Influence of differences in case mix on the better outcome of smokers after intravenous thrombolysis for acute cerebral ischemia

Influence Factors and Predictive Models for the Outcome of Patients with Ischemic Stroke after Intravenous Thrombolysis: A Multicenter Retrospective Cohort Study

Objective

Intravenous thrombolysis (IVT) is currently the main effective treatment for patients with ischemic stroke. This study aimed to analyze the factors affecting the early neurological recovery and prognosis of thrombolytic therapy after surgery and to construct predictive models.

Materials and Methods

A total of 849 patients with ischemic stroke who received IVT treatment at six centers from June 2017 to March 2021 were included. Patients were divided into the training cohort and the validation cohort. Based on the independent factors that influence the early recovery of neurological function and the prognosis, the respective predictive nomograms were established. The predictive accuracy and discrimination ability of the nomograms were evaluated by ROC and calibration curve, while the decision curve and clinical impact curve were adopted to evaluate the clinical applicability of the nomograms.

Results

The nomogram constructed based on the factors affecting the prognosis in 3 months had ideal accuracy as the AUC (95% CI) was 0.901 (0.874~0.927) in the training cohort and 0.877 (0.826~0.929) in the validation cohort. The accuracy of the nomogram is required to be improved, since the AUC (95% CI) of the training cohort and the validation cohort was 0.641 (0.597~0.685) and 0.627 (0.559~0.696), respectively.

Conclusions

Based on this ideal and practical prediction model, we can early identify and actively intervene in patients with ischemic stroke after IVT to improve their prognosis. Nevertheless, the accuracy of predicting nomograms for the recovery of early neurological function after IVT still needs improvement.

Effects of smoking on the prognosis of anterior circulation acute ischemic stroke with intravenous thrombolysis

OBJECTIVE

This is a single-center retrospective analysis of the clinical data of 516 patients with acute ischemic stroke who underwent intravenous thrombolysis. This study was conducted to compare the therapeutic efficacy of smokers and non-smokers.

METHODS

Univariate analysis was used to analyze and compare the clinical data of smokers and non-smokers. Multivariate analysis was used to assess risk factors affecting the 90-day modified Rankin Scale (mRS) score.

RESULTS

Among the 516 patients, 235 (45.5 %) were smokers. Univariate analysis showed that smokers have a better 90-day prognosis and a lower 90-day mRS score than non-smokers. Multivariate logistic regression analysis showed that smoking is not a protective factor affecting prognosis, while baseline National Institutes of Health Stroke Scale (NIHSS) score was an independent risk factor affecting the 90-day functional outcome. Subgroup analysis did not determine a relationship between the 90-day mRS score and the smoking intensity and duration.

CONCLUSION

Smoking was not associated with a good 90-day prognosis after intravenous thrombolysis (IVT) treatment. The good clinical outcome of smokers in univariate analysis was bound up with their baseline characteristics. Baseline NIHSS score was the independent risk factor that affected the 90-day outcome of AIS patients undergoing IVT.

Impact of Stroke Severity on the Smoking Paradox in Patients Treated with Intravenous Thrombolysis

OBJECTIVE

To our knowledge, no previous studies have investigated the impact of stroke severity on the smoking paradox after intravenous thrombolysis (IVT). We aimed to explore the contribution of stroke severity to the association between smoking and stroke prognosis after IVT.

METHODS

We enrolled consecutive patients who received IVT within 4.5 hours from stroke onset. A logistic regression model was used to estimate the unadjusted and adjusted odds ratios (ORs) with their 95% confidence intervals (CIs) for poor functional outcome and mortality at 3 months.

