Abstract 19: Using the Heckman Selection Model to Assess Selection Bias in Ischemic Stroke Patients with Documented NIHSS

2015 ◽  
Vol 8 (suppl_2) ◽  
Author(s):  
Michael P Thompson ◽  
Zhehui Luo ◽  
Joseph Gardiner ◽  
James F Burke ◽  
Mathew J Reeves
Keyword(s):  
Ischemic Stroke ◽  
Correlation Coefficient ◽  
Selection Bias ◽  
Large Scale ◽  
Selection Process ◽  
Selection Model ◽  
Stroke Patients ◽  
Heckman Selection Model ◽  
Nihss Score ◽  
Heckman Selection

Objective: Complete documentation in large scale datasets such as administrative data or disease registries is often difficult. Given that the subset of patients with complete data documentation are most likely not a random sample of patients, selection bias threatens the validity of results if a complete case analysis is used. To demonstrate, we will assess the presence and magnitude of selection bias in ischemic stroke patients with documented National Institute of Health Stroke Scale (NIHSS) [[Unable to Display Character: &#8211;]] which is often incomplete [[Unable to Display Character: &#8211;]] using the Heckman Selection Model. Methods: Patient level variables including demographics, comorbidities, clinical EMS and admission variables, and medical history/comorbidities were obtained from 10,717 ischemic stroke patients aged 65 and older in the Michigan Stroke Registry in 2009-2012. The Heckman Selection Model assesses the presence and magnitude of selection bias by estimating a correlation coefficient between error components of a linear regression model predicting patient NIHSS score [[Unable to Display Character: &#8211;]] the outcome model [[Unable to Display Character: &#8211;]] and a binary probit model predicting NIHSS documentation [[Unable to Display Character: &#8211;]] the selection model [[Unable to Display Character: &#8211;]] conditional on patient and hospital predictors. The outcome model predicting NIHSS score was specified using a backward selection process with stepwise deletion of non-significant predictors. The selection model included all variables in the outcome model, plus additional significant predictors of NIHHS documentation. Quasi-maximum likelihood estimation was used to produce robust standard errors. All analyses were done using PROC QLIM procedure in SAS. Results: 7,956 cases (74.2%) of cases had NIHSS documented. Significant predictors in the outcome and selection models are shown in the Table. The Heckman Selection Model found a statistically significant but modest correlation coefficient of ρ =0.1089 (SE=0.0119, p<0.0001). The positive correlation indicates that NIHSS was more likely to be documented in patients with higher NIHSS scores, i.e., more severe strokes. Conclusions: We found statistically significant albeit weak selection bias in the documentation of NIHSS in stroke patients. The Heckman Selection Model is a novel method that can be used to assess the presence and magnitude of selection bias when missing data is common.

Is Openness Penalized? Stock Returns around Earnings Warnings

2007 ◽  
Vol 82 (4) ◽  
pp. 1055-1087 ◽  
Author(s):  
Jennifer W. Tucker
Keyword(s):  
Stock Returns ◽  
Selection Bias ◽  
Selection Model ◽  
Bad News ◽  
Short Term ◽  
Heckman Selection Model ◽  
Earnings Announcement ◽  
Self Selection ◽  
Earnings Warnings ◽  
Heckman Selection

Prior research finds that firms warning investors of an earnings shortfall experience lower returns than non-warning firms with similar risks and earnings news. Openness thus appears to be penalized by investors. Yet, this finding may be due to a self-selection bias that occurs when firms with a larger amount of unfavorable non-earnings news (“other bad news”) are more likely to warn. In this paper I use a Heckman selection model to infer the amount of other bad news and document that, on average, warning firms have a larger amount of other bad news than non-warning firms. After controlling for this effect, I find that warning firms' returns remain lower than those of non-warning firms in a short-term window ending five days after earnings announcement. When this window is extended by three months, however, warning and non-warning firms exhibit similar returns. My evidence suggests that openness is ultimately not penalized by investors.

Pre-Admission CHADS2 and CHA2DS2-VASc Scores on Early Neurological Worsening

2021 ◽  
pp. 1-8
Author(s):  
Ki-Woong Nam ◽  
Chi Kyung Kim ◽  
Sungwook Yu ◽  
Jong-Won Chung ◽  
Oh Young Bang ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Stroke Risk ◽  
Multivariable Analysis ◽  
National Institutes Of Health ◽  
Risk Scores ◽  
Stroke Patients ◽  
Nihss Score ◽  
Early Neurological Deterioration ◽  
Close Relationship ◽  
The Relationship

