Elevated level of D-dimer increases the risk of stroke

Impact of remote ischemic postconditioning on acute ischemic stroke in China: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

Acute ischemic stroke (AIS) is a significant health burden in China, affecting a sizable portion of the population. Conventional pharmacological treatments frequently fall short of desirable outcomes. Therefore, exploring alternative therapies is crucial. Remote ischemic postconditioning (RIPostC) is a noninvasive and cost-effective adjunctive therapy. This study aimed to investigate the efficacy and safety of RIPostC as an adjunctive therapy for AIS to inform clinical practice.

METHODS

A comprehensive search was conducted across the PubMed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), WanFang, Weipu (VIP), and China Biology Medicine disc (CBM) databases up to October 2023. All included studies underwent bias risk assessment using the Cochrane risk-of-bias assessment tool. The primary outcome measure was the National Institute of Health Stroke Scale (NIHSS), with secondary outcomes including the Barthel index (BI), D-dimer, C-reactive protein (CRP), fibrinogen (FIB), brain-derived neurotrophic factor (BDNF), modified Rankin scale (mRS), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels. The data were analyzed using fixed-effects and random-effects models in Review Manager, with mean differences (MDs) and 95% confidence intervals (CIs) calculated for each outcome. The grading of recommendations, assessment, development, and evaluations (GRADE) approach was used to evaluate the level of evidence for each outcome measure.

RESULTS

This meta-analysis included 38 studies, encompassing 4334 patients. Compared with the control group, the RIPostC group had significantly lower NIHSS scores, serum CRP, D-dimer, IL-6, TNF-α, and FIB levels, and increased BDNF levels. Moreover, it improved the patient's BI and mRS scores. According to the GRADE approach, the quality of evidence for mRS was deemed "moderate," while the NIHSS, BI, and CRP were rated as "low" quality. IL-6, TNF-α, FIB, D-dimer, and BDNF received "very low" quality ratings.

CONCLUSION

The findings suggest that RIPostC activates endogenous protective mechanisms, providing benefits to patients with AIS.

Predictive value of admission D-dimer levels in patient with acute ischaemic stroke and COVID-19: a second-wave prospective cohort study

OBJECTIVES

This study aimed to evaluate the predictive value of admission D-dimer levels for in-hospital mortality in patients with COVID-19 and acute ischaemic stroke.

DESIGN

Cohort (prospective).

SETTING

Tertiary referral hospital in the capital city of Indonesia conducted from June to December 2021.

PARTICIPANTS

60 patients with acute ischaemic stroke and COVID-19 were included. Patients were classified into D-dimer groups (low and high) according to a 2 110 ng/mL cut-off value, determined via receiver operating characteristic analysis.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was in-hospital mortality, with admission D-dimer levels as the major predictor. Secondary outcomes included associations between other demographic and clinical variables and the admission D-dimer value. Kaplan-Meier method was used to carry out survival analysis, with univariable and multivariable Cox regression performed to assess the association of D-dimer levels and other confounding variables (including demographic, clinical and laboratory parameters) with in-hospital mortality.

RESULTS

The findings demonstrated an association between elevated admission D-dimer levels (≥2 110 ng/mL) and an increased likelihood of death during hospitalisation. The adjusted HR was 14.054 (95% CI 1.710 to 115.519; p=0.014), demonstrating an increase in mortality risk after accounting for confounders such as age and diabetes history. Other significant predictors of mortality included a history of diabetes and increased white blood cell count.

CONCLUSIONS

Admission D-dimer levels may be a useful predictive indicator for the likelihood of death during hospitalisation in individuals with COVID-19 and acute ischaemic stroke.

COVID-19 induced ischemic stroke and mechanisms of viral entry in brain and clot formation: a systematic review and current update