RESULTS

Among patients with moderate stroke, smokers experienced a lower risk of 3-month poor outcomes than non-smokers (33.0% vs. 44.4%, unadjusted OR: 0.616; 95% CI: 0.402-0.945). However, among those with severe stroke, smokers had a higher risk of 3-month poor outcomes than non-smokers (81.6% vs. 55.9%, unadjusted OR: 3.496; 95% CI: 1.207-10.127). After adjustment, the negative correlation between smoking and 3-month poor outcome following IVT lost statistical significance in patients with moderate stroke (OR: 0.677 [95% CI: 0.418-1.097]). However, smoking remained a risk factor for 3-month poor outcomes in patients with severe stroke (OR: 4.216 [95% CI: 1.236-14.385]). We also observed a significant interaction between smoking and stroke severity with regard to the risk of poor functional outcomes (p=0.023). However, no such interaction influenced mortality (p=0.901).

CONCLUSION

Stroke severity affects the association between smoking and 3-month clinical functional outcomes following IVT.

The association between smoking and unfavorable outcomes in acute ischemic stroke patients with mechanical thrombectomy

INTRODUCTION

Little is known about the relationship between smoking and clinical outcomes in acute ischemic stroke (AIS) patients undergoing mechanical thrombectomy (MT). The outcomes could depend on different stroke subtypes. The aim of this study was to investigate whether smoking affected differently the outcomes in patients with different stroke subtypes who received MT.

METHODS

AIS patients who underwent MT were prospectively enrolled from three hospitals between January 2014 and December 2018. Smokers were defined as current users of cigarettes. The stroke subtypes were classified according to TOAST criteria. Outcome measurements included treatment effects, intracerebral hemorrhage (ICH), and functional outcomes at 3 months. The effects of smoking on outcomes were assessed by logistic regression analysis.

RESULTS

A total of 128 AIS patients with MT were enrolled, including 64 smokers and 64 non-smokers. Logistic regression analysis indicated that smoking was related to higher risk of In-hospital ICH (OR=4.31; 95% CI: 1.10–16.96; p=0.036) in patients with cardioembolism subtype. Furthermore, smoking was also associated with lower rates of mild stroke at discharge (OR=0.07; 95% CI: 0.02–0.31; p<0.001) and functional independence (OR=0.13; 95% CI: 0.03–0.56; p=0.006) in patients with cardioembolism subtype.

CONCLUSIONS

In AIS patients undergoing MT, smoking could be related to a higher risk of In-hospital ICH and lower rates of mild stroke at discharge and functional independence if their stroke subtype is cardioembolism.

Smoking Paradox in Stroke Survivors?: Uncovering the Truth by Interpreting 2 Sets of Data

Background and Purpose- The observation that smokers with stroke could have better outcome than nonsmokers led to the term "smoking paradox." The controversy of such a complex claim has not been fully settled, even though different case mix was noted. Analyses were conducted on 2 independent data sets to evaluate and determine whether such a paradox truly exists. Methods- Taiwan Stroke Registry with 88 925 stroke cases, and MJ cohort with 541 047 adults participating in a medical screening program with 1630 stroke deaths developed during 15 years of follow-up (1994-2008). Primary outcome for stroke registry was functional independence at 3 months by modified Rankin Scale score ≤2, for individuals classified by National Institutes of Health Stroke Scale score at admission. For MJ cohort, mortality risk by smoking status or by stroke history was assessed by hazard ratio. Results- A >11-year age difference in stroke incidence was found between smokers and nonsmokers, with a median age of 60.2 years for current smokers and 71.6 years for nonsmokers. For smokers, favorable outcome in mortality and in functional assessment in 3 months with modified Rankin Scale score ≤2 stratified by the National Institutes of Health Stroke Scale score was present but disappeared when age and sex were matched. Smokers without stroke history had a ≈2-fold increase in stroke deaths (2.05 for ischemic stroke and 1.53 for hemorrhagic stroke) but smokers with stroke history, 7.83-fold increase, overshadowing smoking risk. Quitting smoking at earlier age reversed or improved outcome. Conclusions- "The more you smoke, the earlier you stroke, and the longer sufferings you have to cope." Smokers had 2-fold mortality from stroke but endured stroke disability 11 years longer. Quitting early reduced or reversed the harms.

