IMPORTANCE: Subarachnoid hemorrhage (SAH) from ruptured intracranial aneurysms is a subset of stroke with high fatality and morbidity. Better understanding of a change in incidence over time and of ...factors associated with this change could facilitate primary prevention. OBJECTIVE: To assess worldwide SAH incidence according to region, age, sex, time period, blood pressure, and smoking prevalence. DATA SOURCES: We searched PubMed, Web of Science, and Embase for studies on SAH incidence published between January 1960 and March 2017. Worldwide blood pressure and smoking prevalence data were extracted from the Noncommunicable Disease Risk Factor and Global Burden of Disease data sets. STUDY SELECTION: Population-based studies with prospective designs representative of the entire study population according to predefined criteria. DATA EXTRACTION AND SYNTHESIS: Two reviewers independently extracted data according to PRISMA guidelines. Incidence of SAH was calculated per 100 000 person-years, and risk ratios (RRs) including 95% CIs were calculated with multivariable random-effects binomial regression. The association of SAH incidence with blood pressure and smoking prevalence was assessed with linear regression. MAIN OUTCOMES AND MEASURES: Incidence of SAH. RESULTS: A total of 75 studies from 32 countries were included. These studies comprised 8176 patients with SAH were studied over 67 746 051 person-years. Overall crude SAH incidence across all midyears was 7.9 (95% CI, 6.9-9.0) per 100 000 person-years; the RR for women was 1.3 (95% CI, 0.98-1.7). Compared with men aged 45 to 54 years, the RR in Japanese women older than 75 years was 2.5 (95% CI, 1.8-3.4) and in European women older than 75 years was 1.5 (95% CI, 0.9-2.5). Global SAH incidence declined from 10.2 (95% CI, 8.4-12.5) per 100 000 person-years in 1980 to 6.1 (95% CI, 4.9-7.5) in 2010 or by 1.7% (95% CI, 0.6-2.8) annually between 1955 and 2014. Incidence of SAH declined between 1980 and 2010 by 40.6% in Europe, 46.2% in Asia, and 14.0% in North America and increased by 59.1% in Japan. The global SAH incidence declined with every millimeter of mercury decrease in systolic blood pressure by 7.1% (95% CI, 5.8-8.4) and with every percentage decrease in smoking prevalence by 2.4% (95% CI, 1.6-3.3). CONCLUSIONS AND RELEVANCE: Worldwide SAH incidence and its decline show large regional differences and parallel the decrease in blood pressure and smoking prevalence. Understanding determinants for regional differences and further reducing blood pressure and smoking prevalence may yield a diminished SAH burden.
The pathogenesis of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage remains incompletely understood. It is generally assumed that it is caused by angiographic vasospasm. Our aim ...was to clarify the relationship among angiographic vasospasm, neurological worsening, cerebral infarction, and poor outcome and to investigate whether cerebral infarction also contributes to poor outcome by vasospasm-independent effects.
This exploratory analysis used data from 413 patients included in the Clazosentan to Overcome Neurological Ischemia and Infarction Occurring After Subarachnoid Hemorrhage (CONSCIOUS-1) trial. We studied the incidence of neurological worsening, cerebral infarction, and poor outcome in patients with and without angiographic vasospasm. Path analysis implemented by structural equation modeling was performed to determine direct and indirect path coefficients.
Of the 194 patients with moderate to severe vasospasm, 43% had neurological worsening of any cause, 20% had cerebral infarction, and 46% poor outcome. Path coefficients for direct effects on poor outcome were 0.20 for World Federation of Neurological Surgeons Grade 4 to 5, 0.13 for history of hypertension, 0.19 for angiographic vasospasm, 0.16 for neurological worsening, and 0.11 for new cerebral infarction. Cerebral infarction contributed to poor outcome by vasospasm-dependent and -independent effects.
Our data show that the majority of patients with moderate to severe angiographic vasospasm did not have neurological worsening of any cause or cerebral infarction. Besides, cerebral infarction also has a direct effect on outcome independent of angiographic vasospasm. This suggests that other coexisting factors might be involved in the pathogenesis of delayed cerebral ischemia, which should also be an important research target to improve outcome after subarachnoid hemorrhage.
BACKGROUND AND PURPOSE—Follow-up imaging is often performed in intracranial aneurysms that are not treated. We performed a systematic review and meta-analysis on patient- and aneurysm-specific risk ...factors for aneurysm growth.
METHODS—We searched EMBASE and MEDLINE for cohort studies describing risk factors for aneurysm growth. Two authors independently assessed study eligibility and rated quality with the Newcastle Ottawa Scale. With univariable Poisson regression analysis, we calculated risk ratios (RRs) with corresponding 95% confidence intervals (95% CI) of risk factors for aneurysm growth. Heterogeneity was assessed with I.
