Correlations Between Physician and Hospital Stroke Thrombectomy Volumes and Outcomes: A Nationwide Analysis

Does Adding Thrombectomy-Capable Stroke Centers in a Regional Stroke Care System Affect Procedural Volume?

BACKGROUND

To maintain procedural proficiency and certification according to the standards set by The Joint Commission-which accredits health care centers in the United States-thrombectomy-capable stroke centers (TSCs) must achieve a minimum annual procedural volume. The addition of thrombectomy-capable centers in a regional stroke care system has the potential to increase access but also to decrease patient presentations and procedural volume at nearby centers. This study sought to characterize the impact of certifying additional thrombectomy-capable centers on procedural volume by center in a large, urban Emergency Medical Services (EMS) system.

METHODS

Data were collected from each designated thrombectomy-capable center in Los Angeles (LA) County from January 1, 2018 through June 30, 2022, during which a net total of five thrombectomy-capable centers were newly designated in the County. Per center volume for ischemic stroke presentations, intravenous (IV) thrombolysis administrations (IV tissue plasminogen activator [tPA]), and thrombectomy were tabulated by six-month interval. Median last-known-well-to-procedure times by LA County Public Health service planning area (SPA) were calculated. The effect of the number of designated centers on procedural volumes per center and median last-known-well-to-procedure times were analyzed via a linear mixed effects model with a log link function.

RESULTS

Procedural volume, ischemic stroke presentation volume, and last-known-well-to-procedure times had high variability over the time period studied. Nonetheless, the median values for each metric in this EMS system remained largely stable over the study period. There was no statistically significant association between the number of thrombectomy-capable centers and per center procedural volumes or times-to-procedure.

CONCLUSION

The designation of additional thrombectomy-capable centers in a regional stroke care system was not significantly associated with the volume of procedures by center or times-to-procedure, suggesting that additional centers may increase patient access to time-sensitive interventions without diluting patient presentations at existing centers.

Inter-proceduralist variability in angiographic outcomes after stroke thrombectomy and the importance of quality over quantity of passes

BACKGROUND

Complete recanalization (CR, modified Treatment in Cerebral Ischemia (mTICI) score of 2c or better) is associated with favorable outcomes after endovascular thrombectomy (EVT) for stroke patients. However, the degree of inter-proceduralist differences in CR rates is unknown, and whether higher CR rates are being achieved by performing more passes or by focusing on first-pass effectiveness is also unclear.

METHODS

This was a multicenter retrospective study of anterior circulation large vessel occlusion stroke patients in the United States from 2016 to 2022. Patients treated by proceduralists with at least 50 cases were included. CR rates for each proceduralist were assessed and proceduralists were divided into tertiles. First-pass effect (FPE, defined as CR after one pass) and the number of passes for patients treated by the top tertile of proceduralists were compared with the bottom tertile. Mediation analyses were conducted to assess causal links between CR rates and number of passes or FPE.

RESULTS

A total of 1096 EVTs performed by 11 proceduralists were identified. CR rates were highly variable across providers (43.1% to 75.3%, p<0.001). Patients treated by the top tertile were more likely to experience FPE (OR 1.99, 95% CI 1.49 to 2.67, p<0.001) and did not undergo more passes (p=0.69) compared with the bottom tertile. Higher rates of FPE among patients was a significant mediator of higher odds of CR among patients treated by the top tertile (p<0.001).

CONCLUSIONS

Angiographic outcomes among EVT proceduralists are highly variable. Proceduralists who achieve higher rates of CR are doing so with higher rates of FPE, not more passes.

Impact of hospital readmission site on outcomes in acute ischemic stroke patients undergoing mechanical thrombectomy: a nationwide analysis

BACKGROUND

Mechanical thrombectomy (MT) significantly improves outcomes in patients with acute ischemic stroke due to large vessel occlusion. There is limited understanding of how the site of hospital readmission after MT influences patient outcomes. Addressing this gap may be important for optimizing post-MT care and improving long-term outcomes for stroke patients.

METHODS

We conducted a retrospective cohort analysis using data from the Nationwide Readmissions Database, focusing on acute ischemic stroke patients who underwent MT between 2016 and 2019. Multivariable Cox regression and Fine and Gray competing risks models were used to assess the impact of readmission site on patient outcomes, including mortality and the likelihood of discharge to home.

RESULTS

The analysis included 18 330 patients readmitted within 90 days post-MT, with 63.7% readmitted to index hospitals and 36.3% to non-index hospitals. Readmission to the index hospital was not significantly associated with mortality but was linked to a higher likelihood of discharge to home (subdistributed HR 1.22, 95% CI 1.13 to 1.32, P<0.001), a lower likelihood of longer hospital stay (OR 0.81, 95% CI 0.72 to 0.90, P<0.001), and lower hospital cost (β = -3345.25, 95% CI -5786.46 to -904.04, P=0.007).

CONCLUSION

This nationwide analysis suggests that for acute ischemic stroke patients treated with MT, readmission to index hospitals within 90 days is associated with a higher likelihood of home discharge, shorter length of stay, and lower hospital cost. Further research is warranted to better understand the underlying causes of these disparities and to enhance continuity of care for this vulnerable patient population.

