Thrombectomy improves functional independence in severe basilar artery occlusion with favorable collateral circulation.

BACKGROUND AND PURPOSE: This study aimed to investigate the effect of collateral circulation on the outcomes of thrombectomy versus medical management alone in basilar artery occlusion (BAO) patients with varying stroke severities. METHODS: Data from the ATTENTION cohort were used to perform a post-hoc analysis comparing the outcomes of thrombectomy with medical management in BAO patients with varying degrees of collateral circulation and stroke severity. Basilar Artery on Computed Tomography Angiography (BATMAN) scores were used to quantify the collateral circulation, and the effect was estimated through a primary outcome of 90-day functional independence (modified Rankin Scale score, mRS ≤2). Favorable versus unfavorable BATMAN scores were analyzed as both continuous and categorical variables, and an adjusted multivariate regression model was applied. RESULTS: Among 221 BAO patients, thrombectomy significantly improved functional independence compared to medical management in patients with favorable BATMAN scores (aOR 7.75, 95% CI 2.78-26.1), but not in those with unfavorable BATMAN scores (aOR 1.33, 95% CI 0.28-6.92; pinteraction = 0.028). When treated as a continuous variable, increased BATMAN score was found to be associated with a higher likelihood of functional independence in the thrombectomy group (aOR 1.97, 95% CI 1.44-2.81; pinteraction = 0.053). In severe stroke patients with higher BATMAN scores (National Institutes of Health Stroke Scale (NIHSS) ≥21), we identified a significant interaction for treatment effect with thrombectomy compared to medical management (pinteraction = 0.042). CONCLUSION: An increased BATMAN score was significantly associated with a higher probability of functional independence after thrombectomy than after medical management, particularly in patients with severe BAO.

The Change in Fibrinogen is Associated with Outcome in Patients with Acute Ischemic Stroke Treated with Endovascular Thrombectomy.

BACKGROUND: Fibrinogen has been identified as a modulator of the coagulation and inflammatory process. There is uncertainty about the relationship between the dynamic profile of fibrinogen levels and its impact on clinical outcomes in patients with acute ischemic stroke treated with endovascular thrombectomy. METHODS: We consecutively enrolled patients with acute ischemic stroke who underwent endovascular thrombectomy. Fibrinogen was measured on admission and during hospitalization. The change in fibrinogen (Δfibrinogen) was calculated as the highest follow-up fibrinogen minus admission fibrinogen, with a positive Δfibrinogen indicating an increase in fibrinogen level. Functional outcome was assessed by the modified Rankin Scale at 3 months. Poor outcome was defined as modified Rankin Scale > 2. RESULTS: A total of 346 patients were included (mean age 67.4 ± 13.6 years, 52.31% men). The median fibrinogen on admission was 2.77 g/L (interquartile range 2.30-3.39 g/L). The median Δfibrinogen was 1.38 g/L (interquartile range 0.27-2.79 g/L). Hyperfibrinogenemia (> 4.5 g/L) on admission was associated with an increased risk of poor outcome [odds ratio (OR) 5.93, 95% confidence interval (CI) 1.44-24.41, p = 0.014]. There was a possible U-shaped association of Δfibrinogen with outcomes, with an inflection point of - 0.43 g/L (p = 0.04). When Δfibrinogen was < - 0.43 g/L, a higher decrease in fibrinogen (lower Δfibrinogen value) was associated with a higher risk of poor outcome (OR 0.22, 95% CI 0.02-2.48, p = 0.219). When Δfibrinogen was > - 0.43 g/L, the risk of poor outcome increased with increasing fibrinogen (OR 1.27, 95% CI 1.04-1.54, p = 0.016). CONCLUSIONS: In patients with endovascular thrombectomy, hyperfibrinogenemia on admission was associated with poor functional outcomes at 3 months, whereas Δfibrinogen was associated with poor 3-month outcomes in a possible U-shaped manner.