RESULTS—Eighteen studies on 15 patient-populations described 3990 patients with 4972 unruptured aneurysms. A total of 437 aneurysms (9%) enlarged during 13 987 aneurysm-years of follow-up. Compared with aneurysms ≤4 mm, RRs were 2.56 (95% CI, 1.93–3.39; I=98%) for ≥5 mm, 2.80 (95% CI, 2.01–3.90; I=96%) for ≥7 mm, and 5.38 (95% CI, 3.76–7.70; I=97%) for ≥10 mm. Compared with aneurysms on the middle cerebral artery, the RR for basilar artery was 1.94 (95% CI, 1.32–2.83; I=57%). RRs were 2.03 (95% CI, 1.52–2.71; I=59%) for smoking at baseline, 2.04 (95% CI, 1.56–2.66; I=90%) for multiple unruptured aneurysms, 1.26 (95% CI, 0.97–1.62; I=59%) for women, 1.24 (95% CI, 0.98–1.58; I=40%) for hypertension, and 2.32 (95% CI, 1.46–3.68; I=91%) for irregular aneurysm shape. Compared with other regions, RR was 0.75 (95% CI, 0.58–0.96) for Japan and 0.64 (95% CI, 0.45–0.90) for Finland.
CONCLUSIONS—Most risk factors for aneurysm growth are consistent with risk factors for rupture. In contrast with rupture, the risk of growth was smaller in Japanese and Finnish cohorts compared with other regions. Pooling of individual patient data from low- and high-risk geographical regions is needed to assess independent predictors of aneurysm growth.
IMPORTANCE: The risk of procedural clinical complications and the case-fatality rate (CFR) from preventive treatment of unruptured intracranial aneurysms varies between studies and may depend on ...treatment modality and risk factors. OBJECTIVE: To assess current procedural clinical 30-day complications and the CFR from endovascular treatment (EVT) and neurosurgical treatment (NST) of unruptured intracranial aneurysms and risk factors of clinical complications. DATA SOURCES: We searched PubMed, Excerpta Medica Database, and the Cochrane Database for studies published between January 1, 2011, and January 1, 2017. STUDY SELECTION: Studies reporting on clinical complications, the CFR, and risk factors, including 50 patients or more undergoing EVT or NST for saccular unruptured intracranial aneurysms after January 1, 2000, were eligible. DATA EXTRACTION AND SYNTHESIS: Per treatment modality, we analyzed clinical complication risk and the CFR with mixed-effects logistic regression models for dichotomous data. For studies reporting data on complication risk factors, we obtained risk ratios (RRs) or odds ratios (ORs) with 95% CIs and pooled risk estimates with weighted random-effects models. MAIN OUTCOMES AND MEASURES: Clinical complications within 30 days and the CFR. RESULTS: We included 114 studies (106 433 patients with 108 263 aneurysms). For EVT (74 studies), the pooled clinical complication risk was 4.96% (95% CI, 4.00%-6.12%), and the CFR was 0.30% (95% CI, 0.20%-0.40%). Factors associated with complications from EVT were female sex (pooled OR, 1.06 95% CI, 1.01-1.11), diabetes (OR, 1.81 95% CI, 1.05-3.13), hyperlipidemia (OR, 1.76 95% CI, 1.3-2.37), cardiac comorbidity (OR, 2.27 95% CI, 1.53-3.37), wide aneurysm neck (>4 mm or dome-to-neck ratio >1.5; OR, 1.71 95% CI, 1.38-2.11), posterior circulation aneurysm (OR, 1.42 95% CI, 1.15-1.74), stent-assisted coiling (OR, 1.82 95% CI, 1.16-2.85), and stenting (OR, 3.43 95% CI, 1.45-8.09). For NST (54 studies), the pooled complication risk was 8.34% (95% CI, 6.25%-11.10%) and the CFR was 0.10% (95% CI, 0.00%-0.20%). Factors associated with complications from NST were age (OR per year increase, 1.02 95% CI, 1.01-1.02), female sex (OR, 0.43 95% CI, 0.32-0.85), coagulopathy (OR, 2.14 95% CI, 1.13-4.06), use of anticoagulation (OR, 6.36 95% CI, 2.55-15.85), smoking (OR, 1.95 95% CI, 1.36-2.79), hypertension (OR, 1.45 95% CI, 1.03-2.03), diabetes (OR, 2.38 95% CI, 1.54-3.67), congestive heart failure (OR, 2.71 95% CI, 1.57-4.69), posterior aneurysm location (OR, 7.25 95% CI, 3.70-14.20), and aneurysm calcification (OR, 2.89 95% CI, 1.35-6.18). CONCLUSIONS AND RELEVANCE: This study identifies risk factors for procedural complications. Large data sets with individual patient data are needed to develop and validate prediction scores for absolute complication risks and CFRs from EVT and NST modalities.