Association of endovascular thrombectomy volume and outcomes in acute ischemic stroke: A National Inpatient Sample Study

BACKGROUND

Previous studies suggest a positive relationship between higher hospital endovascular thrombectomy (EVT) volume and improved outcomes. We investigated this association using the National Inpatient Sample (NIS) database from 2016 to 2020.

METHODS

A cross-sectional analysis of the NIS examined the relationship between hospital EVT volume and outcomes. Data on clinical and demographic variables were collected. Outcomes included favorable functional outcome (discharge home without assistance), inpatient mortality, and intracerebral hemorrhage (ICH). Hospitals in the top quintile of annual EVT volume were classified as high-volume centers. We conducted univariate, multivariate, nearest neighbor matched analysis, and an exploratory analysis to identify annual EVT volume cutoffs.

RESULTS

Among 114,640 patients with EVT, 24,415 (21.3%) were treated at high-volume centers. High-volume centers had higher rates of favorable functional outcomes in univariate (odds ratio (OR) 1.20, p < 0.001), multivariate (adjusted OR (aOR) 1.19, p = 0.003), and matched analysis (OR 1.14, p = 0.028). Before matching, inpatient mortality was lower in high-volume centers (OR 0.83, p < 0.001), but this difference was not significant in univariate and matched analyses. No differences in ICH were observed. Functional benefit was noted at ≥ 50 EVTs annually, with centers performing  ≥ 175 EVTs showing significantly higher benefits (aOR 1.42, p = 0.002).

CONCLUSIONS

Increased hospital EVT volume is associated with modestly improved functional outcomes in patients with acute ischemic stroke. Functional improvements are evident at ≥ 50 EVTs annually and increase with higher case volumes, without associated increases in inpatient mortality or ICH.

Trends in utilization and impact of hospital procedural volume on mortality after endovascular thrombectomy for acute ischemic stroke

OBJECTIVES

Endovascular thrombectomy (EVT) has become an established treatment for eligible acute ischemic stroke (AIS) patients, but data on mortality trends and the association between procedural volume and outcomes in the United States is limited.

MATERIALS AND METHODS

This retrospective study analyzed data from the Nationwide Readmissions Database (NRD) to investigate trends in EVT utilization, outcomes, and the relationship between hospital procedural volume and inpatient mortality for AIS admissions between 2016-2020. Patients undergoing EVT were identified using ICD-10 procedure codes. Hospitals were categorized into quintiles based on EVT volumes, and mortality rates compared across quintiles. Multivariable regression identified predictors of mortality.

RESULTS

Of 2,535,777 AIS admissions, 90,110 (3.6 %) underwent EVT (median age of 70 and 50 % female in both groups). EVT utilization increased from 2.8 % in 2016 to 3.9 % in 2020 (p < 0.001). Patients receiving EVT had higher prevalence of atrial fibrillation and coronary artery disease but lower rates of hyperlipidemia and tobacco use. Inpatient mortality was higher with EVT (13 % vs 4 %, p < 0.001) but declined from 16 % in 2016-2017 to 12 % in 2020 (p < 0.001). Hemiparalysis and atrial fibrillation were associated with higher EVT likelihood. Mortality decreased with higher hospital EVT volume. After adjustment, higher procedural centers were associated with lower mortality.

CONCLUSION

EVT utilization for AIS increased nationally from 2016-2020 while associated mortality declined. Higher hospital procedural volumes were associated with lower mortality.

Characteristics of Mortality After Endovascular Thrombectomy in Patients with Acute Ischemic Stroke

Purpose

Despite significant advancements in the treatment of acute ischemic stroke (AIS) with endovascular thrombectomy (EVT), post-EVT mortality remains a considerable concern. However, there is a lack of real-world epidemiological data delineating the characteristics of mortality for EVT, particularly in recent years following the widespread promotion of EVT treatment for stroke patients.

Methods

This multicenter, retrospective study collected data from 721 AIS patients who died following EVT across 33 hospitals in Sichuan Province, China, from January 2019 to September 2022. The analysis sought to identify the primary causes of death within 30 days post-EVT and explore their related clinical features.

Results

The leading causes of death were malignant cerebral edema (MCE) in 365 patients (50.6%), pneumonia in 180 patients (25%), and symptomatic intracranial hemorrhage (sICH) in 94 patients (13%). MCE was the predominant cause of death in anterior circulation strokes, while pneumonia prevailed in posterior circulation strokes. MCE was also the primary cause of death within one week post-EVT, but pneumonia became increasingly dominant over time. Large vessel occlusion and lower reperfusion success rate were significantly correlated with MCE. Advanced age increases the risk of death from pneumonia. Tandem occlusion and procedural complications tend to correlate with mortality from sICH.

Conclusion

This study revealed that the principal causes of death after EVT included MCE, sICH, and pneumonia. MCE was found to be correlated with unsuccessful reperfusion. sICH was associated with procedural complications and the operators' experience. Pneumonia was linked to post-EVT management, particularly for those who survived for one week.

