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Randomized comparison of success and adverse event rates and cost effectiveness of one long versus two short stents for treatment of long coronary narrowings |
Hoffmann R, Herrmann G, Silber S, Braun P, Werner G S, Hennen B, Rupprecht H J, vom Dahl J, Hanrath 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 The health interventions examined in the study were the use of one long stent (1LS) versus two short stents (2SS) for the treatment of patients with symptomatic coronary artery disease with a lesion of 20 to 40 mm in length.
1LS was applied as follows: lesions 20 to 24 mm, stent 24 mm; lesions 24 to 30 mm, stent 30 mm; lesions 30 to 40 mm, stent 40 mm.
2SS were applied as follows: lesions 20 to 24 mm, two stents of 12 mm; lesions 24 to 30 mm, one stent of 18 mm and one stent of 12 mm; lesions 30 to 40 mm, one stent of 24 mm and one stent of 18 mm.
All stents were GFX II or S670 (Medtronic AVE).
Economic study type Cost-effectiveness analysis.
Study population There were 2 analyses conducted in this study on different populations, one a sub-population of the other. The study population from which the first study sample was drawn comprised patients suffering from symptomatic coronary artery disease, with a lesion of 20 to 40 mm in length, in a native coronary artery 2.5 to 4.0 mm in diameter. Patients with restenotic lesions, lesions in an ostial location, heavily calcified lesions, and lesions in extremely tortuous vessels were ineligible. The second study sample comprised those patients from the first who, after being randomised and treated, had had a successful intervention and no major adverse cardiac event (MACE) within 30 days of the intervention.
Setting The setting was hospital. The economic study was conducted in Germany.
Dates to which data relate Neither dates for effectiveness and resource use nor the price year were reported.
Source of effectiveness data The effectiveness evidence was derived from a single study.
Link between effectiveness and cost data The costing was performed prospectively on the same patient sample as that used in the effectiveness study.
Study sample No power calculations were performed and no evidence was provided that the initial study sample was representative of the study population. This also applies for the sub-study sample. The method of first sample selection was not reported. The second study sample was determined according to the exclusion criteria mentioned in the study population field above. The first sample had 124 eligible patients: 62 patients (age: 62.8 +/- 9.7 years; 85% men; systemic hypertension: 32%) were included in the 1LS group and 62 patients (age: 63.3 +/- 8.8 years; 77% men; systemic hypertension: 27%) in the 2SS group. The second sample had 107 patients: 52 (84%) in the 1LS group and 55 (89%) in the 2SS group.
Study design The main study design was a randomised controlled trial. After the operator decided which stent length was more appropriate according to on-line quantitative coronary angiography (QCA) measurement, each patient was randomised for implantation of either 1LS or 2SS. The method of randomisation was not stated. However, the second analysis was conducted on sub-samples derived from patients excluded from the initial randomized study groups. These, therefore, may have lost some benefit of randomization. This was a multi-centre study but the centres were not reported. Patients were followed for six months and follow-up data were available for 84% of patients in the 1LS group and for 89% of patients in the 2SS group undergoing angiographic assessment. An operator blinded to patient allocation performed the follow-up angiographic assessment, which started after 30 days from the date of intervention for eligible patients.
Analysis of effectiveness From the first study sample, baseline clinical, demographic and angiographic data, procedural data, and in-hospital clinical outcomes were assessed. From the sub-sample, angiographic follow-up results were measured. For the first study sample, the health outcomes estimated were procedural success (defined as less than 30% final diameter stenosis in the treated lesion and the absence of major clinical complications, such as in-hospital death, Q-wave myocardial infarction, or emergency coronary bypass surgery), in-hospital success rate and major adverse cardiac event (MACE, defined as death of any origin, myocardial infarction, or a need for revascularisation). For the second study sample, angiographic follow-up outcomes, such as minimal lumen diameter, late loss, net gain, restenosis rate (diameter stenosis of 50% or more), lumen diameter proximal stent edge, lumen diameter body of stented segment, and lumen diameter distal stent edge were estimated. Study groups were shown to have been comparable in terms of baseline patient characteristics and preprocedural morphologic and quantitative angiographic lesion characteristics for the first sample but the same characteristics were not assessed for the second sample.
Effectiveness results The effectiveness results were as follows:
Procedural success was 97% (60 of 62 cases) in the 1LS group and 100% in the 2SS group, (p=0.479).
In the 1LS group there was one myocardial infarction and one cross-over due to failed stent placement. Thirteen patients in the 1LS group had more than 1 stent implanted due to either dissections at a stent edge or incomplete coverage of the lesion by 1 stent.
The in-hospital success rate was 97% in the 1LS group and 98% in the 2SS group.
MACE occurred in 5 out of 62 cases (8%) in the 1LS group and in 6 out of 62 patients (10%) in the 2SS group.
None of the angiographic follow-up outcomes reached statistical significance when comparing the two groups. In particular, the restenosis rate was 38.5% in the 1LS group and 37.5% in the 2SS group (p=0.919).
Clinical conclusions The effectiveness analysis showed that the clinical outcomes estimated in the two study groups were similar.
Measure of benefits used in the economic analysis No summary benefit measure was used in the economic analysis and no statistically significant differences were found in any of the clinical outcomes used in the effectiveness study. Thus the study was categorised as a cost-minimisation analysis.
