European Heart Journal Advance Access originally published online on November 17, 2006
European Heart Journal 2006 27(24):2996-3003; doi:10.1093/eurheartj/ehl357
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Cost-effectiveness of the unrestricted use of sirolimus-eluting stents vs. bare metal stents at 1 and 2-year follow-up: results from the RESEARCH Registry
Thoraxcenter, Erasmus Medical Center, Ba-583, Dr Molewaterplein 40, 3015 GD Rotterdam, The Netherlands
Received 12 January 2006; revised 6 October 2006; accepted 12 October 2006; online publish-ahead-of-print 17 November 2006.
* Corresponding author. Tel: +31 10 463 5260; fax: +31 10 436 9154. E-mail address: p.w.j.c.serruys{at}erasmusmc.nl
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Abstract |
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Aims To assess the cost-effectiveness of sirolimus-eluting stents (SESs) compared with bare metal stents (BMSs) as the default strategy in unselected patients treated in the Rapamycin Eluting Stent Evaluated At Rotterdam Cardiology Hospital (RESEARCH) Registry at 1 and 2-years following the procedure.
Methods and results A total of 508 consecutive patients with de novo lesions exclusively treated with SES were compared with 450 patients treated with BMS from the immediate preceding period. Resource use and costs of the index procedure, and clinical outcomes were prospectively recorded over a 2-year follow-up period. Follow-up costs were measured as unit costs per patient based on the incidence of clinically driven target vessel revascularization (TVR), to obtain cumulative costs at 1 and 2-years. Cost-effectiveness was measured as the incremental cost-effectiveness ratio (ICER) per TVR avoided.
The use of SES cost 
3036 more per patient at the index procedure, driven by the price of SES. Follow-up costs after 1-year were 1,089 less with SES when compared with BMS, due to less TVR, resulting in a net excess cost of 1968 per patient in the SES group, and reduced by a further 100 per patient in the second year. The incidence of death or myocardial infarction between groups was similar at 1 and 2 years. Rates of TVR in the SES and BMS groups were 3.7% vs. 10.4%, P<0.01 at 1 year, respectively; and 6.4% vs. 14.7%, P<0.001 at 2 years. The ICER per TVR avoided was 29 373 at 1 year, and 22 267 at 2 years.
Conclusion The use of SES, while significantly beneficial in reducing the need for repeat revascularization, was more expensive and not cost-effective in the RESEARCH registry at either 1 or 2-years when compared with BMS. On the basis of these results, in an unselected population with 1 year of follow-up, the unit price of SES would have to be 1023 in order to be cost-neutral.
Key Words: Cost-effectiveness • Drug-eluting stents • Sirolimus • Real-world • Registry
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Introduction |
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Drug-eluting stents have revolutionized the treatment of coronary artery stenosis by systemically reducing the need for re-intervention following stent implantation.1 The pivotal European randomized trial comparing sirolimus-eluting stents (SESs) with bare metal stents (BMSs), RAVEL,2 paved the way for the definitive trial, SIRIUS,3 conducted in the United States. These respective trials led to its commercialization in Europe in 2002 and in the United States in 2003. Confirmation of the efficacy of SES over BMSs in a diverse unselected population was made in the Rapamycin Eluting Stent Evaluated At Rotterdam Cardiology Hospital (RESEARCH) Registry with 14 and 2-year follow-up.5 More recently, the randomized BASKET trial with 6 months follow-up concurred with the results of RESEARCH.6
The market price of drug-eluting stents has almost unanimously been perceived as the major limitation for a more widespread use of SES worldwide.7 On the other hand, the striking decrease in the incidence of cardiac events with the use of SES is theoretically associated with a reduction in resource utilization, and therefore costs, during follow-up. In the RAVEL trial, the treatment of a single native de novo coronary lesion with SES was associated with an increased procedural cost of 1286 over BMS, which was reduced to an additional cost of 54 after 1 year of follow-up, mainly because of the lower frequency of repeat revascularizations among SES-treated patients.8 Correspondingly, in the SIRIUS randomized trial, patients treated with SES cost US$2881 more than BMS patients. At 1 year, aggregate costs narrowed but were still US$ 309 higher in SES patients.9 The incremental cost-effectiveness ratio (ICER) for SES was US$1650 per repeat revascularization avoided.
