Model finds Watchman device is more cost-effective than warfarin and oral anticoagulants

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A model found that treatment with the Watchman device was more cost-effective than warfarin to reduce the lifetime stroke risk of patients with nonvalvular atrial fibrillation.

The Watchman device (Boston Scientific) became more cost-effective than warfarin at year 7 and has an incremental cost-effectiveness ratio (ICER) of $42,994 per quality-adjusted life-year (QALY). Meanwhile, novel oral anticoagulants proved more cost-effective than warfarin at 16 years with an ICER of $48,446 per QALY.

Lead researcher Vivek Y. Reddy, MD, of Mount Sinai Medical Center in New York, and colleagues published their results online in the  Journal of the American College of Cardiology on Dec. 14.

They mentioned that nearly six million people in the U.S. have atrial fibrillation and that Medicare spends an estimated $16 billion on the disease each year. Although warfarin is cheap and has been the standard of care for decades, they noted it is associated with an increased risk of bleeding, lower quality of life and low adherence rates.

In recent years, the FDA has approved four oral anticoagulants (dabigatran, rivaroxaban, apixaban, and edoxaban), which have been found to be noninferior to warfarin for ischemic stroke reduction and superior for hemorrhagic stroke and all-cause mortality. However, patients taking those drugs are at an increased risk for gastrointestinal bleeding, according to the researchers.

In March, the FDA approved the Watchman device, which is intended for percutaneous closure of the left atrial appendage and to reduce the risk of stroke in patients with non-valvular atrial fibrillation. The device is intended as an alternative to warfarin or novel anticoagulants.

The researchers used Microsoft Excel and developed a Markov model from the perspective of the Centers for Medicare & Medicaid Services with a lifetime horizon defined as 20 years and a cycle length of 3 months. Within the model, they assigned patients to one of three treatment groups: Watchman device, novel oral anticoagulants or adjusted-dose warfarin. They assumed that all patients were healthy entering the model and transitioned into new health states when they died or had a clinical event.

They evaluated cost-effectiveness using the U.S. accepted willingness-to-pay threshold of $50,000 per QALY gained.

After one year, patients in the Watchman group had higher costs and fewer QALYs compared with the warfarin group. The Watchman group gained more QALYs by year three and became cost-effective by year 7. By year 10, the Watchman became more effective and less costly, and it remained that way for the remainder of the 20-year time period.

Meanwhile, patients receiving novel anticoagulants saw efficacy benefits at year 1 and cost-effectiveness benefits at year 16. However, novel anticoagulants did not save money relative to warfarin during the 20 years, although the ICER decreased each year.

The Watchman device was less expensive and more effective than novel anticoagulants by year 5, and the benefits continued throughout the 20 years. During a patient’s lifetime, the Watchman device provided an estimated additional 0.298 life-years and 0.349 QALYs compared with novel anticoagulants.

The researchers mentioned that patients implanted with the Watchman device do not have adherence issues and receive lifelong stroke prophylaxis without the risk of complications associated with oral anticoagulants. They added that the risks associated with the device are also reduced with operator experience.

The model had a few limitations, according to the authors, including that it only allowed for one clinical event every three months. They noted that data were taken from multiple sources, individual trials had different time horizons and all data were extrapolated to 20 years.

“Longer-term clinical studies are needed to define more clearly the return on investment in nonpharmacologic strategies to prevent stroke in patients with [atrial fibrillation] and incorporate the findings into clinical practice guidelines and reimbursement policies,” they wrote.