<b><i>Background:</i></b> Stroke risk scores (CHADS<sub>2</sub> and CHA<sub>2</sub>DS<sub>2</sub>-VASc) not only predict the risk of stroke in atrial fibrillation (AF) patients, but have also been associated with prognosis after stroke. <b><i>Objective:</i></b> The aim of this study was to evaluate the relationship between stroke risk scores and early neurological deterioration (END) in ischemic stroke patients with AF. <b><i>Methods:</i></b> We included consecutive ischemic stroke patients with AF admitted between January 2013 and December 2015. CHADS<sub>2</sub> and CHA<sub>2</sub>DS<sub>2</sub>-VASc scores were calculated using the established scoring system. END was defined as an increase ≥2 on the total National Institutes of Health Stroke Scale (NIHSS) score or ≥1 on the motor NIHSS score within the first 72 h of admission. <b><i>Results:</i></b> A total of 2,099 ischemic stroke patients with AF were included. In multivariable analysis, CHA<sub>2</sub>DS<sub>2</sub>-VASc score (adjusted odds ratio [aOR] = 1.17, 95% confidence interval [CI] = 1.04–1.31) was significantly associated with END after adjusting for confounders. Initial NIHSS score, use of anticoagulants, and intracranial atherosclerosis (ICAS) were also found to be closely associated with END, independent of the CHA<sub>2</sub>DS<sub>2</sub>-VASc score. Multivariable analysis stratified by the presence of ICAS demonstrated that both CHA<sub>2</sub>DS<sub>2</sub>-VASc (aOR = 1.20, 95% CI = 1.04–1.38) and CHADS<sub>2</sub> scores (aOR = 1.24, 95% CI = 1.01–1.52) were closely related to END in only patients with ICAS. In patients without ICAS, neither of the risk scores were associated with END. <b><i>Conclusions:</i></b> High CHA<sub>2</sub>DS<sub>2</sub>-VASc score was associated with END in ischemic stroke patients with AF. This close relationship is more pronounced in patients with ICAS.

scholarly journals Comparison of Tryglicerides Levels and Total Cholesterol in Ischemic Stroke and Haemorrhagic Stroke Patients

2020 ◽  
Vol 1 (2) ◽  
pp. 49
Author(s):  
Hijriyah Putri Tarmizi Hasibuan ◽  
Isra Thristy
Keyword(s):  
Ischemic Stroke ◽  
Total Cholesterol ◽  
Large Scale ◽  
Hemorrhagic Stroke ◽  
Total Cholesterol Level ◽  
Haemorrhagic Stroke ◽  
Total Sample ◽  
Stroke Patients ◽  
Average Value ◽  
Significant Difference

Background: Stroke is the second largest cause of death in the world. Stroke is classified based on its etiology as ischemic stroke and hemorrhagic stroke. Most large-scale studies on the risk of total cholesterol and triglyceride levels in stroke are not distinguished between ischemic and hemorrhagic strokes. Purposes: The purpose of this study was to determine the comparison of triglyceride and total cholesterol levels in ischemic stroke patients with hemorrhagic stroke. Method: Descriptive analytic study using medical records of patients at Medan Haji General Hospital in 2018-2019. The number of ischemic stroke patients is 28 patients and hemorrhagic stroke 28 patients with a total sample of 56 patients. Results: In ischemic stroke patients, the average value of triglyceride levels was 144.75 mg/dL and the average value of total cholesterol was 250.93 mg/dL. In hemorrhagic stroke patients, the average value of triglyceride levels is 126.93 mg/dL and the average total cholesterol level is 174.25 mg/dL. Conclusion: From this study we found a significant difference in total cholesterol between ischemic and hemorrhagic strokes. No significant difference was found in triglycerides between ischemic and hemorrhagic strokes.

Abstract TP315: D-dimer is Associated With 30-day Mortality in Acute Ischemic Stroke With Active Cancer

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Ki Woong Nam ◽  
Chi Kyung Kim ◽  
Tae Jung Kim ◽  
Sang Joon An ◽  
Kyungmi Oh ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Infarct Volume ◽  
Hemorrhagic Transformation ◽  
Stroke Patients ◽  
Nihss Score ◽  
Patients With Cancer ◽  
Advanced Stages ◽  
D Dimer ◽  
Active Cancer