Although the cost-effectiveness profile of SES has been assessed in the context of randomized trials,8,9 there is limited information on the balance between costs and effects of SES in the real world. In the present study, we performed a prospective resource utilization and economic evaluation during a 2-year follow-up period of the patients treated in the RESEARCH registry.
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Methods |
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Patient population and treatment strategy
The RESEARCH registry is a single-centre registry conducted with the main purpose of evaluating the safety and efficacy of SES implantation for patients treated in daily practice. Its study design has been previously published.10 Briefly, since 16 April 2002, our institution has adopted a policy of using SES (Cypher; Johnson & Johnson-Cordis unit, Cordis Europa, NV, USA) as the default stent for every percutaneous coronary intervention. In the first 6 months of enrolment, 508 patients with de novo lesions were treated exclusively with SES (SES group) and compared with a group of 450 consecutive patients treated with BMS for de novo lesions in the preceding 6 months (pre-SES group). The total study population thus comprised 958 patients divided into two sequential cohorts, primarily distinguished by the interventional strategy applied (BMS or SES implantation, respectively). This protocol was approved by the hospital Ethics Committee and is in accordance with the Declaration of Helsinki. Written informed consent was obtained from every patient.
All interventions were performed according to current standard guidelines with the final interventional strategy (including use of periprocedural glycoprotein IIb/IIIa inhibitors) at the operator's discretion. All patients were advised to maintain lifelong aspirin. At least 1-month clopidogrel treatment (75 mg/d) was recommended for patients treated in the pre-SES phase. For patients treated with SES, clopidogrel was prescribed for at least 3 months, unless one of the following was present (in which case clopidogrel was maintained for at least 6 months): multiple SES implantation (>3 stents), total stented length >36 mm, chronic total occlusion, and bifurcations.
Determination of costs
For each index procedure, detailed resource use and costs were recorded on a dedicated electronic database, together with the actual costs for 2001 and 2002 and calculated on the basis of equipment opened during the angioplasty, irrespective of its actual use in the patient. With respect to costs, the analysis was limited to direct medical costs. The actual price paid for per SES was 1929 euros, while the average weighted price of a bare stent in the study period was 692. Medication costs were obtained for glycoprotein IIb/IIIa inhibitors and contrast, while for the others, a reasonable assumption of 150 per patient was made to cover the costs of other intra-procedural medications (e.g. heparin, nitrates, saline, beta-blockers, etc.). The cost of post-procedural clopidogrel in both groups was calculated on the basis of duration of prescription determined at the completion of the index procedure.
Lengths of hospital stay were calculated by querying the hospital's admission and discharge database, which records the date of admission and discharge, into and out of individual wards. Consequently, admissions to a particular type of ward are considered on a per day basis. As this hospital is a tertiary referral centre, the majority of discharges are to referring or peripheral hospitals. Length of stay was calculated from the time of the procedure up to the point of discharge from this hospital. Unit costs were estimated on the basis of detailed information from our institution following an approach similar to that reported previously.8
Follow-up costs were estimated according to the need for repeat revascularization. As the incidence of death and myocardial infarction (MI) between both groups did not differ, they were not costed.4,5 A re-intervention was defined as any target-vessel revascularization (TVR) (percutaneous or surgical). Costs of re-intervention were estimated as the product of the event multiplied by the cost per event taken from the RAVEL study, adjusted for inflation.11 The costs of outpatient visits, related work-up, and other ongoing medications were not tracked.