Prognostic significance of uric acid change in acute ischemic stroke patients with reperfusion therapy.

BACKGROUND: Uric acid (UA) is an important endogenous free radical scavenger that has been found to have a neuroprotective effect. However, there is uncertainty about the relationship between UA change and outcome in acute ischemic stroke (AIS) patients with reperfusion therapy. METHODS: We consecutively enrolled AIS patients with reperfusion therapy. UA was measured upon admission and during hospitalization. The change in UA levels (ΔUA) was determined by calculating the difference between admission UA and the lowest UA among all follow-up measurements, with a positive ΔUA suggesting a decrease in UA levels. Functional outcome was assessed by modified Rankin Scale (mRS) at 3 months. Poor outcome was defined as mRS >2. RESULTS: A total of 361 patients were included (mean age 68.7 ± 13.9 years, 54.3% males). The mean UA on admission was 355 ± 96.1 µmol/L. The median ΔUA was 121 µmol/L (IQR 50-192 µmol/L) and 18 (5%) patients had increased UA levels. UA on admission was positively associated with good outcome (p for trend = 0.017). When patients were classified into quartiles by ΔUA, patients with the largest decrease in UA (Q4: 199-434 µmol/L) had a higher risk of poor outcome at 3 months compared to patients with the least decrease in UA (Q1: 0-57 µmol/L) (OR 2.55, 95% CI 1.09-5.98, p = 0.031). The risk of poor outcome increased with ΔUA (p for trend = 0.048). CONCLUSIONS: In patients with reperfusion therapy, high UA on admission was associated with a good 3-month outcome, while a greater decrease in UA was associated with poor outcome.

Association between low-density cholesterol change and outcomes in acute ischemic stroke patients who underwent reperfusion therapy.

BACKGROUND: Low-density lipoprotein cholesterol (LDL-C) can increase cardiovascular risk. However, the association between LDL-C change and functional outcomes in acute ischemic stroke (AIS) patients who underwent reperfusion therapy remains unclear. METHODS: Patients who received reperfusion therapy were consecutively enrolled. LDL-C measurement was conducted at the emergency department immediately after admission and during hospitalization. The change of LDL-C level (ΔLDL-C) was calculated by subtracting the lowest LDL-C among all measurements during hospitalization from the admission LDL-C. Poor functional outcome was defined as modified Rankin Scale (mRS) > 2 at 90 days. RESULTS: A total of 432 patients were enrolled (mean age 69.2 ± 13.5 years, 54.6 % males). The mean LDL-C level at admission was 2.55 ± 0.93 mmol/L. The median ΔLDL-C level was 0.43 mmol/L (IQR 0.08-0.94 mmol/L). A total of 263 (60.9 %) patients had poor functional outcomes at 90 days. There was no significant association between admission LDL-C level and functional outcome (OR 0.99, 95 % CI 0.77-1.27, p = 0.904). ΔLDL-C level was positively associated with poor functional outcome (OR 1.80, 95 % CI 1,12-2.91, p = 0.016). When patients were divided into tertiles according to ΔLDL-C, those in the upper tertile (T3, 0.80-3.98 mmol/L) were positively associated with poor functional outcomes compared to patients in the lower tertile (T1, -0.91-0.13 mmol/L) (OR 2.56, 95 % CI 1.22-5.36, p = 0.013). The risk of poor functional outcome increased significantly with ΔLDL-C tertile (P-trend = 0.010). CONCLUSIONS: In AIS patients who underwent reperfusion therapy, the decrease in LDL-C level during hospitalization was significantly associated with poor functional outcomes at 90 days.

Association between functional network connectivity, retina structure and microvasculature, and visual performance in patients after thalamic stroke: An exploratory multi-modality study.

