Emerging temporal trends in tissue plasminogen activator use: Results from the BASIC project

Changes Over Time in Short-Term Stroke Outcomes by Race-Ethnicity

OBJECTIVES

The objective of this study was to quantify trends (2008-2019) in stroke outcomes by race-ethnicity.

METHODS

Patients with ischemic stroke from a population-based study were interviewed at 90 days to assess outcomes. Linear regression with multiple imputation and inverse probability weighting was used to model trends.

RESULTS

The median age was 66 years (n = 1,449); 61% were Mexican American (MA). QOL remained stable with no race-ethnic difference in trends (p for time*race-ethnicity interaction = 0.81). Neurologic outcomes improved for MA (p < 0.01) but not non-Hispanic White (NHW) persons with stroke (p = 0.23) with no race-ethnic difference in trends (p for interaction = 0.23). For functional outcomes, trends were stable and then improved in MA persons with stroke (p for interaction = 0.01), whereas trends were stable in NHW persons with stroke (p = 0.52). For cognitive outcomes, there was little change in NHW persons with stroke (p = 0.50); in MA persons with stroke, there was improvement followed by decline and then improvement (p = 0.03). No race-ethnic differences in trends in functional (p for interaction = 0.51) or cognitive (p for interaction = 0.21) outcomes were noted.

DISCUSSION

Outcome improvements were noted in MA but not NHW persons with stroke; race-ethnic differences were not present in 2019. Understanding factors contributing to favorable trends in MA persons may be informative for improving outcomes in all persons.

Impact of presenting stroke severity and thrombolysis on outcomes following urgent carotid interventions

BACKGROUND

Carotid interventions are increasingly performed in select patients following acute stroke. We aimed to determine the effects of presenting stroke severity (National Institutes of Health Stroke Scale [NIHSS]) and use of systemic thrombolysis (tissue plasminogen activator [tPA]) on discharge neurological outcomes (modified Rankin scale [mRS]) after urgent carotid endarterectomy (uCEA) and urgent carotid artery stenting (uCAS).

METHODS

Patients undergoing uCEA/uCAS at a tertiary Comprehensive Stroke Center (January 2015 to May 2022) were divided into two cohorts: (1) no thrombolysis (uCEA/uCAS only) and (2) use of thrombolysis before the carotid intervention (tPA + uCEA/uCAS). Outcomes were discharge mRS and 30-day complications. Regression models were used to determine an association between tPA use and presenting stroke severity (NIHSS) and discharge neurological outcomes (mRS).

RESULTS

Two hundred thirty-eight patients underwent uCEA/uCAS (uCEA/uCAS only, n = 186; tPA + uCEA/uCAS, n = 52) over 7 years. In the thrombolysis cohort compared with the uCEA/uCAS only cohort, the mean presenting stroke severity was higher (NIHSS = 7.6 vs 3.8; P = .001), and more patients presented with moderate to severe strokes (57.7% vs 30.2% with NIHSS >4). The 30-day stroke, death, and myocardial infarction rates in the uCEA/uCAS only vs tPA + uCEA/uCAS were 8.1% vs 11.5% (P = .416), 0% vs 9.6% (P < .001), and 0.5% vs 1.9% (P = .39), respectively. The 30-day stroke/hemorrhagic conversion and myocardial infarction rates did not differ with tPA use; however, the difference in deaths was significantly higher in the tPA + uCEA/uCAS cohort (P < .001). There was no difference in neurological functional outcome with or without thrombolysis use (mean mRS, 2.1 vs 1.7; P = .061). For both minor strokes (NIHSS ≤4 vs NIHSS >4: relative risk, 1.58 vs 1.58, tPA vs no tPA, respectively, P = .997) and moderate strokes (NIHSS ≤10 vs NIHSS >10: relative risk, 1.94 vs 2.08, tPA vs no tPA, respectively; P = .891), the likelihood of discharge functional independence (mRS score of ≤2) was not influenced by tPA.

CONCLUSIONS

Patients with a higher presenting stroke severity (NIHSS) had worse neurological functional outcomes (mRS). Patients presenting with minor and moderate strokes were more likely to have discharge neurological functional independence (mRS of ≤2), regardless of whether they received tPA or not. Overall, presenting NIHSS is predictive of discharge neurological functional autonomy and is not influenced by the use of thrombolysis.

