Literature ReviewEstimating the Global Incidence of Aneurysmal Subarachnoid Hemorrhage: A Systematic Review for Central Nervous System Vascular Lesions and Meta-Analysis of Ruptured Aneurysms
Introduction
Central nervous system vascular lesions (CNS-VLs)—such as aneurysms, arteriovenous malformations (AVMs), cavernous malformations (CMs), and other similar pathologies—can be some of the most challenging entities faced by neurosurgeons. Lesions presenting with hemorrhage often cause significant morbidity and mortality and require urgent neurosurgical intervention and neurocritical care to maximize the chances of a good recovery. Lesions found incidentally or presenting with signs and symptoms unrelated to hemorrhage, such as seizures or focal neurologic deficits, require careful consideration of the natural history versus the risk of treatment to determine whether intervention is warranted. Neurosurgeons are often the most experienced and educated in such treatments and decisions for CNS-VL.
Recently, there has been a growing acknowledgement that access to surgical care in underserved areas of the world should be more important in global health initiatives.1, 2 In particular, access to neurosurgical care is as limited as 1 per 10 million in large regions of the world.2, 3 A few studies have examined the incidence of CNS-VL in specific regional locations,4, 5 or focused on the global incidence of subarachnoid hemorrhage (SAH),6 or one type of CNS-VL such as unruptured intracranial aneurysms (UIAs).7 To our knowledge, no study has attempted to evaluate the worldwide epidemiology of CNS-VL to better define the disease incidence and, thus, the neurosurgical need to inform global health efforts. In this systematic review and meta-analysis, we aimed to evaluate the existing epidemiologic data, compile and analyze studies on the national and regional incidence of CNS-VL to estimate global volume, and define the disease burden to inform neurosurgical global health efforts. However, because of a lack of data in the existing literature, we could only estimate the incidence of aneurysmal subarachnoid hemorrhage (aSAH).
Section snippets
Systematic Review
The systematic review was done according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.8 Our primary objective was to estimate the global epidemiology of CNS-VL, including UIAs and aSAH, AVMs, CMs, dural arteriovenous fistulas (DAVFs), developmental venous anomalies (DVAs), and vein of Galen malformations located within the CNS.
The literature search was conducted via PubMed and Cochrane Databases in October 2016 and included sources between 1990 and
Systematic Review Results
The initial PubMed search yielded 1492 studies, and 366 were excluded because they were published before 1990 or were abstracts or involved animals only. By title and abstract review, 262 and 720 were excluded respectively, with 144 studies advancing for full-text review. Seventy-five studies were excluded on full-text review, leaving 69 included articles in addition to 28 studies from the review of references from both included and excluded full-texts, for a total of 97 included manuscripts.
Discussion
We estimated the global incidence of aSAH to be 6.67 per 100,000 persons. Based on this, we calculated that 490,155 (95% CI 330,689–679,650) suffer from aSAH each year. More than one half of these people live in low- and middle-income countries (Figure 7). There was wide regional variation in incidence rates with regard to aSAH (range, 0.71–12.38 per 100,000). Because of both the high incidence rate and it has the second largest population, the WPR has the greatest number of people affected by
Conclusions
As there is increasing interest about the role of neurosurgery in global health efforts, it is important to define disease burden. We found a lack of data regarding CNS-VL, particularly in AMR-L, AFR, EMR, and SEAR, and further study is needed to better define the incidence in these regions. We were able to provide an estimate for aSAH, which is one of the most common CNS-VLs health care providers encounter. Our model for aSAH estimated a global crude incidence of 6.67 per 100,000 persons
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Conflict of interest statement: The Vanderbilt Medical Scholar Program provided Abbas Rattani with support for this project.