Is Watchman Cost-effective? That Depends Where You Look

ORLANDO, FL—The Watchman device for closure of the left atrial appendage (LAA) is highly cost-effective compared with warfarin and dabigatran when estimates are based on data from the PROTECT AF trial, but the device is dominated by both medications when using PREVAIL data, a new study shows.

Because of the greater statistical certainty that comes from the larger size and longer follow-up of PROTECT AF, however, “the cost-effectiveness estimates from that may be more generalizable,” James Freeman, MD, MPH, of Yale University (New Haven, CT), told TCTMD.

He added before his poster presentation at the American Heart Association 2015 Scientific Sessions that the discrepant findings provided by the PROTECT AF and PREVAIL trials likely represent the possible range of cost-effectiveness for LAA closure with the Watchman (Boston Scientific), and said longer-term follow-up from the trials and a planned postmarketing LAA closure registry will provide important information about the therapy.

“It will be vital over the coming years as this gets rolled out in the United States to follow that closely,” he said.  

Freeman and colleagues used a Markov decision model to examine the cost-effectiveness of the Watchman device compared directly with warfarin using the clinical trial data and indirectly with dabigatran (Pradaxa; Boehringer Ingelheim) using RE-LY data in a hypothetical cohort of 65-year-old patients with A-fib, a moderate-to-high risk of stroke, and no contraindications to anticoagulation. The analysis used long-term data from PROTECT AF (mean 3.8 years) and 18-month data from PREVAIL to estimate cost-effectiveness over a lifetime.

Using assumptions based on PROTECT AF, LAA closure with the Watchman resulted in incremental cost-effectiveness ratios (ICERs) of $24,400 vs dabigatran and $20,140 vs warfarin, both well below thresholds typically used to define cost-effectiveness, Freeman said.

Using inputs from PREVAIL, however, the Watchman was dominated by both dabigatran and warfarin because of higher costs and lower efficacy.

Sensitivity analyses showed that estimates of cost-effectiveness were most sensitive to changes in the rates of stroke and intracranial hemorrhage and were not influenced much by rates of periprocedural adverse events—such as ischemic stroke, pericardial effusion, device embolization, and esophageal tear—or operator experience.

Using a willingness-to-pay threshold of $100,000 per quality-adjusted life-year, LAA closure with the Watchman was likely to be the most cost-effective option in 67% of cases based on PROTECT AF and in only 40% of cases based on PREVAIL.

Freeman noted that the findings are applicable only to patients who are eligible for oral anticoagulation because patients with contraindications were excluded from the randomized trials.

In explaining why the results differed so much based on which trial formed the basis of the analysis, Freeman pointed out that 4-year data are available from PROTECT AF and only 18-month data are available from PREVAIL and that intracranial hemorrhage in the periprocedural setting with the Watchman was more frequent in PREVAIL. When extrapolating event rates over the long term, using information from the trial with longer follow-up will provide more reliable estimates, he said.

To that point, he noted, a prior study using 18-month PROTECT AF data showed that the Watchman was cost-effective vs both warfarin and dabigatran but with slightly worse cost-effectiveness compared with the current results. Freeman said it would be interesting to see whether longer-term PREVAIL data will show a similar trend toward improving cost-effectiveness for the device.

Commenting on the study, Frederick Masoudi, MD, MSPH, of the University of Colorado Denver, told TCTMD that “these kinds of assessments are really important. It’s not enough to know that one treatment is better than another, particularly with technology.”

But, he added, what the study underscores is that the findings of cost-effectiveness analyses are very sensitive to the inputs that go into the models. In this case, stroke and intracranial hemorrhage rates drove the results.

“As important as it is to understand cost-effectiveness of therapies, we have to recognize that the approaches involve assumptions and those assumptions can vary even if they’re based on clinical trials and come out with disparate results,” he said.

It is difficult to conclude based on these findings whether the Watchman device is a cost-effective therapy for preventing stroke in patients with A-fib, which emphasizes the importance of making individualized decisions for patients while being honest about what is known or not known about the relative risks and benefits of different approaches, Masoudi said.

Better evaluation of the device in real-world settings, he noted, will be important and will come in postmarketing studies mandated by the FDA and set up through the National Cardiovascular Data Registry (NCDR).

Disclosures:

• Freeman reports no relevant conflicts of interest.
• Masoudi reports serving as the senior medical officer of the NCDR.

Related Stories:

•  After Years of Scrutiny, Watchman Ready for Prime Time
•  Meta-analysis Shows Watchman Still Noninferior to Warfarin, With Good Safety Outcomes
•  LAA Occlusion More Cost-effective Than Both Warfarin and Dabigatran for A-fib Patients