Outcomes in the Year After First-Ever Ischemic Stroke in a Bi-Ethnic Population

OBJECTIVE

To investigate stroke outcomes at 3, 6, and 12 months post-stroke overall and by ethnicity in a population-based, longitudinal study.

METHODS

First-ever ischemic strokes (2014-2019, n = 1,332) among Mexican American persons (n = 807) and non-Hispanic white persons (n = 525) were identified from the Brain Attack Surveillance in Corpus Christi Project. Data were collected from patient or proxy interviews (baseline, 3, 6, and 12 months post-stroke) and medical records, including functional (activities of daily living/instrumental activities of daily living score), neurological (National Institutes of Health Stroke Scale), cognitive (Modified Mini-Mental State Examination), and quality of life (QOL) outcomes (12-domain Stroke-specific Quality of Life scale). Outcome trajectories were analyzed using multivariable adjusted linear models, with generalized estimating equations to account for within-subject correlations; interactions between ethnicity and time were included to investigate ethnic differences in outcomes.

RESULTS

The median age was 67 years (interquartile range 58,78), 48.5% were women, and 60.6% were Mexican American persons. For all outcomes, significant improvement was seen between 3 and 6 months (p < 0.05 for all), with stability between 6 and 12 months. Mexican American persons had significantly worse outcomes compared with non-Hispanic white persons at all time points (3, 6, and 12 months), with the exception of the National Institutes of Health Stroke Scale, which did not differ by ethnicity at 6 and 12 months, and the average change in outcomes did not vary significantly by ethnicity.

INTERPRETATION

Outcomes were at their worst at 3 months post-stroke, and ethnic disparities were already present, suggesting the need for early assessment and strategies to improve outcomes and possibly reduce disparities. ANN NEUROL 2023;93:348-356.

The impact of a comprehensive national policy on improving acute stroke patient care in Lithuania

Introduction:

Reperfusion therapy (RT) is a mainstay treatment for acute ischemic stroke (AIS). We aimed to evaluate the impact of a comprehensive national policy (CNP) to improve access to RT for AIS patients across Lithuania.

Patients and methods:

Aggregated anonymized data on AIS cases treated in Lithuanian hospitals between 2006 and 2019 were retrospectively obtained from the Institute of Hygiene and the Stroke Integrated Care Management Committee. Through an interrupted time series analysis, we examined the trends in AIS hospital admissions, RT, and in-hospital case fatality rates prior to the enactment of CNP in 2014, changes immediately after the intervention, and differences in trends between the pre- and post-intervention periods. Mean yearly door-to-needle times were calculated post-intervention.

Results:

114,436 cases were treated for AIS in Lithuanian hospitals before, and 65,084 after the government intervention. We observed a significant decreasing post-intervention trend change in AIS hospital admission rate per 100,000 population (regression coefficient ± standard error: β = –16.47 ± 3.95, p = 0.002) and an increasing trend change in the proportion of AIS patients who received reperfusion treatment: intravenous thrombolysis (β = 1.42 ± 0.96, p < 0.001) and endovascular therapy (β = 0.85 ± 0.05, p < 0.001). The proportion of patients treated in stroke centers increased immediately after the intervention (β = 4.95 ± 1.14, p = 0.001), but the long-term post-intervention trend did not change. In addition, there was a significant decreasing trend in all cause in-hospital case fatality rate within primary and comprehensive stroke centers after the intervention (β = –0.60 ± 0.18, p = 0.008) despite its prompt initial immediate increase (β = 1.68 ± 0.73, p = 0.043). The mean countrywide door-to-needle time decreased from 68 min in 2014 to 43 min in 2019.

Conclusion:

The comprehensive national stroke patient care policy could be associated with an immediate increase in stroke center treatment rate, increased access to RT, and improved stroke care performance measures.

Lessons Learned From the Historical Trends on Thrombolysis Use for Acute Ischemic Stroke Among Medicare Beneficiaries in the United States

Background

The most recent time trends on intravenous thrombolysis (IVT) utilization for acute ischemic stroke was reported in 2011 using the Get with the Guidelines. Our objectives are to assess and validate the change in IVT utilization through 2014 in a national sample of Medicare beneficiaries and to examine the effect of patient, stroke center designation, and geography on IVT utilization.