Geographic Access to High-Volume Mechanical Thrombectomy Centers in Florida, 2019

Background and Objectives

Mechanical thrombectomy (MT) improves outcomes for acute ischemic stroke (AIS) due to large vessel occlusion, but is time sensitive and requires specialized infrastructure. Professional organizations and certification bodies have promulgated minimum procedural volume standards for centers and for individual proceduralists but it is unclear whether enforcing these requirements would decrease geographic access to MT. Therefore, we sought to evaluate the potential impact of applying a minimum procedural volume threshold on geographic access to MT.

Methods

We identified all hospital discharges for stroke where an MT procedure was performed at any nonfederal hospital in Florida in 2019 using statewide hospital discharge data. We then generated geographic service area maps based on prespecified ground transport distances for the subset of hospitals that performed at least 1 MT and for those that performed at least 15 MTs that year, the minimum volume threshold required for thrombectomy capable and comprehensive stroke centers by the Joint Commission. Then, using zip code centroids and patient-level discharge hospital data, we computed the proportion of patients with AIS who lived within each of the generated service areas.

Results

A total of 105 of 297 hospitals performed MT; of those, 51 (17%) were low-volume centers (1-14 MTs/year) and 54 (18%) were high-volume centers (≥15 MTs/year). High-volume centers accounted for nearly 95% of all MTs performed in the state. Most patients hospitalized with AIS (87%) lived within 20 miles (or an estimated as a 1-hour driving time) of a hospital that performed at least 1 MT, and all (100%) lived within 115 miles (or estimated as 3-hour driving time). Setting a minimum MT volume threshold of 15 would decrease the proportion of stroke patients living within 1-hour driving time of an MT center from 87% to 77%.

Discussion

In 2019, most Florida stroke patients lived within a 1-hour ground transport time to a center that performed at least 1 MT and all lived within 3-hour driving time of an MT center, irrespective of whether a minimum procedural volume threshold of 15 cases per year was applied or not.

High mechanical thrombectomy procedural volume is not a reliable predictor of improved thrombectomy outcomes in patients with acute ischemic stroke in the United States

BACKGROUND

The volume of mechanical thrombectomy (MT) performed at hospitals is used as one of the criteria for advanced-level designation for stroke care.

OBJECTIVE

Our study sought to determine the relationship between annual MT procedural volume and in-hospital outcomes in acute ischemic stroke patients undergoing MT in the United States.

METHODS

We analyzed the National Inpatient Sample from 2016 to 2020. The hospitals were grouped into quartiles based on the volume of MT procedures performed within the calendar year. We compared the rates of routine discharge/home health care; in-hospital mortality, and post-treatment intracranial hemorrhage (ICH) between the quartiles after adjusting for potential confounders.

RESULTS

Patients undergoing MT ranged from 15,395 in quartile 1 to 78,510 MT in quartile 4. There were lower rates of discharge home/self-care of 22.5%, 20.8%, and 20.8% for quartiles 2, 3, and 4, respectively, compared with 34.9% in quartile 1. The odds of ICH increased to 1.81 (p < 0.001), 1.84 (p < 0.001), and 1.98 (p < 0.001) among the quartiles from lowest to highest procedural volumes. The odds of home discharge/self-care decreased to 0.66 (p < 0.001), 0.60 (p < 0.001), and 0.63 (p < 0.001) among the quartiles from lowest to highest procedural volumes. The odds of in-hospital mortality increased to 1.92 (p < 0.001), 1.99 (p < 0.001), and 1.84 (p < 0.001) among the quartiles from lowest to highest procedural volumes.

CONCLUSIONS

We observed a paradoxical relationship between adverse outcomes and the annual procedural volume of MT at the hospital presumably due to the higher severity of acute ischemic stroke treated at high-volume hospitals.

Transportation for Patients with Stroke in Need of Mechanical Thrombectomy: A Simulation-Based Study in Hyogo Prefecture, Japan

Objective

This study aimed to simulate patient transportation to a mechanical thrombectomy (MT)-capable hospital within 60 minutes, taking into account patient volume (demand side of healthcare) and hospital capacity to accept patients (supply side of healthcare).

Methods

Simulations were conducted in Hyogo Prefecture, Japan. The estimates of the annual number of patients with stroke eligible for MT in 2020 were based on the incidence of stroke by age group and the percentage of patients with stroke indicated for MT in existing publications. Patients were then randomly placed on a 1 km2 mesh map. The patients were randomly generated 100 times using R software (version 4.1.2; R Foundation for Statistical Computing, Vienna, Austria). Hospitals were selected based on 2 criteria: (1) actual provision patterns (39 hospitals) and (2) consolidated patterns (12 hospitals). Simulations were performed using ArcGIS Pro (version 10.8; Esri, Redlands, CA, USA) and Network Analyst extension (Esri) in 3 cases: (1) number of patients estimated from the population in 2020 transported to hospitals that provided MT, (2) number of patients estimated based on the 2020 population transported to selected hospitals in the case of consolidation, and (3) number of patients estimated based on 2040's projected population and transportation to the selected hospitals.

