Yu Wei Chen

Get With The Guidelines-Stroke Performance Indicators: Surveillance of Stroke Care in the Taiwan Stroke Registry: Get With The Guidelines-Stroke in Taiwan

Background— Stroke is a leading cause of death around the world. Improving the quality of stroke care is a global priority, despite the diverse healthcare economies across nations. The American Heart Association/American Stroke Association Get With the Guidelines-Stroke program (GWTG-Stroke) has improved the quality of stroke care in 790 US academic and community hospitals, with broad implications for the rest of the country. The generalizability of GWTG-Stroke across national and economic boundaries remains to be tested. The Taiwan Stroke Registry, with 30 599 stroke admissions between 2006 and 2008, was used to assess the applicability of GWTG-Stroke in Taiwan, which spends ≈1/10 of what the United States does in medical costs per new or recurrent stroke. Methods and Results— Taiwan Stroke Registry, sponsored by the Taiwan Department of Health, engages 39 academic and community hospitals and covers the entire country with 4 steps of quality control to ensure the reliability of entered data. Five GWTG-Stroke performance measures and 1 safety indicator are applicable to assess Taiwan Stroke Registry quality of stroke care. Demographic and outcome figures are comparable between GWTG-Stroke and Taiwan Stroke Registry. Two indicators (early and discharge antithrombotics) are close to GWTG-Stroke standards, while 3 other indicators (intravenous tissue plasminogen activator, anticoagulation for atrial fibrillation, lipid-lowering medication) and 1 safety indicator fall behind. Preliminary analysis shows that compliance with selected GWTG-Stroke guidelines is associated with better outcomes. Conclusions— Results suggest that GWTG-Stroke performance measures, with modification for ethnic factors, can become global standards across national and economic boundaries for assessing and improving quality of stroke care and outcomes. GWTG-Stroke can be incorporated into ongoing stroke registries across nations.

Comparison of Risk-scoring Systems in Predicting Symptomatic Intracerebral Hemorrhage After Intravenous Thrombolysis

Background and Purpose— Various risk score models have been developed to predict symptomatic intracerebral hemorrhage (SICH) after intravenous thrombolysis for acute ischemic stroke. In this study, we aimed to determine the prediction performance of these risk scores in a Taiwanese population Methods— Prospectively collected data from 4 hospitals were used to calculate probability of SICH with the scores developed by Cucchiara et al, the Hemorrhage After Thrombolysis (HAT) score, the Safe Implementation of Thrombolysis in Stroke-SICH risk score, the Glucose Race Age Sex Pressure Stroke Severity score, and the Stroke Prognostication using Age and National Institutes of Health Stroke Scale-100 index. We used logistic regression to evaluate the effectiveness of each risk model in predicting SICH and the c statistic to assess performance. Results— A total of 548 patients were included. The rates of SICH were 7.3% by the National Institute of Neurological Diseases and Stroke definition, 5.3% by the European-Australasian Cooperative Acute Stroke Study II definition, and 3.5% by the Safe Implementation of Thrombolysis in Stroke-Monitoring Study definition. The Cucchiara score, the HAT score, and the Safe Implementation of Thrombolysis in Stroke-SICH risk score were significant predictors of SICH for all 3 definitions, whereas the Glucose Race Age Sex Pressure Stroke Severity score and the Stroke Prognostication using Age and National Institutes of Health Stroke Scale-100 index predicted well only for 1 or 2 definitions of SICH. The c statistic was highest for the HAT score (range, 0.69–0.73) across the definitions of SICH. Conclusions— The Cucchiara score, the HAT score, and the Safe Implementation of Thrombolysis in Stroke-SICH risk score predicted SICH reasonably well regardless of which SICH definition was used. However, only the HAT score had an acceptable discriminatory ability.

