Key Points:
- Researchers attempt to calculate how many strokes due to large-vessel occlusion could be treated endovascularly
- Less than half of eligible cases now treated in the United States
Less than half of the patients with strokes due to large-vessel occlusion (LVO) who are eligible for endovascular therapy actually undergo it, according to a new study that estimates the nationwide potential for growth based on a single-center experience. But even with much room to grow, efforts must be made to improve systems of care, researchers said in their paper published online July 18, 2016, in the Journal of NeuroInterventional Surgery.
Ansaar T. Rai, MD, of West Virginia University (Morgantown, West Virginia), and colleagues conducted a population-based study of patients with acute ischemic stroke discharged from their tertiary-level hospital during a 3-year period. They calculated the incidence of LVO and then extrapolated it to the US population. Patients with anterior circulation LVOs were considered eligible for thrombectomy if they were within 6 hours of symptom onset and had an Alberta Stroke Program Early CT Score (ASPECTS) of 6 or greater.
“At my institution, we do 10 thrombectomies per 100,000 person-years per year,” Dr. Rai told Neurovascular Exchange in a telephone interview. “If we have an LVO incidence of 24 per 100,000 person-years and we are doing 10 thrombectomies,” he said, “that means we are only treating about 50% of patients with LVO.”
Less Than Half of Eligible Cases Get Treated
During the 3-year study period, 1,157 patients with acute ischemic stroke were discharged from the institution and LVO occurred in 11.1%. More half (58.1%) of patients with LVO presented within 6 hours of symptom onset. In all, 109 patients had an anterior circulation LVO, with 73.4% of this group having an ASPECTS of 6 or greater.
Dr. Rai and colleagues’ hospital handles about an 85% share of patients with stroke from the local area. Based on its primary service area population of 210,000, and accounting for the remaining 15% of stroke patients, the researchers estimated an incidence of 24 LVOs per 100,000 person-years.
About 20 per 100,000 people per year had anterior LVO, of which about 10 per 100,000 per year were eligible for thrombectomy. Considering a longer time horizon as well as patients with basilar artery occlusion and potentially treatable M2 occlusions brings the total number of thrombectomy-eligible patients from 10 to 20 per 100,000 people per year, the investigators say. “An estimated range of 10,000-20,000 annual thrombectomy procedures yield 3-6 mechanical thrombectomies per 100,000 person-years, indicating a significant potential for growth.”
Based on the 2015 population, their estimates would yield about 696,000 total cases of acute ischemic stroke for the entire US population, of which about 78,000 are LVOs.
While optimistic about the potential for growth, the researchers conclude: “The history of coronary interventions illustrates that it will be impossible to treat every eligible patient despite all possible efforts; however, developing systems of care can steadily increase the proportion of eligible patients who are treated and these estimates can serve as markers for gauging progress.”
In addition, they acknowledge that the “true treatment eligibility could be lower than these estimates because patients with significant comorbidities, poor baseline functional status, or unfavorable vascular anatomy are not accounted for and can lower the target population.”
Wider Application
To Neurovascular Exchange, Philip M. Meyers, MD, of Columbia University (New York, NY), said the results of this study are very positive and show that there is a larger potential population of stroke patients than what is currently being treated. However, Dr. Meyers expressed uncertainty about how to best extrapolate these results from Morgantown, WV, to the whole country.
“In some large cities, there are impediments to rapid triage. For instance, some cities do not allow helicopter transport in the city proper, and it may be difficult to move patients around quickly by ground transport,” Dr. Meyers commented in a telephone interview. “The ability to treat more patients with large vessel occlusions will depend, in part, on the availability of endovascular stroke of services and whether hospitals are equipped to deal with stroke patients.”
Dr. Rai mentioned some of these issues as well. Local emergency medical services brings every stroke patient to his institution because it is the largest in the area and they know it is in the patient’s best interest, he said. “But you cannot mandate that type of thing in Chicago or New York City where you have 7 or 8 hospitals within blocks of each other all competing for patients.”
“What is happening today is that stroke is being treated in a way that is now validated, approved by [the Centers for Medicare & Medicaid Services] and is a service line that generates revenues for hospitals,” Dr. Rai said. “Some patients with stroke will end up at smaller hospitals that have invested resources into treating stroke, even though high volume centers have been shown to provide better treatment for niche treatments.”
In urban areas, this could potentially be helped through local legislation that, for example, would designate a stroke hospital each week where every patient with stroke is transported too, Dr. Rai suggested. In addition, in order for patients to get the best treatment, it must be noted that not every hospital is equipped to handle large-vessel strokes because it is very resource intensive.
“If these smaller hospitals cannot handle these patients, they should see if there is a partner hospital where patients can be sent and if they have established a system of care that allows for the seamless transfer of patients to a hospital that is nearby,” Dr. Rai said.
Source:
Rai AT, Seldon AE, Boo S, et al. A population-based incidence of acute large vessel occlusions and thrombectomy eligible patients indicates significant potential for growth of endovascular stroke therapy in USA. J NeuroIntervent Surg. 2016;Epub ahead of print.
Disclosures:
- Dr. Rai has a consulting agreement with Stryker Neurovascular.
- Dr. Meyers reports no relevant conflicts of interest.