Methods

We built a comprehensive national stroke registry by combining patient-level, stroke center status, and geographical characteristics, using multiple data sources. Using multiple national administrative databases from 2007 to 2014, we generated a mixed-effect logistic regression model to characterize the independent associations of patient, hospital, and geographical characteristics with IVT in 2014.

Results

Use of IVT increased consistently from 2.8% in 2007 to 7.7% in 2014, P < 0.001. Between group differences persisted, with lower odds of use in patients who were ≥86 years (aOR 0.74, 95% CI 0.65-0.83), Black (aOR 0.73, 95% CI 0.61-0.87), or treated at a rural hospital (aOR 0.88, 95% CI 0.77-1.00). Higher odds of use were observed in patients who arrived by ambulance (aOR 2.67, 95% CI 2.38-3.00), were treated at a hospital certified as a stroke center (aOR 1.96, 95% CI 1.68-2.29), or were treated at hospitals located in the most socioeconomically advantaged areas (aOR 1.27, 95% CI 1.05-1.54).

Conclusions

Between 2007 and 2014, the frequency of IVT for patients with acute ischemic stroke increased substantially, though differences persisted in the form of less frequent treatment associated with certain characteristics. These findings can inform ongoing efforts to optimize the delivery of IVT to all AIS patients nationwide.

Community Intent to Activate Emergency Medical Services May Be Associated with Regional tPA Treatment

INTRODUCTION

Acute stroke treatments are underutilized in the USA. Enhancing stroke preparedness, the recognition of stroke symptoms, and intent to call emergency medical services (EMS) could reduce delay in hospital arrival thereby increasing eligibility for time-sensitive stroke treatments. Whether higher stroke preparedness is associated with higher tissue plasminogen activator (tPA) treatment rates is however uncertain. We therefore set out to determine the contribution of stroke preparedness to regional variation in tPA treatment.

METHODS

The region was defined by hospital service area (HSA). Stroke preparedness was determined by using Behavioral Risk Factor Surveillance System survey questions assessing stroke symptom recognition and intent to call 911 in response to a stroke. We used Medicare data to determine the percentage of tPA-treated hospitalized stroke patients in 2007, 2009, and 2011, adjusting for number of stroke hospitalizations in each HSA (primary outcome). We performed multivariate linear regression to estimate the association of regional stroke preparedness on log-transformed tPA treatment rates controlling for demographic, EMS, and hospital characteristics.

RESULTS

The adjusted percentage of stroke patients receiving tPA ranged from 1.4% (MIN) to 11.3% (MAX) of stroke/TIA hospitalizations. Across HSAs, a median (IQR) of 86% (81-90%) of responses to a witnessed stroke indicated intent to call 911, and a median (IQR) of 4.4 (4.2-4.6) out of 6 stroke symptoms was recognized. Every 1% increase in an HSA's intent to call 911 was associated with a 0.44% increase in adjusted tPA treatment rate (p = 0.05). Lower accuracy of recognition of stroke symptoms was associated with higher adjusted tPA treatment rates (p = 0.05).

CONCLUSIONS

There was little regional variation in intent to call EMS and stroke symptom recognition. Intent to call EMS and stroke symptom recognition are modest contributors to regional variation in tPA treatment.

Trends of Acute Ischemic Stroke Reperfusion Therapies from 2012 to 2016 in the United States

BACKGROUND

American Heart Association/American Stroke Association guidelines recommend endovascular stroke therapy (EST) with recombinant tissue plasminogen activator (rt-PA) for eligible patients in acute ischemic stroke (AIS). Using the National Inpatient Sample database, we evaluated trends in treatment with rt-PA and EST for AIS and their outcomes.

METHODS

This is a cross-sectional observational study of patients with AIS admitted in US hospitals from 2012 to 2016. Patients were grouped into those who received rt-PA alone, EST alone, and rtPA+EST. Survey statistical procedures were performed. Multivariable regression analysis with pairwise comparisons of each treatment group with no treatment group was performed for discharge outcomes.