BACKGROUND AND OBJECTIVE: Neuro-ophthalmologic symptoms and retinal changes have been increasingly observed following thalamic stroke, and there is mounting evidence indicating distinct alterations occurring in the vision-related functional network. However, the intrinsic correlations between these changes are not yet fully understood. Our objective was to explore the altered patterns of functional network connectivity and retina parameters, and their correlations with visual performance in patients with thalamic stroke. METHODS: We utilized resting-state functional MRI to obtain multi-modular functional connectivity (FC), and optical coherence tomography-angiography to measure various retina parameters, such as the retinal nerve fiber layer (RNFL), ganglion cell-inner plexiform layer (GCIPL), superficial vascular complex (SVC), and deep vascular complex. Visual acuity (VA) was used as a metric for visual performance. RESULTS: We included 46 patients with first-ever unilateral thalamic stroke (mean age 59.74 ± 10.02 years, 33 males). Significant associations were found between FC of attention-to-default mode and SVC, RNFL, and GCIPL, as well as between FC of attention-to-visual and RNFL (p < .05). Both RNFL and GCIPL exhibited significant associations with FC of visual-to-visual (p < .05). Only GCIPL showed an association with VA (p = .038). Stratified analysis based on a disease duration of 6 months revealed distinct and significant linking patterns in multi-modular FC and specific retina parameters, with varying correlations with VA in each subgroup. CONCLUSION: These findings provide valuable insight into the neural basis of the associations between brain network dysfunction and impaired visual performance in patients with thalamic stroke. Our novel findings have the potential to inform future targeted and individualized therapies. However, further comprehensive studies are necessary to validate our results.

The Association of Retinal Microvasculature With Gray Matter Changes and Structural Covariance Network: A Voxel-Based Morphometry Study.

Purpose: Increasing evidence suggests that retinal microvasculature may reflect global cerebral atrophy. However, little is known about the relation of retinal microvasculature with specific brain regions and brain networks. Therefore, we aimed to unravel the association of retinal microvasculature with gray matter changes and structural covariance network using a voxel-based morphometry (VBM) analysis. Methods: One hundred and forty-four volunteers without previously known neurological diseases were recruited from West China Hospital, Sichuan University between April 1, 2021, and December 31, 2021. Retinal microvasculature of superficial vascular plexus (SVP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP) were measured by optical coherence tomography angiography using an automatic segmentation. The VBM and structural covariance network analyses were applied to process brain magnetic resonance imaging (MRI) images. The associations of retinal microvasculature with voxel-wise gray matter volumes and structural covariance network were assessed by linear regression models. Results: In the study, 137 participants (mean age = 59.72 years, 37.2% men) were included for the final analysis. Reduced perfusion in SVP was significantly associated with reduced voxel-wise gray matter volumes of the brain regions including the insula, putamen, occipital, frontal, and temporal lobes, all of which were located in the anterior part of the brain supplied by internal carotid artery, except the occipital lobe. In addition, these regions were also involved in visual processing and cognitive impairment (such as left inferior occipital gyrus, left lingual gyrus, and right parahippocampal gyrus). In regard to the structural covariance, the perfusions in SVP were positively related to the structural covariance of the left lingual gyrus seed with the left middle occipital gyrus, the right middle occipital gyrus, and the left middle frontal gyrus. Conclusions: Poor perfusion in SVP was correlated with reduced voxel-wise gray matter volumes and structural covariance networks in regions related to visual processing and cognitive impairment. It suggests that retinal microvasculature may offer a window to identify aging related cerebral alterations.

Adenomyosis-Associated Ischemic Stroke: Pathophysiology, Detection and Management.

