintenance treatment with antidepressants. However, since there are methodological problems with this study further analysis is required.
Source of funding Funded by H. Lundbeck A/S, Denmark.
Bibliographic details Nuijten M J, Hardens M, Souetre E. A Markov process analysis comparing the cost effectiveness of maintenance therapy with citalopram versus standard therapy in major depression. PharmacoEconomics 1995; 8(2): 159-168 Indexing Status Subject indexing assigned by NLM MeSH Amitriptyline /economics /therapeutic use; Antidepressive Agents /economics /therapeutic use; Antidepressive Agents, Tricyclic /economics /therapeutic use; Citalopram /economics /therapeutic use; Cost-Benefit Analysis; Decision Support Techniques; Depressive Disorder /drug therapy /economics /psychology; Doxepin /economics /therapeutic use; Germany; Humans; Long-Term Care /economics; Markov Chains; Models, Economic; Recurrence; Trimipramine /economics /therapeutic use AccessionNumber 21995000915 Date bibliographic record published 30/07/1997 Date abstract record published 30/07/1997 |
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