Background: Stroke in cancer patients is not rare, but is a devastating event with high mortality. However, the predictors of mortality in stroke patients with cancer have not been well addressed. D-dimer could be a useful predictor because it can reflect both thromboembolic events and advanced stages of cancer. In this study, we evaluate the possibility of D-dimer as a predictor of 30-day mortality in stroke patients with active cancer. Methods: We included 210 ischemic stroke patients with active cancer. The data of 30-day mortality were collected by reviewing medical records. We also collected follow-up D-dimer levels in 106 (50%) participants to evaluate the effects of treatment response on D-dimer levels. Results: Of the 210 participants, 30-day mortality occurred in 28 (13%) patients. Higher initial NIHSS score, D-dimer levels, CRP levels, frequent cryptogenic mechanism, systemic metastasis, multiple vascular territory lesion, hemorrhagic transformation, and larger infarct volume were related to 30-day mortality. In the multivariate analysis, D-dimer [adjusted OR (aOR) = 2.19; 95% CI, 1.46-3.28, P < 0.001] predicted 30-day mortality after adjusting for confounders. Initial NIHSS score (aOR = 1.07; 95% CI, 1.00-1.14, P = 0.043) and hemorrhagic transformation (aOR = 3.02; 95% CI, 1.10-8.29, P = 0.032) were also significant independently from D-dimer levels. In the analysis of D-dimer changes after treatment, the mortality group showed no significant decrease of D-dimer levels, despite treatment, while the survivor group showed opposite responses. Conclusions: D-dimer levels may predict 30-day mortality in acute ischemic stroke patients with active cancer.

Abstract TP13: Procedural Time (Groin Puncture to Recanalization) Significantly Predicts Outcomes in Endovascular Treatment: A Pooled Analysis of SWIFT, STAR and SWIFT PRIME Trials

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Ameer E Hassan ◽  
Jeffrey L Saver ◽  
Mayank Goyal ◽  
David S Liebeskind ◽  
Reza Jahan ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Endovascular Treatment ◽  
Acute Ischemic Stroke ◽  
Clinical Outcomes ◽  
Pooled Analysis ◽  
Favorable Outcome ◽  
Stroke Patients ◽  
Nihss Score ◽  
Post Procedure ◽  
Procedural Time

Background: Recent single center studies have suggested that “procedural time” independent of “time to procedure” can affect outcomes of acute ischemic stroke patients undergoing endovascular treatment (ET). We performed a pooled analysis from three ET trials to determine the effect of procedural time on angiographic and clinical outcomes. Objective: To determine the relationship between procedural time and clinical outcomes among acute ischemic stroke patients undergoing successful recanalization with ET. Methods: We analyzed data from SWIFT, STAR and SWIFT PRIME trials. Baseline demographic and clinical characteristics, NIHSS score on admission, intracranial hemorrhage rates and mRS at 3 months post procedure were analyzed. TICI scale was used to grade post procedure angiographic recanalization. Procedural time was defined by the time interval between groin puncture and recanalization. We estimated the procedural time after which favorable clinical outcome was unlikely even after recanalization (futile) after age and NIHSS score adjustment. Results: We analyzed 301 patients who underwent ET and had near complete or complete recanalization (TICI 2b or 3). The procedural time (±SD) was significantly shorter in patients who achieved a favorable outcome (mRS 0-2) compared with those who did not achieve favorable outcome (44±25 vs 51±33 minutes, p=0.04). Table 1. In the multivariate analysis (including all baseline characteristics with a p value <0.05 as independent variables), shorter procedural time was a significant predictor of lower odds of unfavorable outcome (OR 0.49, 95% CI 0.28, 0.85, p=0.012). The rates of favorable outcomes were significantly higher when the procedural time was <60 minutes compared with ≥60 minutes (62% vs 45%, p=0.020). Conclusion: Procedural time in patients undergoing mechanical thrombectomy for acute ischemic stroke is an important determinant of favorable outcomes in those with near complete or complete recanalization.

Primary acute stroke thrombectomy within 3 h for large artery occlusion (PAST3-LAO): a pilot study

2016 ◽  
Vol 9 (4) ◽  
pp. 352-356 ◽  
Author(s):  
Yahia Lodi ◽  
Varun Reddy ◽  
Gorge Petro ◽  
Ashok Devasenapathy ◽  
Anas Hourani ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Intravenous Thrombolysis ◽  
Recombinant Tissue Plasminogen Activator ◽  
Artery Occlusion ◽  
Large Artery ◽  
Modified Rankin Scale ◽  
Stroke Patients ◽  
Nihss Score ◽  
Tissue Plasminogen ◽  
Poor Outcomes