Background: Coronavirus disease 2019, caused by SARS-CoV-2 (SCV-2) was stated as a pandemic on March 11 2020 by World Health Organization (WHO), and since then, it has become a major health issue worldwide. It mainly attacks the respiratory system with various accompanying complications, including cardiac injury, renal failure, encephalitis and Stroke.Materials and Methods: The current systematic review has been compiled to summarize the available literature on SCV-2 induced ischemic Stroke and its subtypes. Further, the mechanisms by which the virus crosses the blood-brain barrier (BBB) to enter the brain have also been explored. The role of CRP and D-dimer as potent prognostic markers was also explored. The literature search was carried out comprehensively on Google scholar, PubMed, SCOP US, Embase and Cochrane databases by following guidelines.Results: All the studies were reviewed thoroughly by authors and disagreements were resolved by consensus and help of the senior authors. The most common subtype of the IS was found to be large artery atherosclerosis in SCV-2 induced IS. Hypertension emerged as the most significant risk factor. The mechanism resulting in elevated levels of CRP and D-dimer have also been discussed. However, there is a scarcity of definitive evidence on how SCV-2 enters the human brain. The available literature based on various studies demonstrated that SCV-2 enters through the nasopharyngeal tract via olfactory cells to olfactory neurons, astrocytes and via choroid plexus through endothelial cells. Further, disruption of gut-brain axis has been also discussed.Conclusion: Data available in the literature is not adequate to come to a conclusion. Therefore, there is a need to carry out further studies to delineate the possible association between SCV-2 induced IS.

Preprocedural D-Dimer Level as a Predictor of First-Pass Recanalization and Functional Outcome in Endovascular Treatment of Acute Ischemic Stroke

We aimed to evaluate the association between preprocedural D-dimer levels and endovascular and clinical outcomes. We retrospectively reviewed patients with acute intracranial large-vessel occlusion who underwent mechanical thrombectomy. Plasma D-dimer levels were measured immediately before the endovascular procedure. Endovascular outcomes included successful recanalization, first-pass recanalization (first-pass effect (FPE) and modified FPE (mFPE)), thrombus fragmentation, and the number of passes of the thrombectomy device. Clinical outcomes were assessed at 3 months using the modified Rankin Scale. A total of 215 patients were included. Preprocedural D-dimer levels were lower in patients with FPE (606.0 ng/mL [interquartile range, 268.0-1062.0]) than in those without (879.0 ng/mL [437.0-2748.0]; p = 0.002). Preprocedural D-dimer level was the only factor affecting FPE (odds ratio, 0.92 [95% confidence interval, 0.85-0.98] per 500 ng/mL; p = 0.022). D-dimer levels did not differ significantly based on successful recanalization and thrombus fragmentation. The number of passes of the thrombectomy device was higher (p = 0.002 for trend) and the puncture-to-recanalization time was longer (p = 0.044 for trend) as the D-dimer levels increased. Patients with favorable outcome had significantly lower D-dimer levels (495.0 ng/mL [290.0-856.0]) than those without (1189.0 ng/mL [526.0-3208.0]; p < 0.001). Preprocedural D-dimer level was an independent factor for favorable outcome (adjusted odds ratio, 0.88 [0.81-0.97] per 500 ng/mL; p = 0.008). In conclusion, higher preprocedural D-dimer levels were significantly associated with poor endovascular and unfavorable functional outcomes.

Comparison of circulating lipid profiles, D-dimer and fibrinogen levels between hypertensive patients with and without stroke

BACKGROUND

Stroke is one of the leading causes of global mortality and disability, particularly in hypertensive patients. This study aimed to compare lipid profile, fibrinogen, and D-dimer levels between hypertensive patient with and without stroke.

METHODS

This was a facility-based cross-sectional study conducted from November 2022 to January 2023 among 115 hypertensive patients (70 patients without stroke and 45 with stroke) who had follow-up at Yikatit 12 Hospital Medical College, Ethiopia. All data analyses were done using SPSS version 25.0 and comparisons of variables between groups were made using the Chi-square test, independent sample t-test, and Mann-Whitney U test. Multiple logistic regression analysis was done to identify predictors of stroke among hypertensive patients. A p-value <0.05 was assumed to be statistically significant for all statistical tests.

RESULTS

Significantly elevated levels of TC, LDL-C, D-DI, and fibrinogen were observed in the stroke group than in the non-stroke group (p-value<0.05). The mean values of TC, D-DI, and fibrinogen were significantly higher in patients with ischemic stroke compared to those with hemorrhagic stroke. Duration of hypertension (AOR: 1.21; CI: 1.10, 2.09), TC (AOR:1.07; CI: 1.01, 1.22), D-DI (AOR: 1.15; CI: 1.05, 1.69) and fibrinogen (AOR:1.19; CI: 1.10, 2.89) were identified to be independent predictors of stroke in hypertensive patients.