RESULTS

The study included 2,290,520 patients with AIS with the mean age of 70.46 years. Treatment rates increased from 2012 to 2016 for rt-PA by 7% per year (5.86%-7.67%, odds ratio [OR] = 1.07, 95% confidence interval [CI]: 1.05-1.08) and EST by 38% per year (0.55%-1.75%, OR = 1.38, 95% CI: 1.31-1.45) but not rt-PA+EST (0.54%-0.57%, OR = 1.04, 95% CI: 0.99-1.08). The mean length of stay reduced from 2012 to 2016 for rt-PA (6.07-4.91 days, P < 0.0001) and rt-PA+EST (9.19-7.10 days, P = 0.0067) but not for EST (9.61-8.51 days, P = 0.5074). The odds of patients discharged home increased by 8%, 9%, and 15% among patients who received rt-PA alone, EST alone, and rt-PA+EST, respectively, compared with no treatment group.

CONCLUSION

The utilization of rt-PA alone and EST alone increased but that of rt-PA+EST remained unchanged from 2012 to 2016 in the National Inpatient Sample.

Distributional Validity and Prognostic Power of the National Institutes of Health Stroke Scale in US Administrative Claims Data

Importance

Comparative assessment of acute ischemic stroke care quality provided by hospitals in the United States has been hampered by the unavailability of the National Institutes of Health Stroke Scale (NIHSS) in administrative data sets, preventing adequate adjustment for variations in patient case-mix risk. In response to stakeholder concerns, the US Centers for Medicare & Medicaid Services in 2016 implemented optional reporting of NIHSS scores.

Objective

To analyze the distributional, convergent, and predictive validity of nationally submitted NIHSS values in the National Inpatient Sample.

Design, Setting, and Participants

This population-based retrospective cross-sectional study took place from October 1 to December 31, 2016. The nationally representative sample included US adults who had ischemic stroke hospitalizations during the first calendar quarter in which optional NIHSS reporting was implemented. Analysis began September 2019.

Main Outcomes and Measures

Distribution of NIHSS scores, functional independence at discharge, inpatient mortality, and administrative reporting of NIHSS.

Results

Among 154 165 ischemic stroke hospitalizations during the first 3 months of the reporting policy, NIHSS scores were reported in 21 685 patients (14%) (10 925 women [50.4%]; median [interquartile range] age, 72 [61-82] years). Median (interquartile range) NIHSS score was 4 (2-11), and frequency of severity categories included absent (NIHSS score, 0) in 2080 patients (9.6%), minor (NIHSS score, 1-4) in 8760 patients (40.4%), and severe (NIHSS score, 21-42) in 1930 patients (8.9%). National Institutes of Health Stroke Scale score of 10 or more, an indicator of possible large vessel occlusions, was present in 6290 patients (29%). Presenting NIHSS score was higher in very elderly patients (age ≥80 y) and women and also in patients receiving endovascular thrombectomy vs intravenous thrombolysis alone vs no reperfusion therapy (median [interquartile range], 17 [12-22] vs 6 [4-12] vs 4 [2-9], respectively) (P < .001). National Institutes of Health Stroke Scale scores were similarly higher for discharge outcomes of mortality vs discharge to skilled nursing facility vs discharge home (median [interquartile range], 19 [12-25] vs 7 [3-15] vs 2 [1-5], respectively) (P < .001). Likelihood of NIHSS scores being reported independently increased with interfacility transfer, receipt of acute reperfusion therapies, larger hospital size, academic centers, and region other than the West.

Conclusions and Relevance

In the initial national optional reporting period in the United States, NIHSS scores were reported in nearly 1 in 7 ischemic stroke hospitalizations. The distribution of NIHSS scores was similar to that from narrow population-based studies and registries, and NIHSS scores were powerfully associated with discharge outcome, supporting the validity and potential to aid care quality assessment.

Nationwide temporal trend analysis of reperfusion therapy utilization and mortality in acute ischemic stroke patients in Japan