Female-specific risk factors for stroke have gradually received attention. The relationship between ischemic stroke and adenomyosis, a benign uterine disorder commonly present in parous women, is underrecognized. We aimed to provide an overview of the epidemiology, pathophysiological mechanisms, clinical characteristics, diagnostic considerations, and potential therapeutic strategies of adenomyosis-associated ischemic stroke. We shared our experience with the diagnosis and management of a patient, and summarized current findings and knowledge gaps of this disease based on previous literature. The relevant studies were searched in English and Chinese databases up to April 2022 using the keywords "ischemic stroke", "cerebral infarction" and "adenomyosis". Then, we provided a narrative review of the retrieved articles. Finally, the data of 32 cases were analyzed. We found that increased levels of carbohydrate antigen 125 and D-dimer and decreased level of hemoglobin are biomarkers of adenomyosis-associated ischemic stroke. In addition, hypercoagulability might be a key mechanism leading to thromboembolism in the cerebrovascular system. Additional studies are needed to find optimal prevention strategies for the disease. A better understanding of this "rare" pathogenesis of ischemic stroke may inform a more precise diagnosis and effective prevention strategy in middle-aged women with embolic stroke of undetermined source.

Characterization of Macular Structural and Microvascular Changes in Thalamic Infarction Patients: A Swept-Source Optical Coherence Tomography-Angiography Study.

Background: The retina and brain share similar neuronal and microvascular features. We aimed to investigate the retinal thickness and microvasculature in patients with thalamic infarcts compared with control participants. Material and methods: Swept-source optical coherence tomography (SS-OCT) was used to image the macular thickness (retinal nerve fiber layer, RNFL; ganglion cell-inner plexiform layer, GCIP), while OCT angiography was used to image the microvasculature (superficial vascular plexus, SVP; intermediate capillary plexus, ICP; deep capillary plexus, DCP). Inbuilt software was used to measure the macular thickness (µm) and microvascular density (%). Lesion volumes were quantitively assessed based on structural magnetic resonance images. Results: A total of 35 patients with unilateral thalamic infarction and 31 age−sex-matched controls were enrolled. Compared with control participants, thalamic infarction patients showed a significantly thinner thickness of RNFL (p < 0.01) and GCIP (p = 0.02), and a lower density of SVP (p = 0.001) and ICP (p = 0.022). In the group of patients, ipsilateral eyes showed significant reductions in SVP (p = 0.033), RNFL (p = 0.01) and GCIP (p = 0.043). When divided into three groups based on disease duration (<1 month, 1−6 months, and >6 months), no significant differences were found among these groups. After adjusting for confounders, SVP, ICP, DCP, RNFL, and GCIP were significantly correlated with lesion volume in patients. Conclusions: Thalamic infarction patients showed significant macular structure and microvasculature changes. Lesion size was significantly correlated with these alterations. These findings may be useful for further research into the clinical utility of retinal imaging in stroke patients, especially those with damage to the visual pathway.

Association Between Systemic Immune-Inflammation Index and Symptomatic Intracranial Hemorrhage in Acute Ischemic Stroke Patients Undergoing Endovascular Treatment.

BACKGROUND/OBJECTIVE: Systemic immune-inflammation index (SII) is a novel inflammatory factor, which may be involved in the destruction of the blood-brain barrier (BBB) after acute ischemic stroke (AIS); however, the association between SII and symptomatic intracranial hemorrhage (sICH) in AIS patients undergoing endovascular treatment (EVT) remains unclear. METHODS: Patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO) who underwent EVT were consecutively enrolled. Blood samples were collected in the emergency room and SII was calculated by neutrophils × platelets/lymphocytes. Participants were categorized into tertiles according to admission SII. The main outcome was defined as the occurrence of sICH, following the European Cooperative Acute Stroke Study III (ECASS-III) criteria. RESULTS: A total of 379 AIS-LVO patients with EVT were enrolled (median age = 71 years, 52.5% males). The median baseline National Institutes of Health Stroke Scale (NIHSS) score was 15 (IQR, 12-18). The median of SII was 820.9 × 109/L (IQR, 473.1-1345.2). Forty-three (11.3%) patients developed sICH. SII was found to be independently associated with sICH after EVT (adjusted odd ratio (OR) = 1.005 (per 10 units increase); 95% confidence interval (CI): 1.002-1.008; p = 0.002). Compared to patients in the lowest SII tertile, patients in the highest tertile had a higher risk of sICH (adj-OR 3.379; 95% CI 1.302-8.768; p = 0.012). The risk of sICH increased with the increase of SII in a dose-dependent manner (p for trend = 0.004). There was no interaction between potential modifiers and SII on sICH. CONCLUSION: Admission SII is positively associated with sICH in AIS-LVO patients treated with EVT. These results need to be confirmed in future studies.