CONCLUSION

The circulating levels of TC, LDL-C, D-DI and fibrinogen in hypertensive patients with stroke were significantly higher than in those without stroke. But only TC, D-DI, and fibrinogen were found to be predictors of stroke in hypertensives. Considerably higher TC, D-DI, and fibrinogen levels were also seen in patients with ischemic stroke than in those with hemorrhagic stroke. This confirms the key roles of dyslipidemia (hypercholesterolemia) and aberrant hemostatic activation to stroke development, notably ischemic stroke.

Liver Enzymes and the Risk of Stroke among the General Japanese Population: A Prospective Cohort Study

INTRODUCTION

Stroke is a major cause of morbidity and mortality. Liver enzymes, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGT), are markers of liver diseases with potential cardiovascular implications. This study aimed to investigate the prospective association between liver enzymes and stroke risk.

METHODS

We analyzed data from 3,379 men and 4,007 women without cardiovascular disease and registered in the Suita Study, a Japanese population-based prospective cohort study. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) of stroke risk were estimated per quintiles of ALT, AST, and GGT in men and women.

RESULTS

Within a median follow-up period of 16.7 years, 438 incident stroke events were diagnosed. In men, compared to the second quintiles, the fifth (highest) quintiles of liver enzymes showed increased stroke risks: HRs (95% CIs) = 2.07 (1.35, 3.18) in ALT, 1.66 (1.10, 2.53) in AST, and 1.76 (1.11, 2.81) in GGT. The associations did not change with cerebral infarction risk: HRs (95% CIs) = 2.09 (1.24, 3.50) in ALT, 1.84 (1.11, 3.06) in AST, and 1.74 (1.00, 3.04) in GGT. The lowest ALT, AST, and GGT quintiles tended to show increased stroke and cerebral infarction risks, yet these associations were statistically insignificant. No such associations were shown in women.

CONCLUSION

Elevated ALT, AST, and GGT levels were associated with increased stroke and cerebral infarction risks among Japanese men.

An overview of the neurological aspects in COVID-19 infection

The Crown-shaped, severe acute respiratory syndrome-Coronavirus-2 (SARS-CoV-2) triggered the globally fatal illness of Coronavirus disease-2019 (COVID-19). This infection is known to be initially reported in bats and has been causing major respiratory challenges. The primary symptoms of COVID-19 include fever, fatigue and dry cough. As progressed the complications may lead to acute respiratory distress syndrome (ADRS), arrhythmia and shock. This review illustrates the neurological and neuropsychiatric impairments due to COVID-19 infection. The SARS-CoV-2 virus enters via the hematogenous or neural route, spreads to the Central Nervous System (CNS), causing a blood-brain barrier (BBB) dysfunction. Recent scientific articles have reported that SARS-CoV-2 causes several neurological issues such as encephalitis, seizures, acute stroke, delirium, meningoencephalitis and Guillain-Barré Syndrome (GBS). As a long-term effect of this disease certain neuropsychiatric conditions are witnessed such as depression and anxiety. Invasion into followed by degeneration takes place causing an uncontrolled immune response. Transcription factors like NF-κB (nuclear factor kappa light chain enhancer of activated B cells), which modulate genes responsible for inflammatory response gets over expressed. Nrf2 (nuclear factor erythroid 2- related factor 2) counterpoises the inflammation by antioxidant response towards COVID-19 infection. Like every other infection, the severity of this infection leads to deterioration of major organ systems and even leads to death. By the columns of this review, we elaborate on the neurological aspects of this life-threatening infection.

Biomarkers Predictive of Long-Term Outcome After Ischemic Stroke: A Meta-Analysis

BACKGROUND AND PURPOSE

The goal of this study was to systematically review the utility of serum biomarkers in the setting of ischemic stroke (IS) to predict long-term outcome.

METHODS

A systematic literature review was performed using the PubMed and MEDLINE databases for studies published between 1986-2018. All studies assessing long-term functional outcome (defined as 30 days or greater) following IS with respect to serum biomarkers were included. Data were extracted and pooled using a meta-analysis of odds ratios.

RESULTS

Of the total 2928 articles in the original literature search, 183 studies were ultimately selected. A total of 127 serum biomarkers were included. Biomarkers were grouped into several categories: inflammatory (32), peptide/enzymatic (30), oxidative/metabolic (28), hormone/steroid based (23), and hematologic/vascular (14). The most commonly studied biomarkers in each category were found to be CRP, S100β, albumin, copeptin, and D-dimer. With the exception of S100β, all were found to be statistically associated with >30-day outcome after ischemic stroke.

