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Resource utilization and clinical outcomes of coronary stenting: a comparison of intravascular ultrasound and angiographical guided stent implantation |
Choi J W, Goodreau L M, Davidson C 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 Intravascular ultrasound (IVUS)-guided coronary stent implantation was compared with angiographically-guided stent implantation. The treated vessel was imaged with a 30-MHz 2.9 F or 3.2 F mechanically-rotated intravascular ultrasound transducer (Boston Scientific/Cardovascular Imaging Systems).
Economic study type Cost-effectiveness analysis.
Study population The study population consisted of patients with symptomatic coronary artery disease, who underwent elective and emergency coronary artery stenting of a single native coronary vessel. Patients receiving stent implantations of saphenous vein grafts or multiple vessels were excluded.
Setting The setting was secondary care. The economic study was conducted at North Western University Medical School, Chicago, USA.
Dates to which data relate The effectiveness evidence and resource use data were gathered from January 1997 to January 1998. The price year was not stated.
Source of effectiveness data The effectiveness data were derived from a single study
Link between effectiveness and cost data Both the effectiveness and resource use data were established retrospectively on the same sample.
Study sample No power calculations to determine the sample size were reported. All those who matched the criteria for study population were included. The total number of participants in the study was 278, of which 178 were in the IVUS-guided group (intervention) and 100 in the angiographically-guided group (control).
Study design This was a single-centred retrospective cohort study. The duration of follow-up was 6 months. Data were available for 174 (94%) patients in the intervention group and 94 (94%) patients in the control group. No reasons for withdrawal were reported. Two experienced angiographers, who were blinded to the clinical outcomes and use of IVUS, reviewed coronary angiograms.
Analysis of effectiveness The clinical study was analysed on the basis of treatment completers only. Each patient's angiogram was evaluated for percentage stenosis, lesion length, presence of thrombus, final percentage of stenosis, side branch occlusion, thrombus formation, dissection, distal embolisation, perforation, use of abciximab, or adjunctive atherectomy. Major adverse cardiac events (MACE) were defined as repeat percutaneous transluminal coronary angioplasty, coronary artery bypass surgery, subsequent myocardial infarction, or cardiac death. The demographic characteristics of the groups were provided in the paper. The authors reported no important differences between the groups. The lesion characteristics of the IVUS-guided and angiographically-guided groups were similar. There was no difference in the number of native coronary arteries with significant coronary artery disease (stenosis greater than 50%), target vessel, lesion length, initial Thrombolysis in Myocardial Infarction (TIMI) flow, and presence of thrombus. Likewise, many of the procedural variables between the respective groups were similar.
Effectiveness results The overall MACE rate was 19% for the angiographic group and 12% for the IVUS group, (p=0.11).
Of all the clinical outcomes considered in the study, only in-hospital abrupt closure was statistically significant. There was one patient (0.6%) in the IVUS group and 4 patients (4%) in the control group, (p=0.04).
In the univariate analysis, the relative risk ratios for TIMI flow (1.44, 95% confidence interval, CI: 1.01 - 2.06; p=0.05), maximum balloon size (0.34, 95% CI: 0.13 - 0.88; p=0.03) and last balloon size (0.29, 95% CI: 0.12 - 0.69; p=0.005) were significant.
Multivariate analysis demonstrated, according to the authors, that IVUS use was an independent negative predictor of MACE (relative risk ratio 0.49, 95% CI: 0.25 - 0.98; p=0.04).
Clinical conclusions The use of IVUS guidance during stent implantation is associated with a significant decrease in the in-hospital abrupt closure rate. It is also associated with a trend towards a lower 6-month target vessel revascularisation rate.
Modelling Logistic regression analysis was performed to assess the demographic, lesion and procedural characteristics associated with abrupt closure, cardiac death, subsequent myocardial infarction, or repeat revascularisation.
Measure of benefits used in the economic analysis No summary measure of health benefit was used. A cost-consequences analysis was therefore performed.