Results

In Case 1, the estimated annual number of patients undergoing MT in 2020 was 976. The average number of patients undergoing MT and transported was 961, indicating that 98% (961/976) of the total generated patients could be transported within 60 min. In Case 2, the average number of patients undergoing MT and transported was 940, indicating that 96.3% (940/976) of the total patients could be transported within 60 min. In Case 3, the average number of patients undergoing MT and transported was 1184, showing that 95.1% (1184/1244) of the total generated patients could be transported within 60 min. A few patients in rural areas and remote islands required longer transport times.

Conclusion

The simulations showed that patient estimates from the incidence of cerebral infarction by age group and the percentage of patients with stroke indicated for MT were similar to the actual values. The simulation was closed to reality when both the supply and demand sides of healthcare were considered. Thus, this simulation study informs future healthcare policy by demonstrating the geographic distribution of human and capital resources and potential cost reduction through consolidation, taking into account demographic changes.

Higher proceduralist stroke thrombectomy volume is associated with reduced inpatient mortality

BACKGROUND

The aim of this study was to determine the impact of endovascular thrombectomy (EVT) proceduralist volume on in-hospital mortality in acute ischemic stroke (AIS) patients.

METHODS

We performed a retrospective cohort study using the 2020 Florida State Inpatient Database, including adult patients who had a diagnosis of AIS and underwent EVT during the same admission. The primary study outcome was in-hospital death. We used Youden's Index to define an optimal threshold for number of EVTs/year/provider. Based on this cut-point, the cohort was dichotomized into low and high proceduralist volume groups. We fit logistic regression models to mortality in the full cohort, both as univariate analyses and after adjusting for covariates.

RESULTS

Among 3143 AIS patients who underwent EVT, 1907 patients across 59 hospitals and 106 providers met our inclusion criteria. Among the providers, the median number of EVTs performed was 13.5 (IQR 7-25). The optimal cut-point was 17 EVTs. Demographics and comorbidities were similar between the cohorts. The high volume strata had a lower rate of in-hospital mortality (low volume 11.0% vs high volume 7.2%, P=0.005). After adjusting for potential confounders, high proceduralist volume remained significantly associated with lower odds of in-hospital death (OR 0.52, 95% CI 0.36 to 0.76, P=0.001). The difference in absolute risk of death was 4.8% (P=0.005).

CONCLUSIONS

We found that high proceduralist volume, defined by ≥18 EVTs/year, was associated with reduced in-hospital morality. Further research is necessary to understand the effects of proceduralist experience and benchmarks for technical proficiency in stroke care.

Physician Transfer Versus Patient Transfer for Mechanical Thrombectomy in Patients With Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

Physician transfer is an alternate option to patient transfer for expedient performance of mechanical thrombectomy in patients with acute ischemic stroke.

METHODS AND RESULTS

We conducted a systematic review to identify studies that evaluate the effect of physician transfer in patients with acute ischemic stroke who undergo mechanical thrombectomy. A search of PubMed, Scopus, and Web of Science was undertaken, and data were extracted. A statistical pooling with random-effects meta-analysis was performed to examine the odds of reduced time interval between stroke onset and recanalization, functional independence, death, and angiographic recanalization. A total of 12 studies (11 nonrandomized observational studies and 1 nonrandomized controlled trial) were included, with a total of 1894 patients. Physician transfer was associated with a significantly shorter time interval between stroke onset and recanalization with a pooled mean difference estimate of -62.08 (95% CI, -112.56 to -11.61]; P=0.016; 8 studies involving 1419 patients) with high between-study heterogeneity in the estimates (I2=90.6%). The odds for functional independence at 90 days were significantly higher (odds ratio, 1.29 [95% CI, 1.00-1.66]; P=0.046; 7 studies with 1222 patients) with physician transfer with low between-study heterogeneity (I2=0%). Physician transfer was not associated with higher odds of near-complete or complete angiographic recanalization (odds ratio, 1.18 [95% CI, 0.89-1.57; P=0.25; I2=2.8%; 11 studies with 1856 subjects).

CONCLUSIONS

Physician transfer was associated with a significant reduction in the mean of time interval between symptom onset and recanalization and increased odds for functional independence at 90 days with physician transfer compared with patient transfer among patients who undergo mechanical thrombectomy.

Network analysis of stroke systems of care in Korea

Background

The landscape of stroke care has shifted from stand-alone hospitals to cooperative networks among hospitals. Despite the importance of these networks, limited information exists on their characteristics and functional attributes.

Methods

We extracted patient-level data on acute stroke care and hospital connectivity by integrating national stroke audit data with reimbursement claims data. We then used this information to transform interhospital transfers into a network framework, where hospitals were designated as nodes and transfers as edges. Using the Louvain algorithm, we grouped densely connected hospitals into distinct stroke care communities. The quality and characteristics in given stroke communities were analysed, and their distinct types were derived using network parameters. The clinical implications of this network model were also explored.