CONCLUSIONS

Serum-based biomarkers have the potential to predict functional outcome in IS patients. This meta-analysis has identified CRP, albumin, copeptin, and D-dimer to be significantly associated with long-term outcome after IS. These biomarkers have the potential to serve as a platform for prognosticating stroke outcomes after 30 days. These serum biomarkers, some of which are routinely ordered, can be combined with imaging biomarkers and used in artificial intelligence algorithms to provide refined predictive outcomes after injury. Ultimately these tools will assist physicians in providing guidance to families with regards to long-term independence of patients.

The Role of Biomarkers in Atherothrombotic Stroke-A Systematic Review

Stroke represents the primary debilitating disease in adults and is the second-highest cause of death worldwide. Atherosclerosis, the most prevalent etiology for vascular conditions, is a continuous process that gradually creates and develops endothelial lesions known as atherosclerotic plaques. These lesions lead to the appearance of atherothrombotic stroke. In the last decades, the role of biological biomarkers has emerged as either diagnostic, prognostic, or therapeutic targets. This article aims to create a list of potential biomarkers related to atherothrombotic stroke by reviewing the currently available literature. We identified 23 biomarkers and assessed their roles as risk factors, detection markers, prognostic predictors, and therapeutic targets. The central aspect of these biomarkers is related to risk stratification, especially for patients who have not yet suffered a stroke. Other valuable data are focused on the predictive capabilities for stroke patients regarding short-term and long-term prognosis, including their influence over the acute phase treatment, such as rt-PA thrombolysis. Although the role of biomarkers is anticipated to be of extreme value in the future, they cannot yet compete with traditional stroke neuroimaging markers but could be used as additional tools for etiological diagnosis.

Relationships Between D-Dimer Levels and Stroke Risk as Well as Adverse Clinical Outcomes After Acute Ischemic Stroke or Transient Ischemic Attack: A Systematic Review and Meta-Analysis

Objective: Abnormal elevation of D-dimer levels is an important indicator of disseminated intravascular clotting. Therefore, we hypothesized that high D-dimer levels were associated with the risk of stroke and adverse clinical outcomes of patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA).

Methods: The present meta-analysis aimed to systematically analyze the associations between D-dimer and the risk of stroke as well as the clinical outcomes of patients with post-stroke or TIA. Meanwhile, dose–response analyses were conducted when there were sufficient data available. Three electronic databases including Pubmed, the Embase database, and the Cochrane Library were searched by two investigators independently. All the pooled results were expressed as risk ratios (RRs).

Results: Finally, 22 prospective cohort studies were included into this meta-analysis. The results suggested that high D-dimer levels were associated with increased risks of total stroke (RR 1.4, 95%CI 1.20–1.63), hemorrhagic stroke (RR 1.25, 95%CI 0.69–2.25), and ischemic Stroke (RR 1.55, 95%CI 1.22–1.98), and the dose-dependent relationship was not found upon dose–response analyses. Besides, the high D-dimer levels on admission were correlated with increased risks of all-cause mortality [RR 1.77, 95% confidence interval (CI) 1.26–2.49], 5-day recurrence (RR 2.28, 95%CI 1.32–3.95), and poor functional outcomes (RR 2.01, 95%CI 1.71–2.36) in patients with AIS or TIA.

Conclusions: On the whole, high D-dimer levels may be associated with the risks of total stroke and ischemic stroke, but not with hemorrhagic stroke. However, dose–response analyses do not reveal distinct evidence for a dose-dependent association of D-dimer levels with the risk of stroke. Besides, high D-dimer levels on admission may predict adverse clinical outcomes, including all-cause mortality, 5-day recurrence, and 90-day poor functional outcomes, of patients with AIS or TIA. More studies are warranted to quantify the effect of D-dimer levels on the risk of stroke or TIA, so as to verify and substantiate this conclusion in the future.

