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A cost-effectiveness analysis of anterior temporal lobectomy for intractable temporal lobe epilepsy |
King J T, Sperling M R, Justice A C, O'Connor M 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 Anterior temporal lobectomy (ATL) for medically intractable temporal lobe epilepsy.
Study population Patients suffering from medically intractable temporal lobe epilepsy, defined as complex partial or secondarily generalised seizures occurring at a rate of at least one every 1 to 2 months, and failure to respond to at least three different antiepileptic medications (e.g., phenytoin, carbamazepine, phenobarbital, valproate, gabapentin, felbamate, lamotrigine).
Setting Hospital. The economic study was conducted in Cleveland, Ohio and Philadelphia, Pennsylvania, USA.
Dates to which data relate Effectiveness data were collected between 1987 and 1993. All costs are expressed in 1994 US dollars, using the US City Average Consumer Price Index for medical care for cost conversions.
Source of effectiveness data Most data were derived from the study conducted by the authors, but some probabilities of moving between health states used in the model come from published clinical trials, expert consensus, clinical judgement and actuarial tables (such as death as a surgical outcome, and quality of life values as reported by Vickrey et al).
Link between effectiveness and cost data Costing was only partially undertaken on the same patient sample as that used in the effectiveness analysis.
Study sample During 1993, 51 patients with suspected temporal lobe epilepsy were eligible for evaluation and received an outpatient assessment followed by an admission to the Graduate Hospital for surface video-EEG monitoring. Fifteen patients (29%) required depth electrode video-EEG monitoring, and 34 (67%) ultimately underwent ATL. The post-surgery follow-up was for a minimum of 1 year. To obtain more accurate data on outcomes following ATL for temporal lobe epilepsy, the authors also used a larger cohort of 181 patients undergoing ATL between 1987 and 1993.
Study design This was a case series study.
Analysis of effectiveness The analysis was based on intention to treat, as it included the patients who entered the evaluation and treatment protocol but who were rejected for surgery. The main health outcomes used in the analysis were classified as seizure free (no auras or seizures), auras (auras and simple seizures) and seizures (complex partial and/or general seizures). Postoperative death rate was also considered.
Effectiveness results The seizure status post surgery was as follows: with a minimum follow-up period of 1 year, 53% of the 34 patients who underwent surgery were free of seizures, 16% experienced only auras and 31% still had seizures. In the first year after evaluation for ATL, 36% of all patients (51) were free of seizures, 11% had auras, and the remaining 53% were not eligible for surgery, died, or did not respond to surgery.
Clinical conclusions ATL can eliminate, or drastically reduce, seizures in the majority of patients.
Modelling A Markov state transition model was developed in order to compare evaluation for possible surgical treatment to continued medical therapy for patients with intractable temporal lobe epilepsy. The health states in the Markov model were as follows: (1) seizures, (2) auras, (3) seizure free while receiving medications, (4) seizure free in the absence of medications and (5) death. Each health state has an assigned quality of life value and an associated direct medical cost. The model was run until all patients had died.
Outcomes assessed in the review As well as the case series study data was also derived from published research. The outcomes assessed in the review included surgical outcomes, quality of life and long term mortality rate.
Study designs and other criteria for inclusion in the review 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 Eight studies were included in the review.
Methods of combining primary studies Investigation of differences between primary studies Results of the review Death rate after surgery was 0.25%, and quality of life values of the different states were as follows: 0.82 - seizure free, 0.76 - auras, 0.67 - seizures. Long-term death rate was age-stratified and there was no change in mortality rate after successful epilepsy surgery.
Measure of benefits used in the economic analysis Quality-adjusted life years (QALYs0 were used as the measure of benefit in the economic analysis. The postsurgical seizure classification system and corresponding quality of life values reported by Vickrey and colleagues were used in the model, as follows: patients who were seizure free postoperatively were assigned a value of 0.82, those who experienced simple seizures and/or auras were assigned 0.76, and patients with complex partial or generalised seizures wee given 0.67, on a scale of 0.0-1.0. By convention, death was assigned a value of 0.
Direct costs Direct medical costs associated with outpatient evaluation, hospitalisation, surgery, antiepileptic drugs, and lifetime outpatient treatment were considered. All costs are expressed in 1994 US dollars, and discounted using a 5% and 3% rate. Costs/quantities were reported separately.
Statistical analysis of costs Indirect Costs Patients= earnings after ATL were considered.
Sensitivity analysis Sensitivity analyses were performed by altering the input value of individual variables within clinically reasonable ranges to assess the effects on the model's conclusions of the assumptions made in the baseline analysis. The boundaries of the clinically reasonable ranges were determined from the published literature, 95% confidence intervals of the Graduate Hospital outcomes point estimates, or clinical judgement, whichever resulted in the widest range of possible values considered.
Estimated benefits used in the economic analysis Data from the baseline model indicated that evaluation for ATL provided an average of 1.1 additional QALYs compared with continued medical management.
Cost results The average cumulative discounted life-time costs for patients entering the temporal lobe epilepsy evaluation and treatment protocol (combining protocol, medication and long-term care costs) was $50,800 as opposed to $21,000 for medical management. The marginal cost of the ATL evaluation and treatment protocol was $29,800. A modest additional annual income of $5,400 was attributed to ATL patients versus pre-protocol patients.
Synthesis of costs and benefits Combining the medical and economic outcomes yielded a cost-effectiveness ratio of $27,200 per QALY. This value is comparable to accepted medical or surgical interventions (such as total knee arthroplasty or coronary artery balloon angioplasty).
Authors' conclusions The authors concluded that although further work was necessary to quantify the improvement in quality of life after epilepsy surgery, the present data indicated that ATL for treatment of intractable temporal lobe epilepsy was a cost-effective use of medical resources.
CRD COMMENTARY - Selection of comparators The selection of comparators is justified, as both treatment protocols for epilepsy were widely used in the authors' setting. You, as a database user should consider if this applies to your own setting.
Validity of estimate of measure of benefit Data do not appear to have been used selectively to prove a particular point and the choice of health outcomes is justified. The lack of randomization might have introduced biases in the study results.
Validity of estimate of costs Extensive details of the methods of quantity/cost estimation were given and no important cost items were omitted.
Other issues Cost data may not be generalisable to other settings/countries.
Bibliographic details King J T, Sperling M R, Justice A C, O'Connor M J. A cost-effectiveness analysis of anterior temporal lobectomy for intractable temporal lobe epilepsy. Journal of Neurosurgery 1997; 87(1): 20-28 Indexing Status Subject indexing assigned by NLM MeSH Adult; Cost-Benefit Analysis; Epilepsy, Temporal Lobe /physiopathology /surgery; Health Care Costs; Humans; Middle Aged; Models, Theoretical; Neurosurgery /economics; Quality-Adjusted Life Years; Survival Analysis; Temporal Lobe /surgery; Time Factors; Treatment Outcome AccessionNumber 21997000930 Date bibliographic record published 28/02/1999 Date abstract record published 28/02/1999 |
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