Results

Over 6 months, 19 113 patients with acute ischaemic stroke initially presented to 1009 hospitals, with 3114 (16.3%) transferred to 246 stroke care hospitals. These connected hospitals formed 93 communities, with a median of 9 hospitals treating a median of 201 patients. Derived communities demonstrated a modularity of 0.904 , indicating a strong community structure, highly centralised around one or two hubs. Three distinct types of structures were identified: single-hub (n=60), double-hub (n=22) and hubless systems (n=11). The endovascular treatment rate was highest in double-hub systems, followed by single-hub systems, and was almost zero in hubless systems. The hubless communities were characterised by lower patient volumes, fewer hospitals, no hub hospital and no stroke unit.

Conclusions

This network analysis could quantify the national stroke care system and point out areas where the organisation and functionality of acute stroke care could be improved.

Optimized density and locations of stroke centers for improved cost effectiveness of mechanical thrombectomy in patients with acute ischemic stroke

BACKGROUND

Despite the proven cost effectiveness of mechanical thrombectomy (MT) in patients with acute ischemic stroke (AIS) due to large vessel occlusion, treatment within 6 hours from symptom onset remains inaccessible for many patients. We aimed to find the optimal number and location of treatment facilities with respect to the cost effectiveness of MT in patients with AIS, first by the most cost effective implementation of comprehensive stroke centers (CSCs), and second by the most cost effective addition of complementary thrombectomy capable stroke centers (TSCs).

METHODS

This study was based on nationwide observational data comprising 18 793 patients with suspected AIS potentially eligible for treatment with MT. The most cost effective solutions were attained by solving the p median facility location-allocation problem with the objective function of maximizing the incremental net monetary benefit (INMB) of MT compared with no MT in patients with AIS. Deterministic sensitivity analysis (DSA) was used as the basis of the results analysis.

RESULTS

The implementation strategy with seven CSCs produced the highest annual INMB per patient of all possible solutions in the base case scenario. The most cost effective implementation strategy of the extended scenario comprised seven CSCs and four TSCs. DSA revealed sensitivity to variability in MT rate and the maximum willingness to pay per quality adjusted life year gained.

CONCLUSION

The combination of optimization modeling and cost effectiveness analysis provides a powerful tool for configuring the extent and locations of CSCs (and TSCs). The most cost effective implementation of CSCs in Sweden entails 24/7 MT services at all seven university hospitals.

Higher Procedural Volumes Are Associated with Faster Treatment Times, Better Functional Outcomes, and Lower Mortality in Patients Undergoing Endovascular Treatment for Acute Ischemic Stroke

OBJECTIVE

We aimed to characterize the association of hospital procedural volumes with outcomes among acute ischemic stroke (AIS) patients undergoing endovascular therapy (EVT).

METHODS

This was a retrospective, observational cohort study using data prospectively collected from January 1, 2016 to December 31, 2019 in the Get with the Guidelines-Stroke registry. Participants were derived from a cohort of 60,727 AIS patients treated with EVT within 24 hours at 626 hospitals. The primary cohort excluded patients with pretreatment National Institutes of Health Stroke Scale (NIHSS) < 6, onset-to-treatment time > 6 hours, and interhospital transfers. There were 2 secondary cohorts: (1) the EVT metrics cohort excluded patients with missing data on time from door to arterial puncture and (2) the intravenous thrombolysis (IVT) metrics cohort only included patients receiving IVT ≤4.5 hours after onset.

RESULTS

The primary cohort (mean ± standard deviation age = 70.7 ± 14.8 years; 51.2% female; median [interquartile range] baseline NIHSS = 18.0 [13-22]; IVT use, 70.2%) comprised 21,209 patients across 595 hospitals. The EVT metrics cohort and IVT metrics cohort comprised 47,262 and 16,889 patients across 408 and 601 hospitals, respectively. Higher procedural volumes were significantly associated with higher odds (expressed as adjusted odds ratio [95% confidence interval] for every 10-case increase in volume) of discharge to home (1.03 [1.02-1.04]), functional independence at discharge (1.02 [1.01-1.04]), and lower rates of in-hospital mortality (0.96 [0.95-0.98]). All secondary measures were also associated with procedural volumes.

INTERPRETATION

Among AIS patients primarily presenting to EVT-capable hospitals (excluding those transferred from one facility to another and those suffering in-hospital strokes), EVT at hospitals with higher procedural volumes was associated with faster treatment times, better discharge outcomes, and lower rates of in-hospital mortality. ANN NEUROL 2023.

Relationships among hospital acute ischemic stroke volumes, hospital characteristics, and outcomes in the US

BACKGROUND AND OBJECTIVES

Prior research on volume-based patient outcomes related to acute ischemic stroke (AIS) have demonstrated contradictory results and fail to reflect recent advances in stroke care. We sought to examine contemporary relationships between hospital AIS volumes and outcomes.

METHODS

We used complete Medicare datasets in a retrospective cohort study using validated International Classification of Diseases Tenth Revision codes to identify patients admitted with AIS from January 1, 2016 through December 31, 2019. AIS volume was calculated as the total number of AIS admissions per hospital during the study period. We examined several hospital characteristics by AIS volume quartile. We performed adjusted logistic regressions testing associations of AIS volume quartiles with: inpatient mortality, receipt of tissue plasminogen activator (tPA) and endovascular therapy (ET), discharge home, and 30-day outpatient visit. We adjusted for sex, age, Charlson comorbidity score, teaching hospital status, MDI, hospital urban-rural designation, stroke certification status and ICU and neurologist availability at the hospital.