Association of Blood Pressure Within 6 h After Endovascular Thrombectomy and Functional Outcomes in Ischemic Stroke Patients With Successful Recanalization.

Background and Purpose: Blood pressure in the days following endovascular thrombectomy (EVT) can influence functional outcomes of patients who have suffered an acute ischemic stroke, but whether the same is true of blood pressure during the first few hours after EVT is unclear. Methods: Several blood pressure parameters were retrospectively analyzed in acute ischemic stroke patients who underwent EVT at West China Hospital from March 2016 to December 2019. Baseline blood pressure, speed of blood pressure reduction, postoperative blood pressure, degree of blood pressure reduction, and quality of blood pressure management were evaluated during the first 24 h after EVT. We explored whether these parameters during different time windows correlated significantly with patients' modified Rankin Scale (mRS) score at 90 days. Results: Analysis of 163 patients showed that poor functional outcome (mRS scores 3-6) correlated significantly with higher postoperative blood pressure and worse blood pressure management during the first 6 h after EVT. Postoperative systolic blood pressure at 37 min after EVT was significantly higher in patients with poor outcome (141 mmHg) than in those with good outcome (mRS scores 0-2; 122 mmHg, p = 0.006), and systolic pressure >136 mmHg at this time point was associated with a significantly higher risk of poor outcome, before and after adjusting for other risk factors (adjusted OR 0.395, 95% CI 0.20-0.79). Conclusions: Among acute ischemic patients who successfully undergo recanalization, adequate blood pressure management during the first 30-40 min after EVT may be important for ensuring good 90-day functional outcomes.

Prognostic Significance of Admission Glucose Combined with Hemoglobin A1c in Acute Ischemic Stroke Patients with Reperfusion Therapy.

BACKGROUND: Elevated admission glucose and hemoglobin A1c (HbA1c) levels have been suggested to be associated with 90-day functional outcomes in acute ischemic stroke (AIS) patients with endovascular thrombectomy (EVT). However, whether the prognostic significance of admission glucose and that of HbA1c have a joint effect on patients with intravascular thrombolysis (IVT) and/or EVT remains unclear. This study aimed to explore the association between admission glucose combined with HbA1c and outcomes in patients with reperfusion therapy. METHODS: Consecutive AIS patients treated with IVT and/or EVT between 2 January 2018 and 27 February 2021 in West China hospital were enrolled. Admission glucose and HbA1c levels were measured at admission. Participants were divided into four groups according to admission glucose level (categorical variable: <7.8 and ≥7.8 mmol/L) and HbA1c level (categorical variable: <6.5% and ≥6.5%): normal glucose and normal HbA1c (NGNA), normal glucose and high HbA1c (NGHA), high glucose and normal HbA1c (HGNA), and high glucose and high HbA1c (HGHA). The primary outcome was an unfavorable functional outcome defined as a modified Rankin Scale (mRS) ≥ 3. The secondary outcome was all-cause mortality at 90 days. RESULTS: A total of 519 patients (mean age, 69.0 ± 13.4 years; 53.8% males) were included. Patients in the HGHA group had a significantly increased risk of unfavorable functional outcome (OR, 1.81; 95%CI, 1.01-3.23) and mortality (OR, 1.75; 95%CI, 1.01-3.06) at 90 days compared with those in the NGNA group after adjustment for confounders. There was no significant association between NGHA (OR, 0.43; 95%CI, 0.12-1.53) or HGNA (OR, 1.46; 95%CI, 0.84-2.56) and outcomes compared to the NGNA group. CONCLUSION: The combination of high admission glucose and high HbA1c level was significantly associated with unfavorable functional outcome and mortality at 90 days in AIS patients with reperfusion therapy.