Direct costs No discounting was performed, as the time horizon of the study was six months. Unit costs were reported separately from quantities of resources. The health service costs included in the economic evaluation were angioplasty balloon, coronary stent, and intervention time (including laboratory room and personnel). The cost/resource boundary adopted in the study was not stated. Resource consumption was estimated alongside the clinical trial, while the source of the unit costs was not stated. No price year was reported.
Statistical analysis of costs Costs were presented as mean +/- standard deviation and standard statistical analyses of costs were conducted to test for statistical significance of estimated total costs.
Indirect Costs Indirect costs were not included in the analysis.
Sensitivity analysis No sensitivity analyses were performed.
Estimated benefits used in the economic analysis Please refer to the effectiveness results reported above.
Cost results Among resource use, only the number of stents used was highly statistically significantly different between the 1LS group and the 2SS group (1.31 +/- 0.64 versus 2.16 +/- 0.41; p<0.001). The next most significant difference involved the contrast agent: 165 +/- 73 for the 1LS group versus 190 +/- 70 for the 2SS group (p=0.056). The remaining resources were similar. The estimated overall costs were Euros 1,577 +/-676 in the 1LS group and Euros 2,293 +/-666 in the 2SS group, (p<0.001).
Synthesis of costs and benefits Costs and benefits were not combined as a cost-consequences analysis was conducted.
Authors' conclusions The authors concluded that the use of one long stent proved to be safe and feasible in patients with coronary lesions of 20 to 40 mm in length. The observed restenosis rate was comparable with that of patients receiving two short stents, but costs were significantly lower with the long stent intervention.
CRD COMMENTARY - Selection of comparators The authors did not justify the choice of the two types of stents as comparators in the economic evaluation. Although several types of stents may be available, it appears that the comparison between one long stent and two short stents may be the relevant one in patients with long coronary lesions. You, as a user of this database, should decide whether they represent widely used health interventions in your own setting.
Validity of estimate of measure of effectiveness The analysis of effectiveness was based on a randomised controlled trial for the first study sample. The analysis of the second sample may have lost some of the randomization benefits. The characteristics of those excluded for the second sample were not analysed. The randomisation process and the method of patient selection were not reported for the first sample. Selection bias may not be excluded and it was not clear whether the study sample was representative of the study population. The authors did not state whether some patients refused to participate in the study. It appears that sample size calculations were not performed and no evidence was provided that the initial study sample was appropriate. These issues may limit the internal validity of the analysis. However, some strengths of the analysis were the baseline comparability of the study groups for the first sample and the blind assessment performed over the follow-up period, although a longer follow-up period may have been useful.
Validity of estimate of measure of benefit No summary benefit measure was used in the economic analysis and no statistically significant differences were found in any of the clinical outcomes used in the effectiveness study. The analysis was therefore categorised as a cost-minimisation study (see validity of effectiveness comments above).
Validity of estimate of costs Overall, few details on the economic evaluation analysis were reported. The perspective adopted in the study was not stated and a detailed breakdown of costs was not provided. Unit costs were reported, but quantities of resources were not reported in detail. Costs and quantities were treated deterministically. No price year was reported, thus making reflation exercises in other settings difficult. Resource consumption was prospectively estimated alongside the clinical trial. The source of the cost estimates was not stated and there were no sensitivity analyses. You, as the reader, should decide if there are other related costs that would need to be measured fully to evaluate the two interventions.
Other issues The authors compared their findings with those from other studies, but only with respect to the effectiveness analysis. No comparison was made for the cost side of the analysis. The authors' report that the restenosis rates of this study agree with those previously reported for long coronary lesions. The authors did not address the issue of the generalisability of the study results to other settings and did not perform sensitivity analyses. As a consequence, the external validity of the analysis is somewhat limited. The study enrolled patients with long coronary lesions and this was reflected in the conclusions of the analysis, which should be considered valid only for this specific subgroup of patients suffering from symptomatic coronary artery disease. The authors noted that the length of the lesion was a risk factor for restenosis.
Implications of the study The study suggests that "the number of stents is not an independent factor for increasing the likelihood of restenosis, whereas the lesion length is the dominant factor". Thus one long stent could be safely and efficiently used for the treatment of patients with long coronary lesions.
Bibliographic details Hoffmann R, Herrmann G, Silber S, Braun P, Werner G S, Hennen B, Rupprecht H J, vom Dahl J, Hanrath P. Randomized comparison of success and adverse event rates and cost effectiveness of one long versus two short stents for treatment of long coronary narrowings. American Journal of Cardiology 2002; 90(5): 460-464 Indexing Status Subject indexing assigned by NLM MeSH Aged; Angioplasty, Balloon, Coronary /adverse effects /economics; Blood Vessel Prosthesis Implantation /adverse effects /economics; Coronary Angiography; Coronary Restenosis /etiology; Coronary Stenosis /economics /radiography /therapy; Cost-Benefit Analysis; Female; Follow-Up Studies; Hospitalization; Humans; Male; Middle Aged; Prospective Studies; Recurrence; Stents /adverse effects /economics; Time Factors; Treatment Outcome AccessionNumber 22002001654 Date bibliographic record published 31/07/2003 Date abstract record published 31/07/2003 |
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