BACKGROUND AND PURPOSE—Prediction of the risk of rupture of unruptured intracranial aneurysms is mainly based on aneurysm size and location. Previous studies identified features of aneurysm shape and ...flow angles as additional risk factors for aneurysm rupture, but these studies were at risk for confounding by patient-specific risk factors such as hypertension and age. In this study, we avoided this risk by comparing characteristics of ruptured and unruptured aneurysms in patients with both aneurysmal subarachnoid hemorrhage and multiple intracranial aneurysms.
METHODS—We included patients with aneurysmal subarachnoid hemorrhage and multiple aneurysms who presented to our hospital between 2003 and 2013. We identified the ruptured aneurysm based on bleeding pattern on head computed tomography or surgical findings. Aneurysm characteristics (size, location, shape, aspect ratio neck-to-dome length / neck-width, flow angles, sidewall or bifurcation type, and contact with bone) were evaluated on computed tomographic angiograms. We calculated odds ratios with 95% confidence intervals with conditional univariable logistic regression analysis. Analyses were repeated after adjustment for aneurysm size and location.
RESULTS—The largest aneurysm had not ruptured in 36 (29%) of the 124 included patients with 302 aneurysms. Odds ratios for aspect ratio ≥1.3 was 3.3 (95% confidence intervals 1.3–8.4) and odds ratios for irregular shape was 3.0 (95% confidence intervals 1.0–8.8), both after adjustment for aneurysm size and location.
CONCLUSIONS—Aspect ratio ≥1.3 and irregular shape are associated with aneurysm rupture independent of aneurysm size and location, and independent of patient characteristics. Additional studies need to assess to what extent these factors increase the risks of rupture of small aneurysms in absolute terms.
Patients with aneurysmal subarachnoid hemorrhage (SAH) who experience delayed cerebral ischemia (DCI) have an increased risk of poor outcome. Delayed cerebral ischemia is considered to be caused by ...vasospasm. However, not all patients with DCI have vasospasm. Inversely, not all patients with vasospasm develop clinical symptoms and signs of DCI. In the past, treatments aiming at vasospasm were not successful in preventing ischemia. The purpose of this review is to give an overview of clinical data showing that DCI cannot always be attributed to vasospasm, and to present an in-depth analysis of clinical and autopsy studies on the role of microthrombosis in the pathogenesis of DCI. Clinical studies show that DCI is associated with an activation of the coagulation cascade within a few days after SAH, preceding the time window during which vasospasm occurs. Furthermore, impaired fibrinolytic activity, and inflammatory and endothelium-related processes, lead to the formation of microthrombi, which ultimately result in DCI. The presence of microthrombi is confirmed by autopsy studies. Insight in the pathophysiology of DCI is crucial for the development of effective therapies against this complication. Because multiple pathways are involved, future research should focus on drugs with pleiotropic effects.
As it is often assumed that delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) is caused by vasospasm, clinical trials often focus on prevention of vasospasm with the aim to improve ...clinical outcome. However, the role of vasospasm in the pathogenesis of DCI and clinical outcome is possibly smaller than previously assumed. We performed a systematic review and meta-analysis on all randomized, double-blind, placebo-controlled trials that studied the effect of pharmaceutical preventive strategies on vasospasm, DCI, and clinical outcome in SAH patients to further investigate the relationship between vasospasm and clinical outcome. Effect sizes were expressed in pooled risk ratio (RR) estimates with corresponding 95% confidence intervals (CI). A total of 14 studies randomizing 4,235 patients were included. Despite a reduction of vasospasm (RR 0.80 (95% CI 0.70 to 0.92)), no statistically significant effect on poor outcome was observed (RR 0.93 (95% CI 0.85 to 1.03)). The variety of DCI definitions did not justify pooling the DCI data. We conclude that pharmaceutical treatments have significantly decreased the incidence of vasospasm, but not of poor clinical outcome. This dissociation between vasospasm and clinical outcome could result from methodological problems, sample size, insensitivity of clinical outcome measures, or from mechanisms other than vasospasm that also contribute to poor outcome.