Developing a stroke severity index based on administrative data was feasible using data mining techniques

OBJECTIVES Case-mix adjustment is difficult for stroke outcome studies using administrative data. However, relevant prescription, laboratory, procedure, and service claims might be surrogates for stroke severity. This study proposes a method for developing a stroke severity index (SSI) by using administrative data. STUDY DESIGN AND SETTING We identified 3,577 patients with acute ischemic stroke from a hospital-based registry and analyzed claims data with plenty of features. Stroke severity was measured using the National Institutes of Health Stroke Scale (NIHSS). We used two data mining methods and conventional multiple linear regression (MLR) to develop prediction models, comparing the model performance according to the Pearson correlation coefficient between the SSI and the NIHSS. We validated these models in four independent cohorts by using hospital-based registry data linked to a nationwide administrative database. RESULTS We identified seven predictive features and developed three models. The k-nearest neighbor model (correlation coefficient, 0.743; 95% confidence interval: 0.737, 0.749) performed slightly better than the MLR model (0.742; 0.736, 0.747), followed by the regression tree model (0.737; 0.731, 0.742). In the validation cohorts, the correlation coefficients were between 0.677 and 0.725 for all three models. CONCLUSION The claims-based SSI enables adjusting for disease severity in stroke studies using administrative data.

Validation of algorithms to identify stroke risk factors in patients with acute ischemic stroke, transient ischemic attack, or intracerebral hemorrhage in an administrative claims database.

BACKGROUND Stroke patients have a high risk for recurrence, which is positively correlated with the number of risk factors. The assessment of risk factors is essential in both stroke outcomes research and the surveillance of stroke burden. However, methods for assessment of risk factors using claims data are not well developed. METHODS We enrolled 6469 patients with acute ischemic stroke, transient ischemic attack, or intracerebral hemorrhage from hospital-based stroke registries, which were linked with Taiwans National Health Insurance (NHI) claims database. We developed algorithms using diagnosis codes and prescription data to identify stroke risk factors including hypertension, diabetes, hyperlipidemia, atrial fibrillation (AF), and coronary artery disease (CAD) in the claims database using registry data as reference standard. We estimated the kappa statistics to quantify the agreement of information on the risk factors between claims and registry data. RESULTS The prevalence of risk factors in the registries was hypertension 77.0%, diabetes 39.1%, hyperlipidemia 55.6%, AF 10.1%, and CAD 10.9%. The highest kappa statistics were 0.552 (95% confidence interval 0.528-0.577) for hypertension, 0.861 (0.836-0.885) for diabetes, 0.572 (0.549-0.596) for hyperlipidemia, 0.687 (0.663-0.712) for AF, and 0.480 (0.455-0.504) for CAD. Algorithms based on diagnosis codes alone could achieve moderate to high agreement in identifying the selected risk factors, whereas prescription data helped improve identification of hyperlipidemia. CONCLUSIONS We tested various claims-based algorithms to ascertain important risk factors in stroke patients. These validated algorithms are useful for assessing stroke risk factors in future studies using Taiwans NHI claims data.

DIAGNOSIS AND FOLLOW-UP OF CAROTID-CAVERNOUS FISTULAS BY CAROTID DUPLEX SONOGRAPHY AND TRANSCRANIAL COLOR DOPPLER IMAGING

To investigate the suitability of extracranial carotid duplex (ECD) and transcranial color Doppler imaging (TCDI) in the diagnosis and follow-up of treatment in patients with carotid-cavernous fistulas (CCF), combined ECD and TCDI examinations were studied in seven patients with traumatic CCF. According to angiography, four patients had direct CCF, two indirect CCF and one both direct and indirect CCF. In ECD, hemodynamic parameters of the feeding artery showed an abnormally increased flow volume and decreased resistivity indices in five direct CCFs from the internal carotid artery and one indirect CCF from the external carotid artery. Direct visualization of the CCF was achieved in patients with direct CCF only, and revealed itself as a heterogeneous mosaic flash resulting from high flow velocities and turbulence. Patterns of venous drainage were detected via the transorbital and transforaminal windows in seven and five patients (four direct and one indirect CCF patients), respectively. These abnormal findings were improved or even normalized after successful treatment. In conclusion, combined ECD and TCDI examinations appear to be useful for the diagnosis and follow-up of CCF.