This study aimed to elucidate nationwide trends in reperfusion therapy utilization and subsequent 30-day mortality in acute ischemic stroke patients in Japan. The analysis focused on intravenous recombinant tissue plasminogen activator (IV rt-PA) and endovascular thrombectomy (EVT). Using health insurance claims data, we calculated the age- and sex-adjusted monthly number of acute ischemic stroke patients who received IV rt-PA and/or EVT in Japan from April 2010 to March 2016, and investigated the 30-day all-cause mortality rates after undergoing these therapies. Through an interrupted time-series analysis, we examined the: (1).. trends prior to extension of the IV rt-PA therapeutic time window from 3 hours to 4.5 hours in September 2012, (2).. changes that occurred immediately after the extension, and (3).. differences in trends between the pre- and post-extension periods. During the study period, 69,920 patients with acute ischemic stroke (mean age ± standard deviation: 74.9 ± 12.0 years; 41.4% women) received IV rt-PA and/or EVT. The age- and sex-adjusted number of patients receiving IV rt-PA monotherapy increased immediately after the time window extension (<rk-italic > P < .001), but did not change during the pre- (P = .90) and post-extension (P = .58) periods. In contrast, the number of patients receiving EVT with or without IV rt-PA continuously increased during the pre-extension period (P < .001), and further increased during the post-extension period (P <.001); however, this number decreased immediately after the extension (P < .001). There were no significant changes in 30-day all-cause mortality during the pre- (P = .40) and post-extension (P = .64) periods, as well as immediately after the extension (P = .53). The extension of the IV rt-PA therapeutic time window and progressively widespread use of EVT in Japan have increased the number of acute ischemic stroke patients eligible for reperfusion therapy. These trends were not accompanied by a higher risk of post-reperfusion mortality.

Temporal trends and geographical disparities in comprehensive stroke centre capabilities in Japan from 2010 to 2018

OBJECTIVES

Comprehensive stroke centre (CSC) capabilities are associated with reduced in-hospital mortality due to acute stroke. However, it remains unclear whether there are improving trends in the CSC capabilities or how hospital-related factors determine quality improvement. This study examined whether CSC capabilities changed in Japan between 2010 and 2018 and and whether any changes were influenced by hospital characteristics.

DESIGN

A hospital-based cross-sectional study.

SETTING

We sent out questionnaires to the training institutions of the Japan Neurosurgical Society and Japan Stroke Society in 2010, 2014 and 2018.

PARTICIPANTS

749 hospitals in 2010, 532 hospitals in 2014 and 786 hospitals in 2018 participated in the J-ASPECT study, a nationwide survey of acute stroke care capacity for proper designation of a comprehensive stroke centre in Japan.

MAIN OUTCOME MEASURES

CSC capabilities were assessed using the validated scoring system (CSC score: 1-25 points) in 2010, 2014 and 2018 survey. The effect of hospital characteristics was examined using multiple logistic regression analysis.

RESULTS

Among the 323 hospitals that responded to all surveys, the implementation of 13 recommended items increased. The CSC score (median and IQR) was 16 (13-19), 18 (14-20) and 19 (15-21) for 2010, 2014 and 2018, respectively (p<0.001). There was a ≥20% increase in six items (eg, endovascular physicians, stroke unit and interventional coverage 24/7), and a ≤20% decrease in community education. A lower baseline CSC score (OR: 0.82, 95% CI 0.75 to 0.9), the number of beds≥500 (OR: 3.9, 95% CI 1.2 to 13.0) and the number of stroke physicians (7-9) (OR: 2.6, 95% CI 1.1 to 6.3) were associated with improved CSC capabilities, independent of geographical location.

CONCLUSIONS

There was a significant improvement in CSC capabilities between 2010 and 2018, which was mainly related to the availability of endovascular treatment and multidisciplinary care. Our findings may be useful to determine which hospitals should be targeted to improve CSC capabilities in a defined area.

Sex differences in IV thrombolysis treatment for acute ischemic stroke

Objective

A prior meta-analysis of reports published between 2000 and 2008 found that women were 30% less likely to receive IV recombinant tissue plasminogen activator (rtPA) treatment for stroke than men; we updated this meta-analysis to determine if this sex difference persisted.

Methods

We identified studies that reported sex-specific IV rtPA treatment rates for acute ischemic stroke published between 2008 and 2018. Eligible studies included representative populations of patients with ischemic stroke from hospital-based, registry-based, or administrative data. Random effects odds ratios (ORs) were generated to quantify sex differences.

Results

Twenty-four eligible studies were identified during this 10-year period. The summary unadjusted OR based on 17 studies with data on all ischemic stroke patients was 0.87 (95% confidence interval [CI], 0.82–0.93), indicating that women had 13% lower odds of receiving IV rtPA treatment than men. However, substantial between-study variability existed. Lower treatment odds in women were also observed in 7 studies that provided data on the subgroup of patients eligible for IV rtPA treatment, although the summary OR of 0.95 (95% CI, 0.88–1.02) was not statistically significant. Examination of time trends across 33 studies published between 2000 and 2018 found evidence that the sex difference had narrowed in more recent years.