Subarachnoid hemorrhage (SAH) is an acute cerebrovascular event which can have devastating effects on the central nervous system as well as a profound impact on several other organs. SAH patients are ...routinely admitted to an intensive care unit and are cared for by a multidisciplinary team. A lack of high quality data has led to numerous approaches to management and limited guidance on choosing among them. Existing guidelines emphasize risk factors, prevention, natural history, and prevention of rebleeding, but provide limited discussion of the complex critical care issues involved in the care of SAH patients. The Neurocritical Care Society organized an international, multidisciplinary consensus conference on the critical care management of SAH to address this need. Experts from neurocritical care, neurosurgery, neurology, interventional neuroradiology, and neuroanesthesiology from Europe and North America were recruited based on their publications and expertise. A jury of four experienced neurointensivists was selected for their experience in clinical investigations and development of practice guidelines. Recommendations were developed based on literature review using the GRADE system, discussion integrating the literature with the collective experience of the participants and critical review by an impartial jury. Recommendations were developed using the GRADE system. Emphasis was placed on the principle that recommendations should be based not only on the quality of the data but also tradeoffs and translation into practice. Strong consideration was given to providing guidance and recommendations for all issues faced in the daily management of SAH patients, even in the absence of high quality data.
In clinical trials and observational studies there is considerable inconsistency in the use of definitions to describe delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage. A ...major cause for this inconsistency is the combining of radiographic evidence of vasospasm with clinical features of cerebral ischemia, although multiple factors may contribute to DCI. The second issue is the variability and overlap of terms used to describe each phenomenon. This makes comparisons among studies difficult.
An international ad hoc panel of experts involved in subarachnoid hemorrhage research developed and proposed a definition of DCI to be used as an outcome measure in clinical trials and observational studies. We used a consensus-building approach.
It is proposed that in observational studies and clinical trials aiming to investigate strategies to prevent DCI, the 2 main outcome measures should be: (1) cerebral infarction identified on CT or MRI or proven at autopsy, after exclusion of procedure-related infarctions; and (2) functional outcome. Secondary outcome measure should be clinical deterioration caused by DCI, after exclusion of other potential causes of clinical deterioration. Vasospasm on angiography or transcranial Doppler can also be used as an outcome measure to investigate proof of concept but should be interpreted in conjunction with DCI or functional outcome.
The proposed measures reflect the most relevant morphological and clinical features of DCI without regard to pathogenesis to be used as an outcome measure in clinical trials and observational studies.
IMPORTANCE: Unruptured intracranial aneurysms not undergoing preventive endovascular or neurosurgical treatment are often monitored radiologically to detect aneurysm growth, which is associated with ...an increase in risk of rupture. However, the absolute risk of aneurysm rupture after detection of growth remains unclear. OBJECTIVE: To determine the absolute risk of rupture of an aneurysm after detection of growth during follow-up and to develop a prediction model for rupture. DESIGN, SETTING, AND PARTICIPANTS: Individual patient data were obtained from 15 international cohorts. Patients 18 years and older who had follow-up imaging for at least 1 untreated unruptured intracranial aneurysm with growth detected at follow-up imaging and with 1 day or longer of follow-up after growth were included. Fusiform or arteriovenous malformation-related aneurysms were excluded. Of the 5166 eligible patients who had follow-up imaging for intracranial aneurysms, 4827 were excluded because no aneurysm growth was detected, and 27 were excluded because they had less than 1 day follow-up after detection of growth. EXPOSURES: All included aneurysms had growth, defined as 1 mm or greater increase in 1 direction at follow-up imaging. MAIN OUTCOMES AND MEASURES: The primary outcome was aneurysm rupture. The absolute risk of rupture was measured with the Kaplan-Meier estimate at 3 time points (6 months, 1 year, and 2 years) after initial growth. Cox proportional hazards regression was used to identify predictors of rupture after growth detection. RESULTS: A total of 312 patients were included (223 71% were women; mean SD age, 61 12 years) with 329 aneurysms with growth. During 864 aneurysm-years of follow-up, 25 (7.6%) of these aneurysms ruptured. The absolute risk of rupture after growth was 2.9% (95% CI, 0.9-4.9) at 6 months, 4.3% (95% CI, 1.9-6.7) at 1 year, and 6.0% (95% CI, 2.9-9.1) at 2 years. In multivariable analyses, predictors of rupture were size (7 mm or larger hazard ratio, 3.1; 95% CI, 1.4-7.2), shape (irregular hazard ratio, 2.9; 95% CI, 1.3-6.5), and site (middle cerebral artery hazard ratio, 3.6; 95% CI, 0.8-16.3; anterior cerebral artery, posterior communicating artery, or posterior circulation hazard ratio, 2.8; 95% CI, 0.6-13.0). In the triple-S (size, site, shape) prediction model, the 1-year risk of rupture ranged from 2.1% to 10.6%. CONCLUSION AND RELEVANCE: Within 1 year after growth detection, rupture occurred in approximately 1 of 25 aneurysms. The triple-S risk prediction model can be used to estimate absolute risk of rupture for the initial period after detection of growth.
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