Drug-eluting stents: from evidence to policy

Drug-eluting stents are a major breakthrough in cardiology, with the Cypher (Cordis Corporation) and Taxus (Boston Scientific) stents preventing 60-70% of repeat coronary revascularizations, compared with bare metal stents. Both evidence- and risk-based application of drug-eluting stents is expected to create relevant financial and equity problems to most public hospitals, as the cost of drug-eluting stents is over 1000 higher than traditional stents. In the perspective of third-party payers, drug-eluting stents are cost-effective revascularization strategies for a large portion of patients actually undergoing stenting. However, adequate guidelines and reimbursement strategies are still awaited in several countries.

Poly(ethylene carbonate): A thermoelastic and biodegradable biomaterial for drug eluting stent coatings?

A first feasibility study exploring the utility of poly(ethylene carbonate) (PEC) as coating material for drug eluting stents under in vitro conditions is reported. PEC (Mw 242 kDa, Mw/Mn=1.90) was found to be an amorphous polymer with thermoelastic properties. Tensile testing revealed a stress to strain failure of more than 600%. These properties are thought to be advantageous for expanding coated stents. In vitro cytotoxicity tests showed excellent cytocompatibility of PEC. Based on these findings, a new stenting concept was suggested, pre-coating a bare-metal stent with PPX-N as non-biodegradable basis and applying a secondary PEC coating using an airbrush method. After manual expansion, no delamination or destruction of the coating could be observed using scanning electron microscopy. The surface degradation-controlled release mechanism of PEC may provide the basis for "on demand" drug eluting stent coatings, releasing an incorporated drug predominantly at an inflamed implantation site upon direct contact with superoxide-releasing macrophages. As a release model, metal plates of a defined size and area were coated under the same conditions as the stents with PEC containing radiolabelled paclitaxel. An alkaline KO(2-) solution served as a superoxide source. Within 12 h, 100% of the incorporated paclitaxel was released, while only 20% of the drug was released in non-superoxide releasing control buffer within 3 weeks.

Cost-effectiveness of drug-eluting coronary stents in Quebec, Canada

Objectives:The aim of this investigation was to assess the incremental cost-effectiveness of replacing bare metal coronary stents (BMS) with drug-eluting stents (DES) in the Province of Quebec, Canada.

Methods:The strategy used was a cost-effectiveness analysis from the perspective of the health-care provider, in the province of Quebec, Canada (population 7.5 million). The main outcome measure was the cost per avoided revascularization intervention.

Results:Based on the annual Quebec rate of 14,000 angioplasties with an average of 1.7 stents per procedure and a purchase cost of $2,600 Canadian dollar (CDN) for DES, 100 percent substitution of BMS with DES would require an additional $45.1 million CDN of funding. After the benefits of reduced repeat revascularization interventions are included, the incremental cost would be $35.2 million CDN. The cost per avoided revascularization intervention (18 percent coronary artery bypass graft, 82 percent percutaneous coronary intervention [PCI]) would be $23,067 CDN. If DES were offered selectively to higher risk populations, for example, a 20 percent subgroup with a relative restenosis risk of 2.5 times the current bare metal rate, the incremental cost of the program would be $4.9 million CDN at a cost of $7,800 per avoided revascularization procedure. Break-even costs for the program would occur at DES purchase cost of $1,161 for 100 percent DES use and $1,627 for selective 20 percent DES use for high-risk patients for restenosis (RR = 2.5). Univariate and Monte Carlo sensitivity analyses indicate that the parameters most affecting the analysis are the capacity to select patients at high risk of restenosis, the average number of stents used per PCI, baseline restenosis rates for BMS, the effectiveness ratio of restenosis prevention for DES versus BMS, the cost of DES, and the revascularization rate after initial PCI. Sensitivity analyses suggest little additional health benefits but escalating cost-effectiveness ratios once a DES penetration of 40 percent has been attained.

Conclusions:Under current conditions in Quebec, Canada, selective use of DES in high-risk patients is the most acceptable strategy in terms of cost-effectiveness. Results of such an analysis would be expected to be similar in other countries with key model parameters similar to those used in this model. This model provides an example of how to evaluate the cost-effectiveness of selective use of a new technology in high-risk patients.

What reimbursement for coronary revascularization with drug-eluting stents?

We investigated the clinical and economic impact of sirolimus-eluting coronary stents (SES) at a nationwide level as to advice about the feasible reimbursement policy for the Italian Health Care System (SSN). A decision model compared bare metal stents (BMS) and SES in terms of costs and repeat coronary revascularizations incurred in 12 months following the first revascularization. The model was compiled for eight subgroups of patients. Rates of events were derived from randomized trials and an 1,809-patient survey. National charges were used to evaluate resources consumption. Compared with BMS, the number of averted revascularizations with SES is 0.16 per patient. SES also save Euro 1,371 per patient. Total savings to SSN are proportional to the rate of SES adoption by Italian hospitals: assuming a complete replacement of BMS with SES, the model estimates that 7,095 revascularizations would be averted and more than Euro 60 million saved by the SSN in 1 year. To stimulate SES adoption a SES-specific DRG might by introduced with a reimbursement value 23% higher than the current charge. SES is thus a cost-saving strategy in the perspective of the SSN that could therefore support the introduction of the new technology by reimbursing about 80% of its current incremental acquisition cost.

Drug-eluting stents and glycoprotein IIb/IIIa inhibitors: combination therapy for the future

BACKGROUND

Although coronary stenting has improved the results of coronary interventions compared to coronary angioplasty alone, in-stent restenosis remains a significant limitation of this procedure. Drug-eluting stents with or without glycoprotein IIb/IIIa inhibitor therapy represent an additional advance in the evolution of this strategy.

METHODS

We review the currently available trials comparing studies of non-drug-eluting and drug-eluting stents using sirolimus and paclitaxel agents and their derivatives.

RESULTS

Ten studies are available that compare drug-eluting to traditional non-drug-eluting stents. A variety of antiplatelet regimes have been used. The majority of these studies are in the process of being published. No head-to-head studies comparing different drug-eluting stents are available.

CONCLUSIONS

Drug-eluting stents using sirolimus and paclitaxel in combination with enhanced antiplatelet strategies represent an important advantage over non-drug-eluting stents for the reduction of in-stent restenosis. The rate at which drug-eluting stents are adapted into widespread practice depends heavily on whether they are safe, efficacious, and cost-effective in various clinical settings.