Alterations of optic tract and retinal structure in patients after thalamic stroke.

Objectives: To investigate the association between degeneration of retinal structure and shrinkage of the optic tract in patients after thalamic stroke. Materials and methods: Patients with unilateral thalamic stroke were included. Structural magnetic resonance imaging (MRI) and optical coherence tomography (OCT) were performed to obtain parameters of optic tract shrinkage (lateral index) and retina structural thickness (retinal nerve fiber layer, RNFL; peripapillary retinal nerve fiber layer, pRNFL; ganglion cell-inner plexiform layer, GCIP), respectively. Visual acuity (VA) examination under illumination was conducted using Snellen charts and then converted to the logarithm of the minimum angle of resolution (LogMAR). We investigated the association between LI and OCT parameters and their relationships with VA. Results: A total of 33 patients and 23 age-sex matched stroke-free healthy controls were enrolled. Patients with thalamic stroke showed altered LI compared with control participants (P = 0.011) and a significantly increased value of LI in the subgroup of disease duration more than 6 months (P = 0.004). In these patients, LI were significantly associated with pRNFL thickness (ß = 0.349, 95% confidence interval [CI]: 0.134-0.564, P = 0.002) after adjusting for confounders (age, sex, hypertension, diabetes, dyslipidemia, and lesion volume). LI and pRNFL were both significantly associated with VA in all patients (LI: ß = -0.275, 95% CI: -0.539 to -0.011, P = 0.041; pRNFL: ß = -0.023, 95% CI: -0.046 to -0.001, P = 0.040) and in subgroup of disease duration more than 6 months (LI: ß = -0.290, 95% CI: -0.469 to -0.111, P = 0.002; pRNFL: ß = -0.041, 95% CI: -0.065 to -0.017, P = 0.003). Conclusion: Shrinkage of the optic tract can be detected in patients with thalamic stroke, especially after 6 months of stroke onset. In these patients, the extent of optic tract atrophy is associated with pRNFL thickness, and they are both related to visual acuity changes.

Association between neutrophil percentage-to-albumin ratio and 3-month functional outcome in acute ischemic stroke patients with reperfusion therapy.

Background: Neutrophils and albumin are associated with outcomes in patients with acute ischemic stroke (AIS). We aimed to explore the association between the neutrophil percentage-to-albumin ratio (NPAR), a novel marker of inflammation and oxidative stress, and the 3-month functional outcome in AIS patients with reperfusion therapy. Methods: This single-center, retrospective cohort study consecutively enrolled AIS patients with reperfusion therapy. Neutrophils and albumin were collected on admission. The primary outcome was a poor functional outcome, which was defined as a modified Rankin scale score of 3-6 at 3 months. Results: A total of 647 patients with AIS who received reperfusion therapy were analyzed. The mean age was 68.9 ± 13.9 years, and 358 (55.3%) of the patients were men. The median NPAR was 1.89 (interquartile range [IQR] 1.64-2.09). The percentage of patients with a 3-month poor functional outcome was 57.0% (369/647). NPAR was positively associated with a poor functional outcome (odds ratio [OR] 2.76, 95% CI: 1.52-5.03, p = 0.001). When patients were classified into tertiles, patients in the upper tertile (2.03-7.59) had a higher risk of poor outcome than patients in the lower tertile after adjusting for potential confounders (0.78-1.73) (OR 2.10, 95% CI: 1.28-3.42, p = 0.003). The risk of poor outcome increased with NPAR tertiles (p-trend = 0.003). The optimal cut-off value of the NPAR for predicting a poor outcome was 1.72, with a sensitivity of 0.75, and a specificity of 0.43. Conclusion: Neutrophil percentage-to-albumin ratio was significantly associated with 3-month poor functional outcomes in patients with AIS who received reperfusion therapy.

