Study population The study population comprised patients suffering from superficial femoral artery stenosis that required revascularisation.

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1 Maintenance of patency following remote superficial femoral artery endarterectomy Galland R B, Whiteley M S, Gibson M, Simmons M J, Torrie E P, Magee T R 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 Remote superficial femoral artery endarterectomy (RSFE) was examined. RSFE is a minimally invasive procedure usually carried out for stenosis affecting the whole length of the superficial femoral artery. Type of intervention Treatment. Economic study type Cost-effectiveness analysis. Study population The study population comprised patients suffering from superficial femoral artery stenosis that required revascularisation. Setting The clinical setting was a general district hospital. The economic study was performed in Reading, Berkshire, UK. Dates to which data relate The dates when the effectiveness and resource use data were gathered were not reported. The price year was not reported. Source of effectiveness data The effectiveness evidence was derived from a single study. Link between effectiveness and cost data The costing was performed on the same sample of patients used in the effectiveness study. It was performed prospectively for the intervention group (RSFE) and retrospectively for the control group (in situ bypass). Study sample No power calculations to determine the sample size were performed. Thirty patients were initially included in the RSFE group for a total of 32 symptomatic legs treated. However, RSFE was completed only in 25 cases and the remaining 7 cases received immediate femoro-popliteal bypass. The 25 RSFEs performed were compared with 25 cases in which in situ bypass was undertaken. All of the patients receiving RFSE had intermittent claudication, 3 had rest pain and 3 ulceration or gangrene. Occlusion was present in 17 cases, occlusions with stenosis in 13 cases and multiple stenoses in 2 cases. The median age of patients receiving RSFE was 64 years (range: 45-84) and 22 (out of 30) were men. Eight patients receiving in situ bypass had incapacitating claudication, 8 had rest pain and 9 ulceration or gangrene. The Page: 1 / 5

2 median age in this group was 71 years (range: 58-89) and 16 (out of 25) were men. Study design This was a cohort study with a historical cohort that was performed in a single centre. The patients were followed up to a maximum of 33 months. The incidence of stenosis was analysed at intervals of 3 months by duplex surveillance of the vein graft. The patients who underwent in situ bypass were randomly selected from a graft surveillance database maintained by the hospital. No loss to follow-up was reported. Analysis of effectiveness The analysis of effectiveness was conducted on the basis of treatment completers only. The main health outcomes used in the analysis were the primary and primary-assisted patency at 18 months (only for patients receiving RSFE), and the number of stenoses occurring during the follow-up. The two groups were not stratified in terms of age, gender or symptoms. Patients having in situ bypass were older and had more severe clinical and angiographic disease. However, no statistical analyses were performed to investigate the significance of these differences. Effectiveness results In the RSFE group, at 18 months the primary patency was 31% and the primary-assisted patency was 63%. Seventeen stenoses were identified in the RSFE group (68%) during follow-up, of which 11 required percutaneous transluminal angioplasty (PTA). Six stenoses were identified in the bypass group (24%) during follow-up, of which 4 required PTA. One patient died of bronchial carcinoma in the RSFE group and one patient died of myocardial infarction in the bypass group. The two groups differed in when the stenoses were diagnosed. In the bypass group all stenoses occurred during the first year of follow-up, whereas 8 out of 17 stenoses occurred after one year of follow-up in the RSFE group. Clinical conclusions This study showed a lower rate of stenosis formation following vein bypass than following RSFE. In the case of endarterectomy, a significant proportion of stenoses developed after one year. This suggested the appropriateness of indefinite duplex surveillance following RSFE. Measure of benefits used in the economic analysis No summary benefit measure was used. The study has therefore been classified as a cost-consequences analysis. Direct costs Discounting was not carried out because the time horizon when the costing was performed was less than 2 years. The unit costs were reported separately from the resources used, but the quantities of resources used were only partially described. The quantity/cost boundary appears to have been that of the hospital. The categories of costs included were RSFE, bypass and PTA, hospital stay, hourly charges for the theatre and radiology suite, and maintenance. Resource use data were derived from the patients' charts and hospital databases. The source of the unit costs was not reported. There was no information on when the resource use data were gathered and the price year was not reported. Statistical analysis of costs Statistical analyses of the costs were not carried out. Page: 2 / 5

