3 The technology
3.1 This appraisal is both a review of earlier NICE guidance (NICE Technology Appraisal Guidance No. 4; see Section 8) covering BMS, and a new appraisal of DES. BMS have already been described in Section 2 as part of existing practice. The rest of this section is devoted to methods of reducing restenosis and, in particular, to the use of DES as a means of achieving this.
3.2 Methods of reducing restenosis include: coating the stent with an appropriate drug; introducing an emitter of radioactive particles at the stenting site (brachytherapy); and creating the slow release of a drug from the stent, making the stent 'drug-eluting'. For DES, the drug is held temporarily in place within a polymer 'painted' onto the metallic stent. Other than one trial (the ELUTES trial), there is little evidence in favour of coating the stent directly with an active drug (without a polymer); this technology, and brachytherapy, are outside the scope of this appraisal.
3.3 Although a number of drugs have been tested in the context of DES, only three have been granted CE (Conformite Europeene) marking for use within EU countries: paclitaxel, which inhibits cell division, elutes from the Taxus stent; sirolimus (previously known as rapamycin), an immunosuppressive agent that reduces inflammation, elutes from the Cypher stent; and dexamethasone, a synthetic adrenocortical steroid that reduces inflammation, elutes from the BiodivYsio stent. These drugs may elute at different rates, depending on the presence or absence of additional polymer coatings on the stent. Because the performance of a DES depends critically on the particular drug being used, each DES should be regarded as a separate technology. However, as yet, studies directly comparing different DES have not been performed.
3.4 Both types of stent (BMS and DES) require the use of an antiplatelet drug in addition to aspirin. Such drugs should be used after the implantation of a stent, in accordance with the device-specific instructions for use (IFU).
3.5 List prices for both BMS and DES differ between manufacturers, and some manufacturers produce more than one stent in each class, at different prices. Prices for BMS range from about £600 to £900 and for DES from about £1300 to £1500 per stent. For bare-metal and drug-eluting stents that are the same apart from their drug-eluting properties, the difference in cost is about £500 to £600. Costs may vary in different settings because of negotiated procurement discounts.