Validation of a novel claims-based stroke severity index in patients with intracerebral hemorrhage

Background Stroke severity is an important outcome predictor for intracerebral hemorrhage (ICH) but is typically unavailable in administrative claims data. We validated a claims-based stroke severity index (SSI) in patients with ICH in Taiwan. Methods Consecutive ICH patients from hospital-based stroke registries were linked with a nationwide claims database. Stroke severity, assessed using the National Institutes of Health Stroke Scale (NIHSS), and functional outcomes, assessed using the modified Rankin Scale (mRS), were obtained from the registries. The SSI was calculated based on billing codes in each patients claims. We assessed two types of criterion-related validity (concurrent validity and predictive validity) by correlating the SSI with the NIHSS and the mRS. Logistic regression models with or without stroke severity as a continuous covariate were fitted to predict mortality at 3, 6, and 12 months. Results The concurrent validity of the SSI was established by its significant correlation with the admission NIHSS (r = 0.731; 95% confidence interval [CI], 0.705–0.755), and the predictive validity was verified by its significant correlations with the 3-month (r = 0.696; 95% CI, 0.665–0.724), 6-month (r = 0.685; 95% CI, 0.653–0.715) and 1-year (r = 0.664; 95% CI, 0.622–0.702) mRS. Mortality models with NIHSS had the highest area under the receiver operating characteristic curve, followed by models with SSI and models without any marker of stroke severity. Conclusions The SSI appears to be a valid proxy for the NIHSS and an effective adjustment for stroke severity in studies of ICH outcome with administrative claims data.

Predicting symptomatic intracerebral hemorrhage after intravenous thrombolysis: stroke territory as a potential pitfall.

BACKGROUND Stroke vascular territories may influence response to thrombolysis, although supporting data are limited. The aim of the study was to test the hypothesis that the current available prediction scores might inaccurately estimate the risk of symptomatic intracerebral hemorrhage (SICH) after intravenous thrombolysis in patients with posterior circulation stroke. METHODS We applied the Safe Implementation of Thrombolysis in Stroke (SITS) SICH risk score to data from four hospital-based stroke registries. Patients were grouped according to anterior or posterior circulation stroke. The main outcome measure was SICH per various definitions. Performance of the risk score was assessed with the c statistic. RESULTS Data of 518 thrombolyzed patients (434 anterior, 84 posterior) were studied. The overall rate of SICH varied from 3.5% to 6.9% depending on the SICH definition. Patients with posterior circulation stroke were less likely to have post-thrombolysis SICH per NINDS (P=0.042), per ECASS II (P=0.013), or any ICH (P=0.001), and their rate of SICH was markedly lower than predicted (1.2% versus 7.1% by the NINDS definition; 0% versus 4.8%, ECASS II; 0% versus 1.6%, SITS-MOST). The SITS SICH risk score shows moderate model discrimination across the SICH definitions, with c statistic ranging from 0.64 to 0.70. CONCLUSIONS The risk of SICH after intravenous thrombolysis in patients with posterior circulation stroke was low enough to render the SITS SICH risk score or other similar prediction models unnecessary. Awareness of stroke territory might help clinicians judiciously use the risk assessment models.

Automated Segmentation and Quantification of White Matter Hyperintensities in Acute Ischemic Stroke Patients with Cerebral Infarction

White matter hyperintensities (WMHs) of presumed vascular origin are common in ageing population, especially in patients with acute cerebral infarction and the volume has been reported to be associated with mental impairment and the risk of hemorrhage from antithrombotic agents. WMHs delineation can be computerized to minimize human bias. However, the presence of cerebral infarcts greatly degrades the accuracy of WMHs detection and thus limits the application of computerized delineation to patients with acute cerebral infarction. We propose a computer-assisted segmentation method to depict WMHs in the presence of cerebral infarcts in combined T1-weighted, fluid attenuation inversion recovery, and diffusion-weighted magnetic resonance imaging (MRI). The proposed method detects WMHs by empirical threshold and atlas information, with subtraction of white matter voxels affected by acute infarction. The method was derived using MRI from 25 hemispheres with WMHs only and 13 hemispheres with both WMHs and cerebral infarcts. Similarity index (SI) and correlation were utilized to assess the agreement between the new automated method and a gold standard visually guided semi-automated method done by an expert rater. The proposed WMHs segmentation approach produced average SI, sensitivity and specificity of 83.142±11.742, 84.154±16.086 and 99.988±0.029% with WMHs only and of 68.826±14.036, 74.381±18.473 and 99.956±0.054% with both WMHs and cerebral infarcts in the derivation cohort. The performance of the proposed method with an external validation cohort was also highly consistent with that of the experienced rater.

