New cost-effectiveness analysis supports limits on the use of drug-eluting stents

November 12, 2006

A cost-effectiveness analysis suggests that restricting the use of drug-eluting stents (DES) is prudent. In the analysis, the substitution of DES for bare metal stents appears to be cost-effective only when the target vessel revascularization (TVR) rate with bare metal stents is high, which is typically the case in small vessels and longer stenoses, said Sanjay Kaul, MD, MPH.

A cost-effectiveness analysis suggests that restricting the use of drug-eluting stents (DES) is prudent. In the analysis, the substitution of DES for bare metal stents appears to be cost-effective only when the target vessel revascularization (TVR) rate with bare metal stents is high, which is typically the case in small vessels and longer stenoses, said Sanjay Kaul, MD, MPH.

The purported cost superiority of DES over bare metal stents was derived on the basis of 2 pivotal clinical trials in the United States, which can be misleading, said Dr. Kaul. These reports of cost-effectiveness were based on model assumptions that are not consistent with "real-world" practice. For instance, the trials demonstrating cost-effectiveness of  DES assumed that 1.4 stents are used per case, that the TVR rate with bare metal stents is >12%, and that the rate of TVR with DES is reduced by 60%.

In reality, as exemplified by a real-world study known as BASKET (Basel Stent Kosten Effektivitäts Trial), 1.9 stents are used per case, the TVR rate with bare metal stents is 7.8%, and the reduction in TVR by DES is 41%.

In Dr. Kaul's analysis, he assumed that a DES costs $1,600 more than a bare metal stent, that either 1.5 or 2.0 stents were used per case, that the attributable cost of restenosis was $20,000, and that the definition of cost-effectiveness was $30,000 or less per TVR avoided.

Substituting a DES for a bare metal stent was cost-effective only when: 1) the risk of restenosis with a bare metal stent was high (a TVR rate >15%), which constitutes only about 20% of stent-eligible patients, and is typically observed in vessels smaller than 3 mm and stenoses longer than 15 mm, or 2) as "bail-out" use in patients who present with clinical restenosis following a bare metal stent, who represent about 10% to 15% of patients.

"The potential benefits of drug-eluting stents [have] been overestimated and the potential risks have been underestimated," said Dr. Kaul, the director of the vascular physiology and thrombosis research laboratory, Cedars-Sinai Medical Center, Los Angeles, Calif.

The analysis did not include the possibility of late clinical events due to stent thrombosis, a concern with DES that has been uncovered during the past year. "That aside, just to focus on efficacy and cost, we're making the point that drug-eluting stents are not as cost-effective as they were made out to be. When you add the antiplatelet therapy to offset the risk of stent thrombosis, the cost-effectiveness will be significantly diminished."

Dr. Kaul added: "If the risk associated with stent thrombosis resulting in clinical events is true, then it's moot to measure cost-effectiveness."