Background and purposeIn recent trials, acute ischemic stroke (AIS) from large artery occlusion (LAO) was resistant to intravenous thrombolysis and adjunctive stent retriever thrombectomy (SRT) was associated with better perfusion and outcomes. Despite benefit, 39–68% of patients had poor outcomes. Thrombectomy in AIS with LAO within 3 h is performed secondary to intravenous thrombolysis, which may be associated with delay. The purpose of our study is to evaluate the safety, feasibility, recanalization rate, and outcome of primary SRT within 3 h without intravenous thrombolysis in AIS from LAO.MethodsBased on an institutionally approved protocol, stroke patients with LAO within 3 h were offered primary SRT as an alternative to intravenous recombinant tissue plasminogen activator. Consecutive patients who underwent primary SRT for LAO within 3 h from 2012 to 2014 were enrolled. Outcomes were measured using the modified Rankin Scale (mRS).Results18 patients with LAO of mean age 62.83±15.32 years and median NIH Stroke Scale (NIHSS) score 16 (10–23) chose primary SRT after giving informed consent. Near complete (TICI 2b in 1 patient) or complete (TICI 3 in 17 patients) recanalization was observed in all patients. Time to recanalization from symptom onset and groin puncture was 188.5±82.7 and 64.61±40.14 min, respectively. NIHSS scores immediately after thrombectomy, at 24 h and 30 days were 4 (0–12), 1 (0–12), and 0 (0–4), respectively. Asymptomatic perfusion-related hemorrhage developed in four patients (22%). 90-day outcomes were mRS 0 in 50%, mRS 1 in 44.4%, and mRS 2 in 5.6%.ConclusionsOur study demonstrates that primary SRT in AIS from LAO is safe and feasible and is associated with complete recanalization and good outcome. Further study is required.

Prevention of Venous Thromboembolism after Acute Ischemic Stroke with Enoxaparin Versus Unfractionated Heparin and the Impact of Stroke Severity.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 713-713 ◽  
Author(s):  
David G. Sherman ◽  
Gregory W. Albers ◽  
Christopher Bladin ◽  
Min Chen ◽  
Cesare Fieschi ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Venous Thromboembolism ◽  
Acute Ischemic Stroke ◽  
Stroke Severity ◽  
Primary Efficacy ◽  
Primary Efficacy Endpoint ◽  
Stroke Patients ◽  
Nihss Score ◽  
Vte Prophylaxis ◽  
Clinically Significant

Abstract Background: Venous thromboembolism (VTE) prophylaxis with low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH) is recommended in acute ischemic stroke patients, but most studies comparing LMWH and UFH are limited in methodology or sample size. The PREVAIL study was designed to assess the superiority of enoxaparin over UFH for VTE prophylaxis in acute ischemic stroke patients and to evaluate efficacy and safety according to stroke severity. Methods: Patients with acute ischemic stroke, confirmed by CT scan, and unable to walk unassisted due to motor impairment of the leg were enrolled in this prospective, open-label, parallel group, multicenter study. Patients from 15 countries were randomized within 48 h of stroke symptoms to receive enoxaparin 40 mg SC qd or UFH 5000 IU SC q12h for 10±4 days. Patients were stratified by NIH Stroke Scale score (NIHSS; severe ≥14, less severe &lt;14). The primary efficacy endpoint was the composite of symptomatic or asymptomatic deep-vein thrombosis (DVT), symptomatic pulmonary embolism (PE), or fatal PE during treatment. DVT was confirmed primarily by venography, or ultrasonography when venography was not practical. PE was confirmed by VQ or CT scan, or angiography. Primary safety endpoints included clinically significant intracranial and major extracranial bleeding. Results: 1762 acute ischemic stroke patients were randomized. Characteristics were similar between groups; mean age was 66.0±12.9 yrs, mean NIHSS score was 11.3. In the efficacy population, enoxaparin (n=666) and UFH (n=669) were given for a mean of 10.5±3.2 days. Enoxaparin resulted in a 43% relative reduction in the risk of the primary efficacy endpoint compared with UFH (10.2% vs 18.1%; RR 0.57; 95% CI 0.44–0.76; p=0.0001, adjusted for NIHSS score). Incidences of VTE events are shown in Table 1. Reductions in the primary endpoint remained significant in patients with a NIHSS score ≥14 (16.3% vs 29.7%, p=0.0036) and &lt;14 (8.3% vs 14.0%, p=0.0043). The composite of clinically significant intracranial and major extracranial bleeding was low and not significantly different between groups (Table 1). Conclusion: Enoxaparin 40 mg qd is superior to UFH q12h for reducing the risk of VTE in acute ischemic stroke patients, with no significant difference in clinically relevant bleeding. The reduction in VTE risk was consistent in patients with a NIHSS score ≥14 or &lt;14. Table 1: Incidence of VTE and bleeding Endpoint Enoxaparin n/N (%, 95% CI) UFH n/N (%, 95% CI) *P&lt;0.001 Symptomatic VTE 2/666 (0.3, 0.0–0.7) 6/669 (0.9, 0.2–1.6) Proximal DVT 30/666 (4.5, 2.9–6.1) 64/669 (9.6, 7.3–11.8)* Distal DVT 44/666 (6.6, 4.7–8.5) 85/669 (12.7, 10.2–15.2)* PE 1/666 (0.2, 0.0–0.4) 6/669 (0.9, 0.2–1.6) Composite of major extracranial and clinically significant intracranial bleeding 11/877 (1.3, 0.5–1.9) 6/872 (0.7, 0.1–1.2)

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