"Smoking paradox" is not true in patients with ischemic stroke: a systematic review and meta-analysis

Background

Ischemic stroke (IS) is a common cause of death from vascular diseases. Studies have found that smoking increases the risk of ischemic stroke, but the association of smoking with the outcome of IS remains unclear. This meta-analysis aims to investigate the effect of smoking on the prognosis of IS.

Methods

We searched four electronic databases including PubMed, EMBASE, Cochrane library and Web of science for papers, published before January 2019. In this meta-analysis, Review Manager 5.3 software was used to calculate for the pooled estimate effect, as well as the inverse-variance method for pooled mean difference (MD) and odds ratio (OR) of incidence in two groups of population.

Results

A total of 14,789 citations were identified during the literature search, 21 studies were included in the meta-analyses after screening. The full-adjusted OR of poor prognostic outcome in smoking and nonsmoking patients with stroke was pooled as 0.96 (95% CI 0.77–1.21), suggested that smoking or not has no impact on prognosis of IS. The pooled MD of onset age between smoking and nonsmoking IS patients was − 10.05 (− 12.91, − 7.19), indicated that smoking causes first onset of IS to occur 10 years earlier.

Conclusions

This meta-analysis showed that smoking was not a protective factor for poor prognosis of IS. Smoking patients with IS are 10 years younger than nonsmoking patients at time of the first onset of stroke.

Meta-analysis of the Smoker’s Paradox in Acute Ischemic Stroke Patients Receiving Intravenous Thrombolysis or Endovascular Treatment

Introduction

The existence of the smoker’s paradox is controversial and potential mechanisms have not been explained. We aimed to explore the association between cigarette smoking and functional outcome at 3 months in patients with acute ischemic stroke who were treated with intravenous thrombolysis (IVT) or endovascular treatment (EVT).

Methods

This meta-analysis was conducted in accordance with the PRISMA guidelines. Studies exploring the association between smoking and good functional outcome (modified Rankin Scale score ≤ 2) following IVT or EVT were searched via the databases of PubMed, Embase, and the Cochrane Library from inception to August 8, 2018. Information on the characteristics of included studies was independently extracted by two investigators. Data were pooled using a random-effects or fixed-effects meta-analysis according to the heterogeneity of included studies.

Results

Among 20 identified studies, 15 reported functional outcomes following IVT, and five reported functional outcomes following EVT. Unadjusted analyses showed that smoking increased the odds of good functional outcomes with a pooled odds ratio (OR) of 1.48 (95% confidence interval [CI]: 1.36–1.60) after IVT and 2.10 (95% CI: 1.47–3.20) after EVT. Of IVT studies, only eight reported outcomes adjusted for covariates and none of the EVT studies reported adjusted outcomes. After adjustment, the relation between smoking and good functional outcome following IVT lost statistical significance (OR 1.14 [95% CI: 0.81–1.59]).

Conclusion

Our meta-analysis suggested that smoking was not associated with good functional outcome (mRS ≤ 2) at 3 months in patients with acute ischemic stroke who were treated with intravenous thrombolysis.

Implications

The existence of the smoker’s paradox is controversial. A previous letter by Plas et al. published in 2013 reported a positive result for the association between smoking and good functional outcome at 3 months in acute ischemic stroke patients who received intravenous thrombolysis (IVT). However, a major limitation of their meta-analysis was that the process of data synthesis was based on unadjusted data. Therefore, we conducted this meta-analysis to investigate the association based on adjusted data and a larger sample size. Our meta-analysis suggested that smoking was not associated with good functional outcome after adjusting for covariates.

Impact of Smoking on Clinical Outcome and Recanalization After Intravenous Thrombolysis for Stroke

Background and Purpose—

The impact of smoking on prognosis after stroke is controversial. We aimed to assess the relationship between smoking status and stroke outcome after intravenous thrombolysis in a large cohort study by adjusting for potential confounders and incorporating recanalization rates.