Oxfordshire community stroke project classification improves prediction of post-thrombolysis symptomatic intracerebral hemorrhage

BackgroundThe Oxfordshire Community Stroke Project (OCSP) classification is a simple stroke classification system with value in predicting clinical outcomes. We investigated whether and how the addition of OCSP classification to the Safe Implementation of Thrombolysis in Stroke (SITS) symptomatic intracerebral hemorrhage (SICH) risk score improved the predictive performance.MethodsWe constructed an extended risk score by adding an OCSP component, which assigns 3 points for total anterior circulation infarcts, 0 point for partial anterior circulation infarcts or lacunar infarcts. Patients with posterior circulation infarcts were assigned an extended risk score of zero. We analyzed prospectively collected data from 4 hospitals to compare the predictive performance between the original and the extended scores, using area under the receiver operating characteristic curve (AUC) and net reclassification improvement (NRI).ResultsIn a total of 548 patients, the rates of SICH were 7.3% per the National Institute of Neurological Diseases and Stroke (NINDS) definition, 5.3% per the European-Australasian Cooperative Acute Stroke Study (ECASS) II, and 3.5% per the SITS-Monitoring Study (SITS-MOST). Both scores effectively predicted SICH across all three definitions. The extended score had a higher AUC for SICH per NINDS (0.704 versus 0.624, P = 0.015) and per ECASS II (0.703 versus 0.612, P = 0.016) compared with the SITS SICH risk score. NRI for the extended risk score was 22.3% (P = 0.011) for SICH per NINDS, 21.2% (P = 0.018) per ECASS II, and 24.5% (P = 0.024) per SITS-MOST.ConclusionsIncorporation of the OCSP classification into the SITS SICH risk score improves risk prediction for post-thrombolysis SICH.

Low cholesterol level associated with severity and outcome of spontaneous intracerebral hemorrhage: Results from Taiwan Stroke Registry

The relationship between cholesterol level and hemorrhagic stroke is inconclusive. We hypothesized that low cholesterol levels may have association with intracerebral hemorrhage (ICH) severity at admission and 3-month outcomes. This study used data obtained from a multi-center stroke registry program in Taiwan. We categorized acute spontaneous ICH patients, based on their baseline levels of total cholesterol (TC) measured at admission, into 3 groups with <160, 160–200 and >200 mg/dL of TC. We evaluated risk of having initial stroke severity, with National Institutes of Health Stroke Scale (NIHSS) >15 and unfavorable outcomes (modified Rankin Scale [mRS] score >2, 3-month mortality) after ICH by the TC group. A total of 2444 ICH patients (mean age 62.5±14.2 years; 64.2% men) were included in this study and 854 (34.9%) of them had baseline TC <160 mg/dL. Patients with TC <160 mg/dL presented more often severe neurological deficit (NIHSS >15), with an adjusted odds ratio [aOR] of 1.80; 95% confidence interval [CI], 1.41–2.30), and 3-month mRS >2 (aOR, 1.41; 95% CI, 1.11–1.78) using patients with TC >200 mg/dL as reference. Those with TC >160 mg/dL and body mass index (BMI) <22 kg/m2 had higher risk of 3-month mortality (aOR 3.94, 95% CI 1.76–8.80). Prior use of lipid-lowering drugs (2.8% of the ICH population) was not associated with initial severity and 3-month outcomes. A total cholesterol level lower than 160 mg/dL was common in patients with acute ICH and was associated with greater neurological severity on presentation and poor 3-month outcomes, especially with lower BMI.