3 Indirect Costs The indirect costs were not included in the analysis. Currency UK pounds sterling (). Sensitivity analysis Sensitivity analyses were not performed. Estimated benefits used in the economic analysis See the 'Effectiveness Results' section. Cost results The initial average cost per patient was 4,125 for in situ bypass versus 2,183 for RSFE. This difference mainly arose from the longer postoperative stay for bypass (mean 12.5 days) than for RSFE (mean 1.2 days). However, the cumulative costs following RSFE were higher than those following bypass. At 15 months' follow-up, the average cost per patient was 808 for RSFE versus 122 for bypass. The average cost per patent vessels was 663 for RSFE versus 133 (for patent graft) in the case of bypass. These follow-up costs excluded the cost of duplex scanning that would have increased the cumulative costs following RSFE. Synthesis of costs and benefits Not relevant. Authors' conclusions The initial cost gains following remote superficial femoral artery endarterectomy (RSFE) were largely lost whilst attempting to maintain patency. CRD COMMENTARY - Selection of comparators The rationale for the choice of the comparator was clear. RSFE was compared with femoro-popliteal bypass because both interventions are usually carried out for disease affecting the whole length of the superficial femoral artery. Also, because bypass had shown the best results for revascularising long superficial femoral artery occlusion. You should decide whether they are valid comparators in your own setting. Validity of estimate of measure of effectiveness The effectiveness analysis used a cohort study with a historical cohort. The authors stated that there were differences between the two groups in terms of the patients' demographics and severity of disease. Therefore, the comparability of the two groups was uncertain. In addition, no statistical analysis was performed to estimate the significance of these differences. No power calculations were performed and the sample size appears to have been relatively small. The authors appear to have presented the effectiveness results selectively, although this may have arisen because the main focus of the study was the costs. For example, while primary patency and primary-assisted patency at 18 months were presented in the case of RSFE, no information was given for bypass. Also, no statistical analyses were performed to assess the significance of differences between the two groups in the main outcomes. The basis of the analysis was treatment completers only. However, the authors acknowledged that the use of an intention to treat analysis might have changed the results of the study. Page: 3 / 5

4 Validity of estimate of measure of benefit No summary benefit measure was used in the economic analysis. The analysis was therefore categorised as a costconsequences study. Validity of estimate of costs All the categories of costs appear to have been included given the perspective of the analysis. The unit costs were reported separately from resource use, but the quantities of resource use were only partially described. No statistical or sensitivity analyses of the costs were performed. There was no information on when the resource use data were gathered and the price year was not reported. These factors limit the reproducibility of the results in other settings. If all patients enrolled in the study had been included at analysis, it is likely that this would have increased the costs associated with RSFE, given that patients who did not complete endarterectomy received bypass. Other issues The authors compared the clinical results of their analysis with other published studies and found similar effectiveness outcomes. However, no comparison was performed on the cost side. The issue of generalisability of the results was not addressed and the authors did not perform any sensitivity analyses. Implications of the study The results of this study suggested that, although RSFE might appear attractive given the short length of stay required, the initial reduction in costs is likely to be offset by the increased costs of maintaining patency. Source of funding None stated. Bibliographic details Galland R B, Whiteley M S, Gibson M, Simmons M J, Torrie E P, Magee T R. Maintenance of patency following remote superficial femoral artery endarterectomy. Cardiovascular Surgery 2000; 8(7): PubMedID Other publications of related interest Galland RB, Whiteley MS, Gibson M, Simmons MJ, Torrie EP, Magee TR. Remote superficial femoral artery endarterectomy: medium-term results. European Journal of Vascular and Endovascular Surgery 2000;19: Indexing Status Subject indexing assigned by NLM MeSH Aged; Aged, 80 and over; Arteriosclerosis /surgery; Endarterectomy /economics /methods; Female; Femoral Artery /pathology /surgery /ultrasonography; Humans; Male; Middle Aged; Minimally Invasive Surgical Procedures; Postoperative Period; Secondary Prevention; Stents; Ultrasonography, Doppler, Duplex /economics; Vascular Patency AccessionNumber Date bibliographic record published 29/02/2004 Page: 4 / 5

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