Methods—

In a prospective observational multicenter study, we analyzed baseline and outcome data of consecutive patients with acute ischemic stroke treated with intravenous thrombolysis. Using uni- and multivariable modeling, we assessed whether smoking was associated with favorable outcome (modified Rankin Scale score of 0–1) and mortality. In addition, we also measured the occurrence of symptomatic intracranial hemorrhage and recanalization of middle cerebral artery. Patients reporting active cigarette use were classified as smokers.

Results—

Of 1865 patients, 19.8% were smokers (n=369). They were younger (mean 63.5 versus 71.3 years), less often women (56% versus 72.1%), and suffered less often from hypertension (61.3% versus 70.1%) and atrial fibrillation (22.7% versus 35.6%) when compared with nonsmokers. Favorable outcome and 3-month mortality were in favor of smokers in unadjusted analyses (45.8% versus 39.5% and 9.3% versus 15.8%, respectively), whereas symptomatic intracranial hemorrhage was comparable in both cohorts. Smoking was not associated with clinical outcome and mortality after adjusting for confounders (odds ratio, 1.20; 95% confidence interval, 0.91–1.61; P =0.197 and odds ratio, 1.08; 95% confidence interval, 0.68–1.71; P =0.755, respectively). However, smoking still independently predicted recanalization of middle cerebral artery in multivariable analyses (odds ratio, 2.68; 95% confidence interval, 1.11–6.43; P =0.028).

Conclusions—

Our study suggests that good outcome in smokers is mainly related to differences in baseline characteristics and not to biological effects of smoking. The higher recanalization rates in smokers, however, call for further studies.

Smoking-Thrombolysis Relationship Depends on Ischemic Stroke Subtype

BACKGROUND AND PURPOSE

The relationship between smoking and the outcome in patients received thrombolysis is undetermined. The outcome could be influenced by different stroke subtypes. This study aimed to explore whether smoking had any impact on the outcome in patients with stroke of different subtypes who received intravenous thrombolysis.

METHODS

All patients who received intravenous thrombolysis within 4.5 hours after symptom onset from the Thrombolysis Implementation and Monitor of Acute Ischemic Stroke in China (TIMS-China) database were eligible to be entered into this analysis. Smokers were considered if they smoked at least 1 cigarette/d for >6 months before stroke. Ischemic stroke subtype was classified by using the Trial of Org 10172 in Acute Stroke Treatment criteria. Outcome measurements included post-intravenous thrombolysis symptomatic intracranial hemorrhage within 7 days, mortality, and functional independence at 90 days. The relationship between smoking and thrombolysis was analyzed by using univariate and multivariate logistic regression models.

RESULTS

Of 1118 patients enrolled, we identified 454 smokers and 664 nonsmokers. After stratifying for ischemic stroke subtypes, multivariate analysis revealed a significant relationship between smoking and functional independence in patients with noncardioembolism stroke subtypes (large artery atherosclerosis: odds ratio [OR], 1.452; 95% confidence interval [CI], 1.053-2.264; small artery occlusion: OR, 4.275; 95% CI, 1.098-16.649; other: OR, 3.120; 95% CI, 1.162-8.373). Furthermore, smoking was specially related to lower rates of symptomatic intracranial hemorrhage (OR, 0.316; 95% CI, 0.120-0.832) and mortality (OR, 0.272; 95% CI, 0.128-0.577) in patients with large artery atherosclerosis subtype.

CONCLUSIONS

In patients treated with intravenous thrombolysis, smoking could be related to a better chance of functional independence if their subtype of stroke was noncardioembolic, and a lower risk of symptomatic intracranial hemorrhage and mortality in those with large artery atherosclerosis.

Smoking is Not a Good Prognostic Factor following First-Ever Acute Ischemic Stroke

Background and Purpose

There is evidence that smoking increases stroke risk; however, the effect of smoking on functional outcome after stroke is unclear. The aim of this study was to explore the effect of smoking status on outcome following acute ischemic stroke.

