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An economic evaluation of surgery for temporal lobe epilepsy |
Wiebe S, Gafni A, Blume W T, Girvin J P |
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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 Performing surgery in the treatment of adults with difficult to control temporal lobe epilepsy (TLE).
Economic study type Cost-effectiveness analysis.
Study population Patients with difficult to control TLE.
Setting Hospital. The economic study was conducted in Ontario, Canada.
Dates to which data relate Effectiveness data were collected from studies published between 1965 and 1993. Resource use data related to the period August 1992 to March 1993. 1993 prices were used.
Source of effectiveness data Effectiveness data were derived from a review of previously completed studies, and local experience alongside a panel of experts.
Modelling The costs and consequences of surgical versus medical treatment of TLEwere evaluated using decision-analysis modelling based on an intention to treat approach.
Outcomes assessed in the review The main health outcome assessed in the review was the probability of seizure-free outcome based on intention to treat.
Study designs and other criteria for inclusion in the review English language literature from 1965 to 1993, and studies with more than 50 patients were the main inclusion criteria considered. According to the authors, the study designs of the primary studies included in the review were uncontrolled case series with "before and after" analyses.
Sources searched to identify primary studies MEDLINE (1965-1993) was searched and standard epilepsy textbooks were used.
Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data A group of experts (epilepsy specialists and field workers) reviewed the data from the literature and provided consensus for conflicting information on clinical outcomes and probabilities, inpatient and outpatient management, and outcomes for which reliable information was not available.
Number of primary studies included About 30 studies were included in the review.
Methods of combining primary studies Investigation of differences between primary studies A group of experts (epilepsy specialists and field workers) reviewed these data and provided consensus for conflicting information on clinical outcomes and probabilities.
Results of the review The probability of seizure-free outcome for the surgical treatment was 0.55 (0.43 - 0.68) versus 0.12 (0 - 0.25) for the medical treatment.
Methods used to derive estimates of effectiveness Estimates of effectiveness were also derived by an expert panel and local experience.
Estimates of effectiveness and key assumptions The probability of a patient in the surgical programme not being operable was 0.15.
Measure of benefits used in the economic analysis The benefit measure was the number of seizure-free patients per 100 treated patients over a time horizon of 35 years.
Direct costs Costs were discounted. Quantities were not reported separately from the prices. Cost items were reported separately. Direct health service costs were used in the analysis and included hospital costs, physician fees, antiepileptic drugs (AEDs), blood tests, dental services, community, social and support services, transportation, ambulance, emergency room, EEG studies, non-surgical epilepsy-related hospitalisations, pre-surgical intervention and surgery. The perspective adopted in the analysis was that of a third-party payer or health insurer. Physicians' costs were obtained from the Ontario Health Insurance Plan's fee schedule; hospital costs were standard costs; and outpatient costs were based on market prices. Resource use estimation was based on 3 sources: a survey of 33 outpatients in south-western Ontario using a standardised questionnaire, an expert panel for consensus on resources, and a small study including 30 patients who underwent temporal lobectomy for epilepsy from August 1992 to March 1993 at the study site. All costs were projected for 35 years. 1993 price data were used.
Currency Canadian dollars (Can$1.00 = US$0.76).
Sensitivity analysis Extensive one and two-way sensitivity analyses were performed on parameters subject to uncertainty. Threshold analyses were also performed.
Estimated benefits used in the economic analysis Surgically treating 100 patients for 35 years resulted in 57 seizure-free patients, while medical treatment led to 12.
Cost results The discount rate was 5%. Surgical treatment for 100 patients for 35 years resulted in a cost of $8,117,911 versus $10,741,425 for the medical treatment.
Synthesis of costs and benefits The surgical approach was the dominant strategy with incremental positive benefit and incremental negative cost. Despite not being methodologically required, the authors calculated the total cost per seizure-free patient as being $895,119 and $142,419 for the medical and surgical treatments, respectively. The threshold duration for the two costs to become equivalent was 8.5 years. As long as the effectiveness of surgical treatment was more than 41% and that of medical treatment less than 30%, the surgical option remained less costly. Overall, the sensitivity analysis established the robustness of the results over a wide range of reasonable values for the parameters of the model.
Authors' conclusions Available evidence indicates that TLE surgery is more effective and cheaper than medical treatment. However, adequately designed, controlled trials are necessary to determine more accurately and comprehensively the effectiveness of each therapeutic alternative.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparator is clear. Validity of estimate of measure of effectiveness The internal validity of the estimates of effectiveness should be assessed in the light of the lack of randomised controlled trials in the literature, and the fact that, as noted by the authors, the results relied heavily on retrospective studies. Validity of estimate of costs Quantities of resources were not systematically reported separately from the costs. However, adequate details of methods of cost estimation were given. Other issues The results of the study are likely to be generalisable to other settings or countries given the established robustness of the results to wide variations in the parameters of the analysis. Source of funding Partly funded by an Abbot educational grant for 1993-1994.
Bibliographic details Wiebe S, Gafni A, Blume W T, Girvin J P. An economic evaluation of surgery for temporal lobe epilepsy. Journal of Epilepsy 1995; 8(3): 227-235 Indexing Status Subject indexing assigned by CRD MeSH Adult; Anticonvulsants /therapeutic use; Cost-Benefit Analysis; Decision Trees; Epilepsy, Temporal Lobe /surgery /drug therapy; Female; Humans; Male; Middle Aged; Research Support, Non-U.S. Gov't; Seizures /prevention & control AccessionNumber 21995000964 Date bibliographic record published 30/11/1999 Date abstract record published 30/11/1999 |
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