Given the relatively low incidence, high prehospital death rate, substantial geographical differences, and complex disease origin (combination of genetic and environmental risk factors), epidemiologic research on subarachnoid hemorrhage (SAH) and its risk factors is challenging. In practice, we are more or less forced to exploit compromised study designs and nonrepresentative data in such circumstances where it is almost impossible to gather comprehensive data through an optimal design. For example, hospital-based patient cohorts, administrative data repositories, and short-term population-based studies from small geographical regions are often used to research the incidence, case fatality, and risk factors of SAH, regardless of their inherent and self-evident limitations. Since studies on the epidemiology of SAH focus largely on identifying possible risk factors that could aid in disease diagnostics, treatment, and prevention, we aimed to review recent evidence on modifiable risk factors for SAH. In this context, we also try to explain the methodological reasons behind some of the conflicting results and to discuss the primary strengths and limitations of different study designs used in the field of SAH epidemiology. Based on our findings, smoking, high blood pressure, and possibly low physical activity are the only risk factors with high-quality evidence supporting their causal role in SAH. In addition, since all 3 commonly used study designs in SAH epidemiology, namely, hospital-based, population-based, and administrative register-based studies, have their own strengths and limitations, the most robust risk factor estimates and other epidemiologic measures of SAH can likely be established by combining various overlapping and high-quality sources of information in the future.

中文翻译：

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蛛网膜下腔出血的可改变危险因素：叙述性回顾，重点是常见的争议和流行病学陷阱。


鉴于发病率相对较低、院前死亡率高、地理差异大以及疾病起源复杂 （遗传和环境风险因素的结合），蛛网膜下腔出血 （SAH） 及其风险因素的流行病学研究具有挑战性。在实践中，在几乎不可能通过优化设计收集全面数据的情况下，我们或多或少被迫利用受损的研究设计和不具代表性的数据。例如，基于医院的患者队列、管理数据存储库和来自较小地理区域的基于人群的短期研究通常用于研究 SAH 的发病率、病死率和危险因素，无论其固有的和不言而喻的局限性如何。由于 SAH 流行病学研究主要集中在确定可能有助于疾病诊断、治疗和预防的可能危险因素，因此我们旨在回顾有关 SAH 可改变危险因素的最新证据。在这种情况下，我们还试图解释一些相互矛盾的结果背后的方法学原因，并讨论 SAH 流行病学领域中使用的不同研究设计的主要优势和局限性。根据我们的研究结果，吸烟、高血压和可能的低体力活动是唯一有高质量证据支持它们在 SAH 中的因果作用的危险因素。 此外，由于 SAH 流行病学中所有 3 种常用的研究设计，即基于医院、基于人群和基于行政登记的研究，都有自己的优势和局限性，因此未来可能会通过结合各种重叠和高质量的信息来源来建立最稳健的 SAH 风险因素估计和其他流行病学指标。