RESULTS

There were 952400 AIS admissions among 5084 US hospitals; AIS 4-year volume quartiles were: 1^st: 1-8 AIS admissions; 2^nd: 9-44; 3^rd: 45-237; 4^th: 238+. Highest quartile hospitals more often were stroke-certified (49.1% vs 8.7% in lowest quartile, p<0.0001), with ICU bed availability (19.8% vs 4.1%, p<0.0001) and with neurologist expertise (91.1% vs 3%, p<0.0001). In the highest AIS quartile (compared to the lowest quartile), there was lower inpatient mortality (odds ratio [OR] 0.71 [95%CI 0.57-0.87, p<0.0001]), lower 30-day mortality (0.55 [0.49-0.62], p<0.0001), greater receipt of tPA (6.60 [3.19-13.65], p<0.0001) and ET (16.43 [10.64-25.37], p<0.0001, and greater likelihood of discharge home (1.38 [1.22-1.56], p<0.0001). However, when the highest quartile hospitals were examined separately, higher volumes were associated with higher mortality despite higher rates of tPA and ET receipt.

CONCLUSIONS

High AIS-volume hospitals have greater utilization of acute stroke interventions, stroke certification and availability of neurologist and ICU care. These features likely play a role in the better outcomes observed at such centers, including inpatient and 30-day mortality and discharge home. However, the highest volume centers had higher mortality despite greater receipt of interventions. Further research is needed to better understand volume-outcome relationships in AIS to improve care at lower volume centers.

Recent trends in high-volume Medicare stroke thrombectomy provider characteristics

BACKGROUND

Intracranial mechanical thrombectomy (MT) is increasingly indicated for use in acute ischemic stroke patients. We analyzed recent trends in the characteristics and geographic distributions of physicians providing this service with frequency to Medicare beneficiaries.

METHODS

We linked public data sources to elucidate and visualize trends in high-volume MT providers between 2016 and 2019.

RESULTS

High-volume MT providers increased by 184% between 2016 and 2019. The number of neurosurgeons, neurologists, and radiologists in this physician population increased by 251%, 205%, and 139%, respectively. Male practitioners accounted for 96% of providers in the most recent year of analysis. International medical graduates accounted for roughly one-third of these physicians across all 4 years of analysis. As of 2019, the three states with the most high-volume MT providers were Florida, California, and Texas, accounting for 7%, 7%, and 6% of providers, respectively.

CONCLUSIONS

High-volume providers of MT services for Medicare beneficiaries represent a dynamic and rapidly expanding subset of physicians with diverse specialty backgrounds.

Mechanical Thrombectomy for Acute Ischemic Stroke

OBJECTIVE

Endovascular stroke therapy has greatly improved the ability to treat the deadliest and most disabling form of acute ischemic stroke. This article summarizes some of the recent innovations in this field and discusses likely future developments.

LATEST DEVELOPMENTS

At present, there is robust activity to improve all facets of care for patients with large vessel occlusion stroke, including better prehospital routing, more efficient in-hospital screening, expanding indications for thrombectomy eligibility, innovating novel thrombectomy devices, and improving the effects of recanalization on clinical outcomes. In addition, the integration of endovascular stroke therapy (EVT)-an emergent and frequently off-hours procedure that requires a specialized team of nurses, technologists, and physicians-into acute stroke care has transformed referral patterns, hospital accreditation pathways, and physician practices. The eligibility for the procedure will potentially continue to grow to include patients screened without advanced imaging, larger core infarcts, and more distal occlusions.

ESSENTIAL POINTS

In this review, we discuss the current state of EVT and its implications for practice, and present three cases that highlight some of the directions in which the field is moving.

Stroke thrombectomy volume, rather than stroke center accreditation status of hospitals, is associated with mortality and discharge disposition

BACKGROUND

Few studies have explored the association between stroke thrombectomy (ST) volume and hospital accreditation with clinical outcomes.

OBJECTIVE

To assess the association of ST case volume and accreditation status with in-hospital mortality and home discharge disposition using the national Medicare Provider Analysis and Review (MEDPAR) database.

METHODS

Rates of hospital mortality, home discharge disposition, and hospital stay were compared between accredited and non-accredited hospitals using 2017-2018 MEDPAR data. The association of annual ST case volume with mortality and home disposition was determined using Pearson's correlation. Median rate of mortality and number of ST cases at hospitals within the central quartiles were estimated.

RESULTS

A total of 29 355 cases were performed over 2 years at 847 US centers. Of these, 354 were accredited. There were no significant differences between accredited and non-accredited centers for hospital mortality (14.8% vs 14.5%, p=0.34) and home discharge (12.1% vs 12.0%, p=0.78). A significant positive correlation was observed between thrombectomy volume and home discharge (r=0.88; 95% CI 0.58 to 0.97, p=0.001). A significant negative relationship was found between thrombectomy volume and mortality (r=-0.86; 95% CI -0.97 to -0.49, p=0.002). Within the central quartiles, the median number of ST cases at hospitals with mortality was 24/year, and the median number of ST cases at hospitals with home discharge rate was 23/year.