Direct costs The quantities and the prices were stated separately. The costs were estimated from actual data. The resources used in the cost analysis included procedure time, fluoroscopy exposure time, contrast volume, number of guidewires, guide catheters, stents and balloons. If a second procedure was necessary during the index hospitalisation, due to abrupt vessel closure, the repeat procedure cost was added to the original procedural costs. Post-procedure hospital costs, blood laboratory studies, medication fees and physician fees were not included in the cost analysis. The price sources and dates for resource use were not stated. No discounting was carried out, which was appropriate as the total duration of the study was less than 2 years. The study reported average resource utilisation and average total procedural cost, with standard deviations (SDs).
Statistical analysis of costs Resource utilisation was treated stochastically. The mean values, SD and P-values were reported for quantities, and for the total procedural cost only. Continuous variables were compared using the t-test, although the authors did not justify its use for the cost data.
Indirect Costs No indirect costs were included.
Sensitivity analysis No sensitivity analysis was carried out on the costs.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section.
Cost results The total procedural cost was $4,142 (SD=1,547) for the IVUS-guided group, compared with $3,636 (SD=1,949) for the angiographically-guided group, (p=0.03).
Within the IVUS-guided group, patients with additional interventions after IVUS imaging had average procedural costs of $4,648 (SD=1,533) versus $3,683 (SD=1,383) for patients who did not required additional interventions, (p=0.0001).
Synthesis of costs and benefits Authors' conclusions Despite the use of intravascular ultrasound (IVUS), guided stent implantation is associated with a significant increase in costs. It is also associated with a significant decrease in the in-hospital abrupt closure rate and a trend towards a lower 6-month target vessel revascularisation rate.
CRD COMMENTARY - Selection of comparators Although no explicit justification was given for the comparator used, it would appear to represent current practice in the authors' setting. You should decide if the comparator represents current practice in your own setting.
Validity of estimate of measure of effectiveness The analysis used a retrospective study, which was appropriate for the study question, but may be associated with bias. The study sample was representative of the study population and the patient groups seem to have been comparable. No statistical analysis was undertaken to take account of possible biases or confounding factors. The authors recognise that the lack of significant differences in their effectiveness results could be due to the small sample size.
Validity of estimate of measure of benefit The authors did not derive a summary measure of health benefits. The analysis was therefore categorised as a cost-consequences analysis.
Validity of estimate of costs It is unclear whether all the categories of cost relevant to the perspective adopted have been included in the analysis. There was no information about what was included in the item "procedural cost" (table III of the paper). However, the costs and the quantities were reported separately, although not for all the cost items included in the study. Statistical analysis of resources was performed, but no information about the sources of the prices was provided. Discounting was not performed, which was appropriate since the data were collected in only one year.
Other issues The authors made appropriate comparisons of their findings with those from other studies. The issue of generalisability to other settings was not addressed. The authors reported other limitations of the study, such as possible selection bias in the use of IVUS guidance.
Implications of the study The use of IVUS guidance during stent implantation does not significantly increase procedure time, fluoroscopy exposure, contrast volume, or device utilisation. Further, despite the increase in procedural cost, IVUS-guided stent implantation is associated with a significant decrease in the in-hospital abrupt closure rate and a trend towards a lower 6-month target vessel revascularisation.
Bibliographic details Choi J W, Goodreau L M, Davidson C J. Resource utilization and clinical outcomes of coronary stenting: a comparison of intravascular ultrasound and angiographical guided stent implantation. American Heart Journal 2001; 142(1): 112-118 Other publications of related interest Mudra H, Macaya C, Zahn R, et al. Interim analysis of the "OPTimization with ICUS to reduce stent restenosis" (OPTICUS) trial. Circulation 1998;98 Suppl I:1363.
Indexing Status Subject indexing assigned by NLM MeSH Aged; Chi-Square Distribution; Coronary Angiography /economics; Coronary Disease /radiography /therapy /ultrasonography; Female; Humans; Logistic Models; Male; Middle Aged; Recurrence; Retrospective Studies; Stents /economics; Treatment Outcome; Ultrasonography, Interventional /economics AccessionNumber 22001001386 Date bibliographic record published 31/07/2003 Date abstract record published 31/07/2003 |
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