Incidence of mechanical thrombectomy among stroke patients brought directly to a comprehensive stroke center versus transfer from a primary stroke center in upstate New York

Abstract

BackgroundFaster time to treatment for stroke is associated with improved outcomes. In cases of large vessel occlusion (LVO), standard of care treatment with thrombectomy can only be provided at a comprehensive stroke center (CSC). We examine the outcomes of patients who are directly brought to our center, a CSC, compared to those seen at a primary stroke center (PSC) and then transferred.MethodsPatients with LVO presenting to our center from 1/1/2019 to 12/31/2019 were included. Cohorts of patients presenting first to a PSC and presenting first to a CSC were compared. Demographics and outcome metrics (Discharge Modified Rankin Scale (mRS) and National Institute of Health Stroke Severity Scale (NIHSS) scores) were obtained for all LVO patients. Imaging was also assessed.ResultsOf 864 stroke admissions, 346 had LVO (40%) with 183 (53%) transferring from a PSC and 163 (47%) presenting directly. Similar percentages of each cohort were taken for thrombectomy (25.1% transfer and 31.3% direct). However, as distance between PSC and CSC increased, likelihood of thrombectomy decreased. Transfer patients were more likely to be excluded from thrombectomy secondary to a large volume of complete stroke (p = 0.0001). Direct presenters had lower discharge mRS scores than transfer patients (p < 0.01), however, severity of stroke upon admission was similar in the two groups.ConclusionPatients transferred from a PSC were more likely to have a worse outcome at time of discharge than those presenting directly to our center. Large volume of completed stroke was a frequent reason for exclusion from thrombectomy. Optimizing stroke protocols to CSC in cases of LVOs may result in better outcomes.

Keywords: Stroke; patient outcome assessment; thrombectomy.

Figure 1.

Flow chart of inclusion.

Figure 2.

mRS shift analysis. The table above shows a proportion analysis of mRS scores between the Direct group and the Transfer group. An mRS score of 0−1 indicates excellent outcomes and a score between 0−2 indicates functional independence. Patients brought directly to our center were significantly more likely to be discharged with minimal disability and excellent outcomes and functional independence (p = 0.1 and p = 0.05, respectively). On the other hand, the rate of mortality was the same in both groups. The figure below represents a shift analysis of scores in the two groups. More patients in the Direct group had scores in the 0−3 range, whereas transfer patients were more likely to fall in the 4−6 range.

Figure 3.

mRS shift analysis in sub-group of patients that received MT. The table above shows a proportion analysis of mRS scores between the Direct group and the Transfer group that received MT. An mRS score of 0−1 indicates excellent outcomes and a score between 0−2 indicates functional independence. Patients in the Transfer group and Direct group had similar mRS outcomes after being taken for MT. The figure below represents a shift analysis of scores in the two groups. Though not significant, more patients in the Direct group had scores in the 0−3 range.

Figure 4.

Contraindications for thrombectomy. The figure above lists reasons why patients did not undergo thrombectomy on the y-axis. The number of patients that fell into each group are plotted on the x-axis for both the Transfer and Direct groups. The Direct group was significantly less likely to have had a completed stroke as compared to the Transfer group (p = 0.0001). Additionally, the Direct group was more likely to have symptom improvement so that mechanical thrombectomy was not indicated (p = 0.05).