REVASCAT: Thrombectomy’s Impact in Acute Stroke Extends to 1 Year
LOS ANGELES—Functional status and quality of life remain higher beyond 90 days in patients with acute ischemic stroke who undergo mechanical thrombectomy than in medically treated patients, according to results of REVASCAT, the only one of the recent successful trials to follow patients out to 1 year.
Extended follow-up for the trial was presented here at the International Stroke Conference.
Outcomes remained nearly identical between the 90-day and 1-year follow-up, with that additional information allowing for more accurate assessments of the clinical effect and cost-effectiveness of the procedure, commented Wade Smith, MD, PhD, of the University of California, San Francisco, who was not involved in the study.
He pointed out to TCTMD that the standard 90-day follow-up used in stroke trials—as opposed to the 30 days used in other types of research—“was kind of just made up” for the early neuroprotective studies evaluating nimodipine because of the recognition that patients with stroke need more time to recover.
“The concern, though, is that if you’re dealing with a group of patients with very high comorbid diseases, these impacts aren’t going to be held for long,” Smith said.
REVASCAT shows that the benefits are sustained to at least 1 year, which is important for supporting cost-effectiveness analyses that often rely on assumptions of longer-term benefit,” Smith said. One such economic analysis was reported at the same session—showing that thrombectomy with the Solitaire FR device (Medtronic) was cost saving over a lifetime horizon—and it was based on the assumption that 90-day outcomes would be sustained over longer periods of time
“If you don’t have 1-year, 2-year, or 5-year data, you’re making a guess and [REVASCAT] was one of the few to ever follow a cohort of stroke patients that far out,” Smith said. “I think that’s actually very important for modeling the cost-utility of this treatment.”
Antoni Dávalos, MD, of Universitat Autònoma de Barcelona (Barcelona, Spain), presented the final 12-month results, which were a prespecified secondary objective of the trial. REVASCAT randomized 206 patients with strokes caused by proximal anterior circulation occlusions to medical therapy alone—which could include IV tPA if the patients were eligible—or to medical therapy plus thrombectomy with the Solitaire FR device. All patients could be treated within 8 hours and had small-to-moderate ischemic cores on neuroimaging.
The results at 1 year were consistent with the primary results reported at 90 days.
In terms of safety, there was no difference in the rate of mortality, which was 23.3% in the thrombectomy group and 24.3% in the control group (adjusted HR 1.04; 95% CI 0.59-1.83).
The primary efficacy endpoint was the distribution of modified Rankin Scale (mRS) scores expressed as a common odds ratio. At 1 year, that was 1.80 (95% CI 1.10-2.99), similar to the finding at 90 days (common OR 1.71; 95% CI 1.05-2.81).
The proportion of patients with an mRS score of 0 to 2, indicating functional independence, was higher in the thrombectomy group (43.7% vs 30.1%; adjusted OR 2.14; 95% CI 1.15-3.97), corresponding to a number needed to treat of 7. The finding was similar when looking at Barthel Index scores of 95 to 100.
Thrombectomy also resulted in greater improvements in health-related quality of life compared with medical therapy alone.
A benefit from intervention was seen across subgroups defined by age, baseline NIH Stroke Scale score, site of occlusion, time to treatment, receipt of IV tPA, and ASPECTS score.
Cost Dominance Found
After the REVASCAT presentation, Theresa Shireman, PhD, of Saint Luke’s Mid America Heart Institute (Kansas City, MO), presented an economic substudy of the SWIFT PRIME trial, which showed that IV tPA plus thrombectomy with the Solitaire FR or Solitaire 2 devices improved functional outcomes at 90 days in patients with large vessel occlusions compared with IV tPA alone.
Although prior cost-effectiveness analyses have been performed, they have relied on assumptions about the costs of therapy—rather than empirical data—and older historical data for their models, Shireman said. The current study, on the other hand, was prospectively designed and used actual cost data (up to 90 days) from the trial. Resource use and life expectancy beyond 90 days was estimated based on an external cohort of acute ischemic stroke patients who had 90-day mRS scores available and were followed for about 4 years, as well as data from Medicare claims and the National Death Index.
The analysis showed that index hospitalization costs were $17,183 higher in the Solitaire group, driven by the procedure cost of $14,669. From discharge to 90 days, there was a greater need for inpatient rehabilitation or skilled nursing care and for outpatient rehabilitation in the IV tPA group, resulting in lower costs that were lower by $4,904 in the Solitaire group. Combining the index hospitalization and follow-up to 90 days, costs were $12,279 higher in the Solitaire group.
Quality of life improved in both arms of the trial through 90 days, but the gains were greater after thrombectomy. Also, projected survival was longer in the Solitaire group (11.76 vs 10.02 years).
Over a lifetime horizon, it was estimated that costs in the Solitaire group would be lower ($215,781 vs $238,984) and that quality-adjusted life-years (QALYs) would be higher (6.789 vs 5.046), which means that thrombectomy would be economically dominant, or cost saving.
Thrombectomy remained dominant in nearly all subgroups studied. The exception was in patients older than 75 years, although the treatment was still considered cost-effective.
Shireman calculated that it would take less than 2 years (about 21.5 months) for the costs in patients receiving IV tPA alone to exceed those in patients undergoing thrombectomy.
“For Medicare recipients, their life expectancy is far beyond 2 years typically if a person has a stroke so I think that’s great that it pays off that quickly,” commented Smith, who was on the data and safety monitoring board for SWIFT PRIME. He said cost-utility analyses like this one are important when justifying to governments that treatments should be covered.
“The fact that you can say that treatment not only improves patients but that society will pay for that really helps us at the political level to say that we need to provide it for everybody because it makes sense,” he said.
Dávalos A, Cobo E, Molina C, et al. Randomized trial of revascularization with Solitaire FR device versus best medical therapy in the treatment of acute stroke due to anterior circulation large vessel occlusion presenting within eight hours of symptom onset: REVASCAT trial, final results at 12 months. Presented at: International Stroke Conference; February 18, 2016; Los Angeles, CA.
Shireman TI. Cost-effectiveness of Solitaire + IV t-PA for acute ischemic stroke: results from the SWIFT PRIME trial. Presented at: International Stroke Conference; February 18, 2016; Los Angeles, CA.
- REVASCAT was funded by an unrestricted grant by Covidien and sponsored by Fundació Ictus.
- The SWIFT PRIME trial, including the economic substudy was funded by Medtronic.
- Dávalos reports serving on the steering committee for the STAR trial by Covidien.
- Shireman reports receiving funding from the National Multiple Sclerosis Society and the NIH, and being involved in projects for the Patient-Centered Outcomes Research Institute.
- Smith reports receiving compensation for serving on an independent data and safety monitoring board for an ongoing trial by Stryker.