Methods

We assessed 1,117 patients with first-ever acute cerebral infarction and no prestroke disability whose functional outcome was measured after three months. A poor outcome was defined as a modified Rankin Scale score of ≥2. Smoking within one month prior to admission was defined as current smoking. Our analysis included demographics, vascular risk factors, initial National Institutes of Health Stroke Scale (NIHSS) score, stroke subtype, onset-to-admission time, thrombolytic therapy, initial blood pressure, and prognostic blood parameters as covariates.

Results

At baseline, current smokers were predominantly male, approximately 10 years younger than non-smokers (mean age, 58.6 vs. 68.3 years), and less likely to have hypertension and atrial fibrillation (53.9% vs. 65.4% and 8.7% vs. 25.9%, respectively), with a lower mean NIHSS score (4.6 vs. 5.7). The univariate analyses revealed that current smokers had a better functional outcome and significantly fewer deaths at three months follow-up when compared with non-smokers (functional outcome: 64.0% vs. 58.4%, P=0.082; deaths: 3.0% vs. 8.4%, P=0.001); however, these effects disappeared after adjusting for covariates (P=0.168 and P=0.627, respectively).

Conclusions

In this study, smoking was not associated with a good functional outcome, which does not support the paradoxical benefit of smoking on functional outcome following acute ischemic stroke.

The smoking paradox: impact of smoking on recanalization in the setting of intra-arterial thrombolysis

BACKGROUND

The smoking paradox refers to a better outcome in smokers eligible for thrombolytic treatment in myocardial infarction or ischemic stroke. Recent findings suggest that current smokers may present higher recanalization rates after intravenous (IV) thrombolysis with recombinant tissue plasminogen activator (rt-PA). We evaluated the impact of smoking in a consecutive series of patients treated with intra-arterial (IA) rt-PA.

METHODS

We analyzed data collected between April 2007 and December 2012 in our prospective registry. All acute ischemic stroke patients with an arterial occlusion treated by IA rt-PA (± IV, ± thrombectomy) were included. Arterial status was monitored with conventional angiography during the IA procedure. The primary study outcome was a complete recanalization achieved immediately after termination of IA rt-PA infusion. Secondary outcomes included complete recanalization after the end of the endovascular therapy (including complete recanalization achieved after adjunctive thrombectomy), favorable outcome (90-day modified Rankin Score ≤2), 90-day all-cause mortality, and any intracerebral hemorrhage.

RESULTS

Among the 227 included patients, 18.5% (n = 42) were current smokers and 16.7% (n = 38) former smokers. Compared with nonsmokers, current smokers were younger, more often men, had less frequently hypertension, and cardioembolic etiology, whereas former smokers were more often men and had more frequently hypercholesterolemia. The rate of complete recanalization was 30% (n = 68) after IA rt-PA infusion and 49% after adjunctive thrombectomy. A higher complete recanalization rate was found both in current smokers (45.2%) and former smokers (42.1%) compared to nonsmokers (22.5%). After adjustment for potential confounders, the adjusted odds ratio (OR) for complete recanalization associated with ever-smokers was 2.51 [95% confidence interval (CI) 1.26-4.99; p = 0.009]. A similar adjusted OR was found when the complete recanalization achieved after thrombectomy was included (OR 2.18, 95% CI 1.13-4.19; p = 0.019). However, smoking status was not independently associated with favorable outcome (adjusted OR 1.41, 95% CI 0.62-3.22 for former smokers, and adjusted OR 1.35, 95% CI 0.59-3.05 for current smokers), 90-day all-cause mortality (adjusted OR 0.68, 95% CI 0.25-1.81 for former smokers, and adjusted OR 1.55, 95% CI 0.54-4.48 for current smokers) or intracerebral hemorrhage (adjusted OR 0.72, 95% CI 0.29-1.76 for former smokers, and adjusted OR 0.80, 95% CI 0.32-1.96 for current smokers).

CONCLUSIONS

IA rt-PA administration was more effective to achieve complete arterial recanalization in current as well as former smokers. The characterization of the smoking paradox pathophysiology may lead to the identification of a patient-target population with a favorable response to rt-PA therapy. However, the smoking paradox should not be misinterpreted and not be used to promote smoking.