Study Takes Clopidogrel into Account in Assessing DES Cost-Effectiveness

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Over 3-year follow-up, the higher upfront cost of drug-eluting stents (DES) compared with bare-metal stents (BMS) is offset by reduced need for target vessel revascularization (TVR). In addition, even when the need for prolonged dual antiplatelet therapy is factored in, DES remain reasonably cost-effective, according to a single-center study published online June 21, 2011, ahead of print in Circulation: Cardiovascular Quality and Outcomes.

To evaluate the real-world cost of stenting, Robert J. Applegate, MD, of the Wake Forest University School of Medicine (Winston-Salem, NC), and colleagues gathered data on clinical outcomes and costs of care for 1,147 patients implanted with BMS in 2002 and 2003 and 1,247 who received DES in 2004 and 2005, a period when the newer devices were fully available and accounted for 90% of all PCI procedures at Wake Forest Medical Center. Patients receiving BMS during the DES era were excluded to minimize selection bias.

Clopidogrel Adds to Expenses

Baseline clinical and procedural characteristics were well matched between the 2 groups, with 72% of DES and 70% of BMS patients presenting with ACS. Exceptions were longer mean stent length with DES (24.8 ± 8.0 mm vs. 20.1 ± 99 mm with BMS; P < 0.001) and somewhat higher in-laboratory use of bivalirudin with DES (13% vs. 9% with BMS; P = 0.002).

At the 3-year landmark, 31% of DES patients and 25% of BMS patients were on clopidogrel therapy (P < 0.001). Cumulative mean clopidogrel durations over the entire study period were 499 days for DES and 329 days for BMS (P < 0.001).

Clinical outcomes were generally more favorable for DES than for BMS at 3-year follow-up, including a 32% reduction in the need for TVR and 29% reduction in all-cause death. Stent thrombosis rates were similar for both groups (table 1).

Table 1. Cumulative 3-Year Outcomes

Index stenting costs were higher per patient treated with DES vs. BMS, as was the cost of clopidogrel therapy after treatment. However, the higher need for repeat revascularization over follow-up increased costs for BMS. By 3 years, total costs were statistically similar regardless of the device type used (table 2).

Table 2. Mean 3-Year Costs

Based on these findings, the cost of each TVR avoided with DES use was $4,731 through 1 year, $4,703 through 2 years, and $6,379 through 3 years. Notably, calculations of cost-effectiveness fell within a threshold of $10,000 for all 3 time points.

A secondary analysis intended to gauge the influence of TVR on quality and duration of life was less positive towards DES. The investigators calculated that, per quality-adjusted life-year (QALY) gained, DES cost $65,052 through 1 year, $63,426 through 2 years, and $87,705 through 3 years.

In a telephone interview with TCTMD, Ajay J. Kirtane, MD, SM, of Columbia University Medical Center (New York, NY), pointed out that the typical cutoff for cost-effectiveness when considering QALY gained is $50,000.

Measuring Real-World Impact

“These observations provide some of the first insights into the cost-effectiveness of DES compared with BMS in routine clinical practice and highlight the importance of prolonged dual antiplatelet use in this setting,” the investigators note, adding that previous studies on this topic came from US Food and Drug-Administration-approved clinical trials restricted to on-label DES use. The current results, they say, “should be reassuring that DES are cost-effective compared with BMS in routine care.”

Dr. Applegate and colleagues point out, however, that acquisition costs vary among institutions, a factor that could affect generalizability of their results. In addition, current guidelines indicate even longer durations of dual antiplatelet therapy than were recommended at the time of the study.

Another potential issue, said William S. Weintraub, MD, of the Christiana Care Health System (Newark, DE), is that the study design assumes that the only difference between the 2 treatment eras was the choice of stent. This is not likely to be the case, he told TCTMD in a telephone interview, noting, “[I]f you look at very contemporary data, things have really changed a lot. . . . The devices we have today are so much better than we had with first-generation devices. And we’re just generally better at PCI. So that sets the limits for what we can learn from this study.”

In an e-mail communication, Dr. Applegate reported that newer DES are at least as effective as their predecessors and could potentially reduce very late stent thrombosis, limiting the need for prolonged dual antiplatelet therapy. Both factors might improve the cost-effectiveness of DES, he noted.

The price of clopidogrel used in the study is still fairly accurate, commented Dr. Kirtane, though this could change if Plavix (Bristol-Myers Squibb/Sanofi Pharmaceuticals Partnership, Bridgewater, NJ) goes generic. “It does appear that some of the restenosis and TVR rates might be lower in real world use with second-generation DES,” he said. But the biggest change is that stent prices are lower, and will probably continue to fall, now that several newer DES have entered the market, he added.

Dr. Kirtane also cautioned that the findings are expressed as the mean cost per TVR avoided, so patient selection is key. For example, he said, a focal large vessel lesion in an MI patient, depending on its location, might have a very low rate of restenosis.

Cost: How Big an Issue for Doctors?

“From a societal perspective, a treatment strategy (ie, DES) that improves patient outcomes by reducing morbid events (ie, TVR) at a cost [of] less than $10,000 per event avoided has been in general viewed favorably,” the paper notes. “For an individual hospital, the higher upfront costs of DES, however, may not be fully covered by reimbursement rates, especially if multiple stents are required during the procedure. Use of this kind of data may be most beneficial in identifying specific patient and lesion subsets with either favorable, or unfavorable, incremental cost-effectiveness ratios.”

Asked about the clinician’s perspective, Dr. Applegate noted that cardiologists “are not accustomed to thinking about cost-effectiveness, only effectiveness. When a new therapy comes out, it is usually more effective and more expensive. . . . Physicians are still trained to choose more effective therapies, but we are being challenged by hospitals and third-party payers to support the cost effectiveness of these therapies. Ultimately, the hospital will intervene if it believes it is losing money with new therapies in spite of their effectiveness. It is our responsibility to understand these issues and defend our choice of more effective therapies.”

Dr. Weintraub said that while most clinicians are unsure about specific details related to cost-effectiveness when making treatment decisions, they tend to believe “that the avoidance of additional procedures down the line is paying for drug-eluting stents, which is probably the case.”

For his part, Dr. Kirtane said that these issues are most relevant to hospitals setting policy. “When clinicians make decisions, usually you’d hope that they would be blinded to some of that,” he commented.

Study Details

Index procedure costs were estimated using the actual costs for each stent in 2005 (BMS $975, sirolimus-eluting stents $2,100, and paclitaxel-eluting stents $2,550) multiplied by the number of stents placed per procedure. The calculation did not include other hospitalization costs related to the index procedure.

Patient records were used to estimate total duration of clopidogrel use in 91% of subjects. For the remainder, researchers assumed clopidogrel use lasted the recommended duration at the time of the study (1 month for BMS, 3 months for sirolimus-eluting stents, and 6 months for paclitaxel-eluting stents) or until death. Clopidogrel cost was based on the wholesale price in 2005 ($4.67 per day)

Source:

Schafer PE, Sacrinty MT, Cohen DJ, et al. Cost-effectiveness of drug-eluting stents versus bare metal stents in clinical practice. Circ Cardiovasc Qual Outcomes. 2011;Epub ahead of print.

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