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A model to evaluate the cost-effectiveness of oral therapies in the management of patients with major depressive disorders |
Einarson T R, Arikian S, Sweeney S, Doyle J |
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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 Oral antidepressant therapies: venlafaxine, a serotonin norepinephrine reuptake inhibitor (SNRI); tricyclic antidepressants (TCAs); selective serotonin reuptake inhibitors (SSRIs); and heterocyclic antidepressants (HCAs)for patients with major depressive disorders.
Economic study type Cost effectiveness analysis.
Study population Patients aged 18 years or over with a major depressive disorder.
Setting In-patient and out-patient settings in the USA.
Dates to which data relate The dates of the published papers reviewed were not given. Cost or price dates were not given.
Source of effectiveness data Review of published studies.
Link between effectiveness and cost data The costing was not undertaken on the same patient sample.
Modelling A decision analysis model was used to estimate final costs and benefits.
Outcomes assessed in the review Success rates (defined as a 50% reduction from baseline in the Hamilton Rating scale for depression), relapse rates and adverse events.
Study designs and other criteria for inclusion in the review Double-blind randomised controlled trials in patients aged over 19 years of age treated as inpatients or outpatients for major depressive disorder. Studies had to have:
(a) a 7 day (within a 3 day range) placebo period before the start of treatment,
(b) patients who were given a minimum of 4 weeks of the treatment,
(c) doses given within the therapeutic range
and (d) clearly defined success and response rates.
Studies that focused only on elderly patients, concurrent psychological anomalies or organic anomalies were also excluded. Non-comparative trials were reviewed for side-effects and relapse rates.
Sources searched to identify primary studies No validity criteria for included studies.
Criteria used to ensure the validity of primary studies Studies had to be prospective double-blind trials.
Methods used to judge relevance and validity, and for extracting data Two blinded reviewers examined the eligibility of each study. Inter-reviewer differences regarding study eligibility were arbitrated by a third, non-blinded reviewer.
Number of primary studies included 34 studies met the criteria for the meta-analysis. No published studies of the SNRI only data on file.
Methods of combining primary studies A meta-analysis was carried out using the random effects model of DerSimonian and Laird.
Investigation of differences between primary studies Studies were considered separately for inpatient, outpatient and long term care.
Results of the review In the inpatient analysis, SNRIs had the highest success rate (62.4%). The other mean success rates were: TCAs 50.9%; HCAs 49.2%; SSRIs 30.3%. In the outpatient analysis, SNRIs again had the highest success rate (64.6%). Success rates for other drugs were: HCAs 58.9%; SSRIs 55.6%; and TCAs 49.9%.
Measure of benefits used in the economic analysis Symptom-free days was the measure of benefit used i.e. days where there was no contact with the health service. A decision analysis model was used where the clinical management of patients with major depressive disorders was determined by a panel of 5 psychiatrists. The analytic time frame of the model was 1 year. An inpatient and an outpatient treatment model were investigated.
Direct costs Only health service costs were considered, i.e. drug costs, medical care costs (hospitalisation, clinicians' visits and laboratory tests) and cost of adverse events. The quantities of resources were judged by the specialist panel. The costs were estimated through a survey of 3 US health maintenance organisations. Quantities and costs were not presented separately. The expected cost of therapy was calculated by multiplying the cost of each outcome by the probability of each branch of the decision tree.
Statistical analysis of costs The mean cost of care in the 3 health organisations and the standard deviation were calculated.
Sensitivity analysis A break-even analysis was performed. The model was called rank order stability analysis. Elasticities were calculated to test the sensitivity of the model's conclusions to changes in the key parameters such as the length of therapy, drug cost and success rate.
Estimated benefits used in the economic analysis At the 1 year follow-up, the number of symptom-free days for the inpatient model was: SNRIs 219, HCAs 189, SSRIs 150 and TCAs 173. For the outpatient model the number of symptom-free days were: SNRIs 186, HCAs 191, SSRIs 189 and TCAs 172.
Cost results Total costs (including drug costs, medical care costs, laboratory costs and the costs of adverse events ) per patient for the inpatient model were as follows: HCA $11,492, SNRIs $12,201, SSRIs $11, 864 and TCAs $12,513. For the outpatient model the figures were: HCA $1896, SNRIs $2401, SSRIs $2412 and TCAs $3061. Therefore without considering efficacy, HCAs were the lowest cost treatment.
Synthesis of costs and benefits The cost per symptom-free day for the inpatient setting of the four therapies was: SNRI $93, HCA $108, SSRI $146 and TCA $124. Among the out-patient setting it was: SNRI $23, HCA $20, SSRI $25, TCA $29. This was a generic pricing analysis, and in the brand pricing analysis (details not given) SNRIs appeared the most cost-effective treatment in both settings. The sensitivity analysis indicated a high degree of stability for the results though more sensitivity to the treatment efficacy of SNRIs.
Authors' conclusions The model suggested that SNRI therapy demonstrated the highest cost-effectiveness in an inpatient setting when using both brand and generic acquisition costs. For outpatient settings, the generic heterocyclic anti-depressants demonstrate the highest level of cost-effectiveness.
CRD Commentary The review on which the treatment effectiveness was estimated did not indicate the search strategy used, so relevant RCTs may have been missed. The inclusion criteria excluded studies which showed more traditional oral therapies to be more effective. The estimate of the effectiveness of the SNRIs was based on unpublished data held by the producer company and so cannot be examined for its quality or accuracy. The validity of deriving symptom-free days was not established. Data on resource use were not based on actual records but expert opinion and may be biased. These data were not presented separately. Prices were based on a survey of costs. The assumptions of effects and resource use were based on the situation in the USA and may not be generalisable to the UK due to differences in the patterns of out-patient care and hospitalisation.
Source of funding Research funded by Wyeth-Ayerst Laboratories, Philadelphia, Pennsylvania.
Bibliographic details Einarson T R, Arikian S, Sweeney S, Doyle J. A model to evaluate the cost-effectiveness of oral therapies in the management of patients with major depressive disorders. Clinical Therapeutics 1995; 17(1): 136-153 Indexing Status Subject indexing assigned by NLM MeSH Administration, Oral; Antidepressive Agents /economics /therapeutic use; Cost-Benefit Analysis; Costs and Cost Analysis; Depressive Disorder /drug therapy /economics; Drug Therapy, Combination; Economics, Pharmaceutical; Humans; Meta-Analysis as Topic; Models, Economic; Sensitivity and Specificity AccessionNumber 21995000403 Date bibliographic record published 30/11/1997 Date abstract record published 30/11/1997 |
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