Determination of effectiveness and cost-effectiveness analysis
Major adverse cardiac events were defined as (1) death, (2) non-fatal MI, or (3) TVR. An MI was diagnosed by a rise in the creatine kinase-MB fraction of more than three times the upper limit of normal. A TVR was defined as a repeat intervention (surgical or percutaneous) driven by any lesion located in the same epicardial vessel(s) as the treated lesion(s). The results of both the 1 and 2-year clinical follow-up have been published.4,5
For the purposes of the cost-effectiveness analysis, the following assumptions were required. The incidence of repeat revascularization is given as whole numbers and the proportion estimated according to the Kaplan–Meier method. There were a disproportionate number of post-procedural coronary angiograms performed in the SES period, due to the repeat angiography mandated in ‘complex’ patients, typically with SES implanted in bifurcations, left main coronary, chronic total occlusions, very small vessels, long stented length (>36 mm), and acute MI.4 Because of the well-known effect of angiographic re-evaluation in increasing the incidence of repeat revascularization,12 all re-interventions in the first year were retrospectively adjudicated and classified as clinically driven or non-clinically driven by a group of clinicians not involved in the treatment of the particular patient analysed.4 Clinically driven repeat revascularizations were defined as any intervention motivated by a significant luminal stenosis (>50% diameter stenosis) in the presence of anginal symptoms and/or proven myocardial ischaemia in the target-vessel territory by non-invasive testing. No mandated angiographic re-study was performed in the pre-SES group.
In order to correct for the excess additional costs related to the mandatory angiographic studies in the SES group, it was assumed that the actual number of clinically driven restudies would be proportionate to the number of clinically driven re-interventions. Therefore, the number of patients that would have had clinically driven angiography could be calculated from the figures found in the pre-SES phase. As clinically driven re-interventions in the SES phase were less frequent than in the pre-SES by a factor of 0.356, the number of patients who would have undergone clinically driven re-study in the absence of mandatory angiographic follow-up was calculated as 0.356x proportion of patients in pre-SES group with angiographyxnumber of patients in SES group. From this, it was estimated that 24 patients would have had a re-study in the SES group.
Statistical analysis
Continuous variables are presented as mean±SD and were compared by means of the Student unpaired t-test. Categorical variables are presented as counts and percentages and compared by means of the Fisher exact test. Resource use is reported on a per patient basis. Cost data are reported as both mean and median values and compared by t-tests. All statistical and cost-effectiveness analysis were performed on an intention-to-treat principle. All statistical tests were two-tailed.
The uncertainty surrounding the differences in costs and effects were estimated using the bootstrapping technique. With bootstrapping, average costs and effects were repeated 1000 times. Each bootstrap provides a new estimate of average costs and average effects with the resulting 1000 estimates summarized in terms of a distribution. Truncating the upper and lower 2.5% of the distribution provides the 95% confidence intervals which are then demonstrated visually. This is a useful method when the distribution cannot be obtained in a classic way.13 Furthermore, additional graphical representation of the bootstrapping results are presented with 5%, 50%, and 95% probability ellipses, to describe their degree of uncertainty.
Cost-effectiveness was measured as the ICER per repeat revascularization avoided. It is obtained by dividing the difference in medical costs expended by our institution at the end of one and 2 years for the two treatment groups by the difference in repeat revascularization rates over the same time frames.9
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Results |
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Baseline and procedural characteristics
The RESEARCH registry was a real-world study into drug-eluting stent use, and enrolled all-comers. The baseline and procedural characteristics in Table 1 reflect the complex patient demographics typically seen in a tertiary referral centre for PCI. Both groups were reasonably well matched for baseline characteristics, with the exception of previous MI being more common in the pre-SES group. Over half of the patients presented with an acute coronary syndrome, and an acute MI was the reason for intervention in 18% of patients.
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Major adverse cardiac events
The 1 and 2-year results of the RESEARCH registry have been published.4,5 Briefly, the combined outcome of death or MI was similar and the difference in major adverse cardiac events was driven by the reduction in the need for repeat revascularization, defined as TVR in the SES group. Similarly, at 2 years, the reduction in major adverse cardiac events was again due to the reduction in TVR in the SES group.
At the end of 1 year, less patients underwent a re-intervention procedure in the SES group (3.65% in the SES group as compared with 10.4% in the pre-SES group, P<0.001; Table 4, Figure 1). During the first year of follow-up, because of mandated angiographic re-study, significantly more patients underwent coronary angiography in the SES period compared with the BMS period, 175 vs. 59, P<0.001). At 2 years, the difference in re-intervention rates widened from 6.75 to 8.3%. (a cumulative incidence of 6.4 vs. 14.7% respectively, P<0.001).