CONCLUSION

A higher volume of ST cases was associated with lower mortality and higher home discharge rate. No significant differences in mortality and discharge disposition were found between accredited and non-accredited hospitals.

Influence of the interventionist's experience on outcomes of endovascular thrombectomy in acute ischemic stroke: results from the MR CLEAN Registry

BACKGROUND

The relationship between the interventionist's experience and outcomes of endovascular thrombectomy (EVT) for acute ischemic stroke of the anterior circulation, is unclear.

OBJECTIVE

To assess the effect of the interventionist's level of experience on clinical, imaging, and workflow outcomes. Secondly, to determine which of the three experience definitions is most strongly associated with these outcome measures.

METHODS

We analysed data from 2700 patients, included in the MR CLEAN Registry. We defined interventionist's experience as the number of procedures performed in the year preceding the intervention (EXPfreq), total number of procedures performed (EXPno), and years of experience (EXPyears). Our outcomes were the baseline-adjusted National Institutes of Health Stroke Scale (NIHSS) score at 24-48 hours post-EVT, recanalization (extended Thrombolysis in Cerebral Infarction (eTICI) score ≥2B), and procedural duration. We used multilevel regression models with interventionists as random intercept. For EXPfreq and EXPno results were expressed per 10 procedures.

RESULTS

Increased EXPfreq was associated with lower 24-48 hour NIHSS scores (adjusted (a)β:-0.46, 95% CI -0.70 to -0.21). EXPno and EXPyears were not associated with short-term neurological outcomes. Increased EXPfreq and EXPno were both associated with recanalization (aOR=1.20, 95% CI 1.11 to 1.31 and aOR=1.08, 95% CI 1.04 to 1.12, respectively), and increased EXPfreq, EXPno, and EXPyears were all associated with shorter procedure times (aβ:-3.08, 95% CI-4.32 to -1.84; aβ:-1.34, 95% CI-1.84 to -0.85; and aβ:-0.79, 95% CI-1.45 to -0.13, respectively).

CONCLUSIONS

Higher levels of interventionist's experience are associated with better outcomes after EVT, in particular when experience is defined as the number of patients treated in the preceding year. Every 20 procedures more per year is associated with approximately one NIHSS score point decrease, an increased probability for recanalization (aOR=1.44), and a 6-minute shorter procedure time.

Association between type of intervention center and outcomes after endovascular treatment for acute ischemic stroke: Results from the MR CLEAN Registry

Background:

Endovascular treatment (EVT) for acute ischemic stroke (AIS) is performed in intervention centers that provide the full range of neuro(endo)vascular care (level 1) and centers that only perform EVT for AIS (level 2). We compared outcomes between these center types and assessed whether differences in outcomes could be explained by center volume (CV).

Patients and methods:

We analyzed patients included in the MR CLEAN Registry (2014–2018), a registry of all EVT-treated patients in the Netherlands. Our primary outcome was the shift on the modified Rankin scale (mRS) after 90 days (ordinal regression). Secondary outcomes were the NIHSS 24–48 h post-EVT, door-to-groin time (DTGT), procedure time (linear regression), and recanalization (binary logistic regression). We compared outcomes between level 1 and 2 centers using multilevel regression models, with center as random intercept. We adjusted for relevant baseline factors, and in case of observed differences, we additionally adjusted for CV.

Results:

Of the 5144 patients 62% were treated in level 1 centers. We observed no significant differences between center types in mRS (adjusted(a)cOR: 0.79, 95% CI: 0.40 to 1.54), NIHSS (aβ: 0.31, 95% CI: −0.52 to 1.14), procedure duration (aβ: 0.88, 95% CI: −5.21 to 6.97), or DTGT (aβ: 4.24, 95% CI: −7.09 to 15.57). The probability for recanalization was higher in level 1 centers compared to level 2 centers (aOR 1.60, 95% CI: 1.10 to 2.33), and this difference probably depended on CV.

Conclusions:

We found no significant differences, that were independent of CV, in the outcomes of EVT for AIS between level 1 and level 2 intervention centers.

Developing and predicting of early mortality after endovascular thrombectomy in patients with acute ischemic stroke

BACKGROUND

Stroke is one of the leading causes of mortality across the world. However, there is a paucity of information regarding mortality rates and associated risk factors in patients with acute ischemic stroke (AIS) undergoing endovascular thrombectomy (EVT). In this study, we aimed to clarify these issues and analyzed previous publications related to mortality in patients treated with EVT.

METHODS

We analyzed the survival of 245 consecutive patients treated with mechanical thrombectomy for AIS for which mortality information was obtained. Early mortality was defined as death occurring during hospitalization after EVT or within 7 days following hospital discharge from the stroke event.

