Using MRI to look for intraplaque hemorrhage could be a cost-effective way to inform treatment decisions in those with asymptomatic carotid artery stenosis (CAS), according to a decision-making analytic model described in a study published online in Radiology.
Rather than a stroke prevention strategy of intensive medical therapy for all asymptomatic CAS patients, an imaging-based strategy that sends a subset of these patients for immediate carotid endarterectomy when intraplaque hemorrhage is detected on MR imaging of carotid artery plaque results in an incremental cost-effectiveness ratio of $16,000 per quality-adjusted life year, according to the model.
“Our results suggest that imaging-based risk stratification may be of greatest value in relatively younger patients (because of their greater life expectancies and opportunity to benefit from imaging),” wrote Ajay Gupta, MD, of Weill Cornell Medical College in New York City, and colleagues. “In such patients, it is likely that the initial perioperative [carotid endarterectomy] complication risks are eventually outweighed by the long-term reduction in stroke risk over a longer life expectancy as compared with older patients.”
The researchers noted that recent evidence has shown intraplaque hemorrhage is a marker of atherosclerotic plaque that is more likely to spark an ipsilateral stroke or transient ischemic attack. However, while MRI’s ability to discriminate tissues found in atherosclerotic plaque may be valuable for providing stroke risk information, it was unclear whether it would be cost-effective in the decision-making process.
Gupta and colleagues’ model compared medical therapy-based management with the MRI-based strategy using a rule that patients in the medical therapy-only group could only undergo carotid endarterectomy with substantial carotid artery stenosis disease progression. Those with intraplaque hemorrhage would immediately undergo carotid endarterectomy in addition to ongoing intensive medical therapy.
Results showed the MRI-based strategy had a longer life expectancy at 12.95 years, compared with 12.65 years for the medical therapy-based strategy. MRI also led to more lifetime quality-adjusted life years (10.05 vs 9.96).
Lifetime costs were $15,297 for the MRI-based strategy compared with $13,699 for the medical therapy-based strategy. For a base-case 70-year-old patient, the incremental cost-effectiveness ratio for MRI compared with the medical therapy strategy was $16,000 per quality-adjusted life year. Incremental cost-effectiveness ratios for the MRI-based strategy were $3,100 and $73,000 per quality-adjusted life year when using starting patient ages of 60 and 80 years, respectively.
The willingness-to-pay threshold is $100,000 per quality-adjusted life year, noted Gupta and colleagues.
They added that their results are particularly interesting given that the U.S. Preventive Services Task Force has recommended against population-based screening for asymptomatic CAS. If these results are verified, screening using MRI testing of intraplaque hemorrhage may in fact offer potential benefits. The authors feel that intraplaque hemorrhage may be the most clinically valuable MRI plaque risk marker since it can be determined quickly without specialized equipment or gadolinium-based contrast agents.
“[T]he decision to undergo intensive medical therapy alone versus [carotid endarterectomy] plus intensive medical therapy poses a controversial and challenging clinical dilemma in patients with asymptomatic CAS,” wrote Gupta and colleagues. “MR imaging [intraplaque hemorrhage] testing can help to identify patients with CAS who are at higher risk for stroke.”