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Resource use at index procedure
The procedural equipment use is listed in Table 2 with the results expressed as mean number of items consumed per patient. On a per patient basis, significantly more guiding catheters, coronary wires, balloons, and contrast were used, and more stents were implanted resulting in a longer procedural time in the SES phase compared with the pre-SES phase. This reflects the increased complexity of cases seen in the SES phase. Post-procedurally, total in-hospital stay at our institution was similar, 2.6 days in the pre-SES phase and 2.0 days in the SES group, P=0.15.
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Costs of index procedure
The overall average per patient cost of the index procedure was
6887 in the pre-SES group and 9924 in the SES group, an excess of 3036 in the SES group (Table 3), driven by the difference of 2925 due to the price premium of SES.
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Costs at follow-up
At 1-year follow-up, the difference in costs had narrowed from
3036 to 1968 due to the reduction in re-interventions (Table 4). At the end of 2 years following the index procedure, this difference further narrowed to 1869, due to a non-significantly fewer number of events in the SES group in the second year of follow-up.
Cost effectiveness
Figures 2 and 3 depict the estimated differences in costs and effectiveness of SES vs. BMS, at 1 and 2 years. All estimates lie in the right-upper quadrant, indicating that SES are clearly more effective but also more costly than BMS. Note that the ellipse in Figure 4 is shifted downwards and outwards in the 2-year follow-up, as compared with the 1-year follow-up, although not significantly.
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On the basis of costs and results obtained from the RESEARCH registry, the ICER was then calculated. In the 1-year analysis, the ICER for SES was calculated at
29 373 per repeat revascularization avoided; while at the end of 2 years, this number had decreased to 22 627 per repeat revascularization avoided (Table 4).
From this ratio, a straight-line relationship exists between the unit price of a new device vs. the ICER at a given unit price of the old device (Figure 4). Thus, at a price of 692 per bare stent for the bare stent group (the actual average weighted price of BMSs in this registry), the calculated cost neutral price for the DES would be 1023 with the 1-year result of this registry, while at the maximum acceptable threshold of 10 000 per repeat revascularization avoided,9 the highest price would be 1336 per DES. At 2 years, the cost neutral price and the cost at the 10 000 threshold declined slightly (1069 and 1452, respectively) due to the non-significant reduction in events in the second year.
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Discussion |
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The primary finding of this analysis of the RESEARCH registry is that based on the price of
1929 per SES paid by our institution in April 2002, the unrestricted use of SES was not cost-effective to our institution, at either 1 or 2 years, using the acceptable maximum threshold of 10 000 per repeat revascularization avoided. Using 1-year costs and effects, the calculated cost-neutral price for SES was 1023; while at the acceptable threshold of 10 000 per repeat revascularization avoided, the calculated price was 1336 per SES. With the inclusion of second year costs, in association with a further non-significant reduction in events in the second year, the cost neutral price was 1069 or 1452 at the 10 000 threshold.
Specific features of this study
As a tertiary referral centre with a feeder population of 14 peripheral hospitals, our institution has a policy of returning stable patients to their referral hospital or to the hospital in their catchment area. Unstable patients and patients from our catchment area are treated at our institution until such time that they are suitable for discharge home or discharge to their local hospital. In the combined population, only 4.1% of patients were admitted for longer than 10 days at our institution.