Cerebrovascular comorbidity, high blood levels of C-reactive protein and D-dimer are associated with disease outcomes in COVID-19 patients

The emerging coronavirus disease (COVID-19) swept the world, affecting more than 200 countries and territories. As of August 22, 2020, the pandemic infected more than 23,329,752 including 807,054 patients who have died. Although the main clinical features of the pandemic disease are respiratory, cerebrovascular comorbidities emerged as one of the leading causes of death associated with COVID-19. Different case reports have indicated that C-reactive protein (CRP) and D-dimer (pro-inflammatory biomarkers) were elevated in COVID-19 patients, which can significantly increase the risk of ischemic stroke. Available data on cerebrovascular complications in COVID-19 patients were collected and a meta-analysis was designed and carried out to evaluate the risk of severity and mortality associated with high levels of CRP and D-dimer levels in COVID-19 patients. In addition, we aimed to describe the overall event rate of pre-existing cerebrovascular disease in COVID-19 patients. In our analysis, 5,614 cases have been studied, out of these patients 164 cases have developed cerebrovascular comorbities. Cerebrovascular comorbidity increased the risk of disease severity (odd ratio = 4.4; 95% CI: 1.48 to 12.84) and mortality (odd ratio = 7.0; 95% CI: 2.56 to 18.99). Statistical analyses showed that CRP and D-dimer serum levels were elevated by six-folds in the severe cases of COVID-19 patients. This significant increase in these two proteins levels can serve as a vital indicator for COVID-19 patients who are at increased risk of severe COVID-19 cerebrovascular complications, such as stroke.

Involvement of the nervous system in COVID-19: The bell should toll in the brain

The world is fuming at SARS-CoV-2 for being the culprit for causing the devastating COVID-19, claiming millions of lives across the globe in the form of respiratory disorders. But lesser known are its effects on the CNS that are slowly surfacing in the worldwide population. Our review illustrates findings that claim SARS-CoV-2's arrival onto the ACE2 receptors of neuronal and glial cells mainly via CSF, olfactory nerve, trigeminal nerve, neuronal dissemination, and hematogenous pathways. The role of SARS-CoV-2 structural proteins in its smooth viral infectivity of the host cannot be ignored, especially the spike proteins that mediate spike attachment and host membrane fusion. Worth mentioning the nucleocapsid, envelope, and membrane proteins make the proliferation of SARS-CoV-2 much simpler than expected in spreading infection. This has led to catastrophic conditions like seizures, Guillain-Barré syndrome, viral encephalitis, meningoencephalitis, acute cerebrovascular disease, and respiratory failures. Placing a magnifying lens on the lesser-explored CNS consequences of COVID-19, we attempt to shift the focus of our readers onto the new supporting threats to which further studies are needed.

Young cryptogenic ischemic stroke: A descriptive analysis of clinical and laboratory characteristics, outcomes and stroke recurrence

BACKGROUND AND PURPOSE

Ischemic strokes (IS) occur also in young adults and despite an extensive work-up the cause of IS remains very often cryptogenic. Thus, effectiveness of secondary prevention may be unclear. We aimed to analyze a relationship among vascular risk factors (VRF), clinical and laboratory parameters, outcomes and recurrent IS (RIS) in young cryptogenic IS (CIS) patients.

SUBJECTS AND METHODS

The study set consisted of young acute IS patients < 50 years enrolled in the prospective HISTORY (Heart and Ischemic STrOke Relationship studY) study registered on ClinicalTrials.gov (NCT01541163). All analyzed patients underwent transesophageal echocardiography, 24-h and 3-week ECG-Holter to assess cause of IS according to the ASCOD classification. Recurrent IS (RIS) was recorded during a follow-up (FUP).

RESULTS

Out of 294 young enrolled patients, 208 (70.7%, 113 males, mean age 41.6 ± 7.2 years) were identified as cryptogenic. Hyperlipidemia (43.3%), smoking (40.6%) and arterial hypertension (37.0%) were the most frequent VRF. RIS occurred in 7 (3.4%) patients during a mean time of FUP 19 ± 23 months. One-year risk of RIS was 3.4% (95%CI: 1.4-6.8%). Patients with RIS were older (47.4 vs. 41.1 years, p = 0.007) and more often obese (71.4 vs. 19.7%, p = 0.006), and did not differ in any of other analyzed parameters and VRF. Multivariate logistic regression analysis showed obesity (OR: 9.527; 95%CI: 1.777-51.1) and the previous use of antiplatelets (OR: 15.68; 95%CI: 2.430-101.2) as predictors of recurrent IS.

CONCLUSION

Despite a higher presence of VRF in young CIS patients, the risk of RIS was very low. Obesity and previous use of antiplatelet therapy were found the only predictors of RIS.