Conclusions

Although there is considerable variability in the findings of individual studies, pooled data from recent studies show that women with acute stroke are less likely to be treated with IV thrombolysis compared with men. However, the size of this difference has narrowed compared to studies published before 2008.

National trends in outcomes of ischemic stroke and prognostic influence of stroke center capability in Japan, 2010-2016

BACKGROUND

Limited national-level information on temporal trends in comprehensive stroke center capabilities and their effects on acute ischemic stroke patients exists.

AIMS

To examine trends in in-hospital outcomes of acute ischemic stroke patients and the prognostic influence of temporal changes in comprehensive stroke center capabilities in Japan.

METHODS

This retrospective study used the J-ASPECT Diagnosis Procedure Combination database and identified 372,978 acute ischemic stroke patients hospitalized in 650 institutions between 2010 and 2016. Temporal trends in patient outcomes and recombinant tissue plasminogen activator (rt-PA) and mechanical thrombectomy usage were examined. Facility comprehensive stroke center capabilities were assessed using a validated scoring system (comprehensive stroke center score: 1-25 points) in 2010 and 2014. The prognostic influence of temporal comprehensive stroke center score changes on in-hospital mortality and poor outcomes (modified Rankin Scale: 3-6) at discharge were examined using hierarchical logistic regression models.

RESULTS

Over time, stroke severity at admission decreased, whereas median age, sex ratio, and comorbidities remained stable. The median comprehensive stroke center score increased from 16 to 17 points. After adjusting for age, sex, comorbidities, consciousness level, and facility comprehensive stroke center score, proportion of in-hospital mortality and poor outcomes at discharge decreased (from 7.6% to 5.0%, and from 48.7% to 43.1%, respectively). The preceding comprehensive stroke center score increase (in 2010-2014) was independently associated with reduced in-hospital mortality and poor outcomes, and increased rt-PA and mechanical thrombectomy use (odds ratio (95% confidence interval): 0.97 (0.95-0.99), 0.97 (0.95-0.998), 1.07 (1.04-1.10), and 1.21 (1.14-1.28), respectively).

CONCLUSIONS

This nationwide study revealed six-year trends in better patient outcomes and increased use of rt-PA and mechanical thrombectomy in acute ischemic stroke. In addition to lesser stroke severity, preceding improvement of comprehensive stroke center capabilities was an independent factor associated with such trends, suggesting importance of comprehensive stroke center capabilities as a prognostic indicator of acute stroke care.

Temporal Trends in Clinical Characteristics and Door-to-Needle Time in Patients Receiving Intravenous Tissue Plasminogen Activator: A Retrospective Study of 4 Hospitals in Japan

BACKGROUND

Intravenous recombinant tissue plasminogen activator (rt-PA) has become a common treatment for acute ischemic stroke and has highly time-dependent benefits. We aimed to clarify temporal trends regarding the frequency and characteristics of patients receiving rt-PA and explore factors associated with door-to-needle time (DNT) in Japanese emergency hospitals.

METHODS

Consecutive patients who received intravenous rt-PA for acute ischemic stroke from October 2005 to December 2015 were retrospectively registered from 4 hospitals. Temporal trends in the frequency and characteristics of patients receiving rt-PA and factors associated with DNT were investigated.

RESULTS

A total of 750 patients, including 688 (420 men, median 75 years old) with out-of-hospital stroke, were registered. The frequency of patients receiving intravenous rt-PA for acute ischemic stroke continuously increased from 1.8% in 2005 to 9.5% in 2015. The proportion of patients who were elderly or had prestroke disability increased over time, while pretreatment stroke severity declined. The DNT gradually decreased (median 105 minutes in 2005, 61 minutes in 2015). According to multivariate regression analysis with correction for multiple comparisons, activation of a code stroke system (standardized partial regression coefficient (β) -.50, P < .001, q < .001), onset-to-door time (β -.15, P < .001, q < .001), pretreatment with antithrombotic agents (β .12, P < .001, q = .001), and year of treatment (β .11, P = .007, q = .011) were associated with DNT.

CONCLUSIONS

Intravenous rt-PA was widely adopted in Japanese emergency hospitals. Characteristics of patients receiving intravenous rt-PA have changed over the past decade. Several factors, including the year of treatment, were associated with DNT, which has shortened over time.