The introduction of SES in the second period of the RESEARCH registry created a real-world imbalance. Despite similar presenting symptoms and clinical characteristics, more segments were treated, resulting in longer stented lengths and the use of more stents. Although this resulted in higher costs to the SES group, it reflects daily practice outside of clinical trials, where the introduction of DES has resulted in the implantation of more stents. Furthermore, the ongoing use of DES at our institution resulted in the treatment of more complex patients, with even longer stented lengths implanted in the following year.14
Costs outside randomized trials
Cost-effectiveness studies from the randomized RAVEL and SIRIUS trials have been published. In both these studies, use of SES resulted in additional 1-year costs of 166 and US$309 in the SES groups, respectively (NB 1
US$1.30 April 2005). The additional cost of DES was effectively negated by the decreased follow-up costs resulting from a decrease in the need for repeat intervention. In this present study, the reduction in follow-up costs were insufficient to compensate for the elevated index cost, when measured at the end of either 1 or 2 years. The respective excess cost in the SES group were 1968 and 1869, respectively, much higher than that reported from the randomized trials. This reflects the results of DES use outside of trials.
Acceptable cost of DES outside randomized trials
The results of RAVEL and SIRIUS would suggest that the prices of DES of 2000 and US$2900 are reasonably cost-effective. At the time this registry was conducted, the price of DES paid for by our institution was 1929 while the price of bare stents was 692, reflecting the prices of April 2002. Since that time, paclitaxel-eluting stents (Boston Scientific Corporation) have been introduced, and zotarolimus-eluting stents (Medtronic Corporation) have recently received CE mark certification. This increased competition, together with an increasing market share of DES, will serve to bring down prices of DES to that judged as cost-effective in our model. Correspondingly, as the market share of BMSs shrink, their prices will also fall, thus necessitating that the price of DES fall even further than that predicted. Given a not unreasonable bare stent price of 400 today, a DES would have to fall to 779 to be cost-neutral within the framework of the model presented here.
Comparison with other ‘real-world’ trials
The BASKET ‘real-world’ randomized study demonstrated that at 6 months, DES were on average, 905 more expensive per patient when compared with BMS. In that study, the price difference between DES and BMS were considerably less than in this study, resulting in a calculated ICER of less than 20 000 per major event avoided, as opposed to the 29 373 at 1 year, and 22 627 at 2 years per repeat revascularization avoided in our series. Despite the smaller difference, the results of the present study are in concordance with their findings, and has the advantage of extended follow-up out to 2 years.
Implications of prolonged follow-up
A specific feature of this report is the prolonged follow-up out to 2 years. The non-significant widening of the treatment effect from the first to the second year resulted in lowering of the ICER by almost 7000, but not sufficient to make the finding cost-effective. It remains to be seen if prolonged follow-up out to 5 years will equalize the groups, however, most cost-effectiveness studies are generally limited to short-term follow-ups of 1 year.
Applicability to other drug-eluting stent systems and to newer bare-stent systems
This study was a specific comparison between SES and BMS, and since both pricing and efficacy of the different DES systems in the market today vary, the results of this study may not be totally generalizable to other systems. However, given the ongoing price premium and better outcomes of DES, this study may therefore be used as a guide. Similarly, there are now newer generation BMS, such as those incorporating non-drug-eluting coatings (e.g. carbon-, titanium oxide-, and CD34 antibody-coated stents),15,16 which have demonstrated better restenosis rates than conventional BMS used in this study and consequently, the possibility exists that the differential benefit of DES may be reduced when compared against these newer BMS devices.
Limitations
By design, the costs in this study specifically reflect procedural and follow-up costs directly impacting on our institution. It is therefore an institutional as opposed to a societal analysis, and therefore underestimates the true overall societal cost by not accounting for total length of stay in other hospitals nor costs associated with follow-up visits and work-up for recurrent symptoms. This was a necessary limitation, given the tertiary referral nature of our practice and the multiple complex co-morbidities seen in this ‘real-world’ population.
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Conclusion |
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The lower differential effect in real-world outcomes, together with increased material use compared with randomized trials combine to reduce the cost-effectiveness of SESs compared with BMSs. On the basis of our findings, prices of SES need to be further reduced in order to become cost-effective.
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Acknowledgements |
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This study was supported by the Erasmus MC, Rotterdam, and by an unrestricted institutional grant from Cordis, a Johnson and Johnson company.
Conflict of interest: no conflict of interest.
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Footnotes |
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The results reported in this manuscript have been presented in part at the EuroPCR 2005 Meeting, May 2005, Paris, France. 
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