RESULTS

Early mortality occurred in 22.8% of cases in this cohort. Recanalization status (modified thrombolysis in cerebral infarction, mTICI) (p = 0.002), National Institute of Health Stroke Scale Score (NIHSS) score 24-h after EVT (p < 0.001) and symptomatic intracerebral hemorrhage (sICH) (p < 0.001) were independently associated with early mortality. Age, sex, cardiovascular risk factors, NIHSS score pre-treatment, Alberta Stroke Program Early CT Score (ASPECTS), stroke subtype, site of arterial occlusion and timing form onset to recanalization did not have an independent influence on survival. Non-survivors had a shorter hospitalization (p < 0.001) but higher costs related to their hospitalization and outpatient care.

CONCLUSION

The recanalization status, NIHSS score 24-h after EVT and sICH were predictors of early mortality in AIS patients treated with EVT.

Annual Case Volume and One-Year Mortality for Endovascular Treatment in Acute Ischemic Stroke

BACKGROUND

The association between endovascular treatment (EVT) case volume per hospital and clinical outcomes has been reported, but the exact volume threshold has not been determined. This study aimed to examine the case volume threshold in this context.

METHODS

National audit data on the quality of acute stroke care in patients admitted via emergency department, within 7 days of onset, in hospitals that treated ≥ 10 stroke cases during the audit period were analyzed. Ischemic stroke cases treated with EVT during the last three audits (2013, 2014, and 2016) were selected for the analysis. Annual EVT case volume per hospital was estimated and analyzed as a continuous and a categorical variable (in quartiles). The primary outcome measure was 1-year mortality as a surrogate of 3-month functional outcome. As post-hoc sensitivity analysis, replication of the study results was examined using the 2018 audit data.

RESULTS

We analyzed 1,746 ischemic stroke cases treated with EVT in 120 acute care hospitals. The median annual EVT case volume was 12.0 cases per hospital, and mortality rates at 1 month, 3 months, and 1 year were 12.7%, 16.6%, and 23.3%, respectively. Q3 and Q4 had 33% lower odds of 1-year mortality than Q1. Adjustments were made for predetermined confounders. Annual EVT case volume cut-off value for 1-year mortality was 15 cases per year (P < 0.02). The same cut-off value was replicated in the sensitivity analysis.

CONCLUSION

Annual EVT case volume was associated with 1-year mortality. The volume threshold per hospital was 15 cases per year.

Neutrophil-Lymphocyte ratio is associated with poor clinical outcome after mechanical thrombectomy in stroke in patients with COVID-19

Background

The neutrophil–lymphocyte ratio (NLR) is emerging as an important biomarker of acute physiologic stress in a myriad of medical conditions, and is a confirmed poor prognostic indicator in COVID-19.

Objective

We sought to describe the role of NLR in predicting poor outcome in COVID-19 patients undergoing mechanical thrombectomy for acute ischemic stroke.

Methods

We analyzed NLR in COVID-19 patients with large vessel occlusion (LVO) strokes enrolled into an international 12-center retrospective study of laboratory-confirmed COVID-19, consecutively admitted between March 1, 2020 and May 1, 2020. Increased NLR was defined as ≥7.2. Logistic regression models were generated.

Results

Incidence of LVO stroke was 38/6698 (.57%). Mean age of patients was 62 years (range 27–87), and mortality rate was 30%. Age, sex, and ethnicity were not predictive of mortality. Elevated NLR and poor vessel recanalization (Thrombolysis in Cerebral Infarction (TICI) score of 1 or 2a) synergistically predicted poor outcome (likelihood ratio 11.65, p  =  .003). Patients with NLR > 7.2 were 6.8 times more likely to die (OR 6.8, CI95% 1.2–38.6, p  =  .03) and almost 8 times more likely to require prolonged invasive mechanical ventilation (OR 7.8, CI95% 1.2–52.4, p  =  .03). In a multivariate analysis, NLR > 7.2 predicted poor outcome even when controlling for the effect of low TICI score on poor outcome (NLR p  =  .043, TICI p  =  .070).

Conclusions

We show elevated NLR in LVO patients with COVID-19 portends significantly worse outcomes and increased mortality regardless of recanalization status. Severe neuro-inflammatory stress response related to COVID-19 may negate the potential benefits of successful thrombectomy.

Advanced imaging in acute ischemic stroke: an updated guide to the hub-and-spoke hospitals

PURPOSE OF REVIEW

The purpose of this review is to summarize the role of the hub-and-spoke system in acute stroke care, highlight the role of advanced imaging and discuss emerging concepts and trials relevant to the hub-and-spoke model.

RECENT FINDINGS

The advent of advanced stroke multimodal imaging has provided increased treatment options for patients, particularly in rural and regional areas. When used in the hub-and-spoke model, advanced imaging can help facilitate and triage transfers, appropriately select patients for acute therapy and treat patients who may otherwise be ineligible based on traditional time metrics.Recent, ongoing trials in this area may lead to an even greater range of patients being eligible for acute reperfusion therapy, including mild strokes and patients with large core infarct volumes.

SUMMARY

Integration of advanced imaging into a hub-and-spoke system, when complemented with other systems including telemedicine, improves access to acute stroke care for patients in regional and rural areas.