Relationships between cerebral small vessel diseases markers and cognitive performance in stroke-free patients with atrial fibrillation.

Background: Atrial fibrillation (AF) is related to an increased risk of cognitive dysfunction. Besides clinically overt stroke, AF can damage the brain via several pathophysiological mechanisms. We aimed to assess the potential mediating role of cerebral small vessel disease (SVD) and cognitive performance in individuals with AF. Methods: Stroke-free individuals with AF from the cardiological outpatient clinic at West China Hospital of Sichuan University were recruited. Extensive neuropsychological testing tools were assessed including global function, domains of attention, executive functions, learning, and memory. 3 T magnetic resonance imaging (MRI) was used for SVD markers assessment of white matter hyperintensities (WMH), lacunes, cerebral microbleeds (CMBs), and enlarged perivascular spaces (EPVS). The correlation between SVD markers and cognitive measures was analyzed by multivariate linear regression models. Results: We finally enrolled 158 participants, of whom 95 (60.1%) were males. In multivariate models, the presence of lacunes independently associated with Montreal Cognitive Assessment (Model 1: ß = 0.52, Model 2: ß = 0.55), Rey Auditory Verbal Learning Test-immediate and delayed recall (Model 1: ß = 0.49; ß = 0.69; Model 2: ß = 0.53; ß = 0.73) as well as Stroop-Acorrect (Model 1: ß = 0.12; Model 2: ß = 0.13), while total WMH severity independently associated with Strooptime-A (Model 1: ß = 0.24; Model 3: ß = 0.27), Strooptime-B (Model 1: ß = 0.17; Model 3: ß = 0.17), Strooptime-C (Model 1: ß = 0.22; Model 3: ß = 0.21) and Shape Trail Test-A (Model 1: ß = 0.17; Model 3: ß = 0.16). Conclusion: In our cohort of stroke-free individuals with AF, lacunes, and WMHs were independently associated with cognitive decline while EPVS and CMBs did not show significance. Assessment of SVD MRI markers might be valuable for cognition risk stratification and facilitate optimal management of patients with AF.

Prevalence difference of Helicobacter pylori infection between Tibetan and Han ethnics: The protocol of a meta-analysis on epidemiologic studies.

OBJECTIVES: Helicobacter pylori (Hp) is an identified carcinogenic pathogen of human gastric cancer. China is not only one of the countries with high incidence and mortality of gastric cancer, but also a high infection area of Hp. As a multi-ethnic country, China may have a diverse prevalence of Hp infection among ethnics. This meta-analysis tends to compare the prevalence of Hp infection between Tibetan and Han ethnics, the results may provide evidence for targeted screening and eradication of Hp in China. METHODS: The following databases will be searched: PubMed, Web of Science, Technology Periodical Database (VIP), China National Knowledge infrastructure (CNKI), and WanFang databases. Studies which reported the prevalence of Hp infection between Tibetans and Hans in China are eligible. Two reviewers will independently screen studies, extract data and assess the risk of bias of included studies. The prevalence of Hp infection between Tibetan and Han ethnics will be compared by meta-analysis. Heterogeneity tests and meta-analyses will be conducted using RevMan 5.3 and Stata 12.0 softwares. Meanwhile, subgroup analysis, publication bias and sensitivity analysis evaluation will be performed where applicable. RESULTS: This study will be reported in compliance with the PRISMA statement.This systematic review will not be submitted for any ethical approval since no privacy health information will be included. The findings will be published through peer-reviewed publications or conference presentations. PROSPERO REGISTRATION NUMBER: CRD42019121192. CONCLUSIONS: Our study will provide us evidence for tailored strategy and robustness of Hp screening and eradication among Tibetans.