Neurological Manifestations of Severe SARS-CoV-2 Infection: Potential Mechanisms and Implications of Individualized Mechanical Ventilation Settings

In December 2019, an outbreak of illness caused by a novel coronavirus (2019-nCoV, subsequently renamed SARS-CoV-2) was reported in Wuhan, China. Coronavirus disease 2019 (COVID-19) quickly spread worldwide to become a pandemic. Typical manifestations of COVID-19 include fever, dry cough, fatigue, and respiratory distress. In addition, both the central and peripheral nervous system can be affected by SARS-CoV-2 infection. These neurological changes may be caused by viral neurotropism, by a hyperinflammatory and hypercoagulative state, or even by mechanical ventilation-associated impairment. Hypoxia, endothelial cell damage, and the different impacts of different ventilatory strategies may all lead to increased stress and strain, potentially exacerbating the inflammatory response and leading to a complex interaction between the lungs and the brain. To date, no studies have taken into consideration the possible secondary effect of mechanical ventilation on brain recovery and outcomes. The aim of our review is to provide an updated overview of the potential pathogenic mechanisms of neurological manifestations in COVID-19, discuss the physiological issues related to brain-lung interactions, and propose strategies for optimization of respiratory support in critically ill patients with SARS-CoV-2 pneumonia.

Elevated plasma D-dimer levels are associated with short-term poor outcome in patients with acute ischemic stroke: a prospective, observational study

BACKGROUND

Elevated levels of plasma D-dimer increase the risk of ischemic stroke, stroke severity, and the progression of stroke status, but the association between plasma D-dimer level and functional outcome is unclear. The aim of this study is to investigate whether plasma D-dimer level is a determinant of short-term poor functional outcome in patients with acute ischemic stroke (AIS).

METHODS

This prospective study included 877 Chinese patients with AIS admitted to Renmin Hospital of Wuhan University within 72 h of symptom onset. Patients were categorized by plasma D-dimer level: Quartile 1(≤0.24 mg/L), Quartile 2 (0.25-0.56 mg/L), Quartile 3 (0.57-1.78 mg/L), and Quartile 4 (> 1.78 mg/L). The medical record of each patient was reviewed, and demographic, clinical, laboratory and neuroimaging information was abstracted. Functional outcome at 90 days was assessed with the modified Rankin Scale.

RESULTS

Poor outcome was present in 302 (34.4%) of the 877 patients that were included in the study (mean age, 64 years; male, 68.5%). After adjustment for potential confounding variables, higher plasma D-dimer level on admission was associated with poor outcome (adjusted odds ratio 2.257, 95% confidence interval 1.349-3.777 for Q4:Q1; P trend = 0.004). According to receiver operating characteristic (ROC) analysis, the best discriminating factor for poor outcome was a plasma D-dimer level ≥ 0.315 mg/L (area under the ROC curve 0.657; sensitivity 83.8%; specificity 41.4%).

CONCLUSION

Elevated plasma D-dimer levels on admission are significantly associated with poor outcome after admission for AIS, suggesting the potential role of plasma D-dimer level as a predictive marker for short-term poor outcome in patients with AIS.

Plasma D-Dimer Concentrations and Risk of Intracerebral Hemorrhage: A Systematic Review and Meta-Analysis

Background: The aim of our meta-analysis was to evaluate the association between plasma d-dimer and intracerebral hemorrhage (ICH).

Methods: Embase, Pubmed, and Web of Science were searched up to the date of March 19th, 2018, and manual searching was used to extract additional articles. Standard mean difference (SMD) with 95% confidence intervals (CI) was calculated to evaluate d-dimer levels.

Results: Thirteen studies including 891 ICH patients and 1,573 healthy controls were included. Our results revealed that higher levels of d-dimer were displayed in ICH patients than those in healthy controls (95% CI= 0.98–2.00, p< 0.001). Subgroup analysis based on continent of Asia and Europe, sample size, as well as age in relation to d-dimer levels between ICH patients and healthy controls did not change the initial observation; whereas no differences of d-dimer levels were found between ICH and controls in America.

Conclusions: This meta-analysis revealed that high level of d-dimer is associated with the risk of ICH. Plasma d-dimer is suggested to be a potential biomarker for patients with ICH in Asia and Europe rather than in America. There were no impact of sample size-related differences and age-related diversities on the risk of ICH with respect to d-dimer levels.