Global prevalence and incidence of chronic subdural hematoma: A systematic review.

Introduction: Chronic subdural hematoma (cSDH) is one of the most common conditions in neurosurgery. However, its epidemiology remains poorly investigated. Research question: To systematically evaluate all available evidence on the global prevalence and incidence of cSDH from 1970 to 2022. Methods: A systematic review according to PRISMA guidelines using PubMed, Cochrane, and EMBASE was conducted on articles from 1970 to 2022. Studies reporting regional-to-national incidence or prevalence were included. Studies were graded based on quality of evidence. Results: 6253 articles were identified, 18 meeting inclusion criteria. Seven articles reported surgical incidence and 11 provided incidence based on imaging or clinical findings. Six additional articles were evaluated for demographic data. No study discussing prevalence was found. 18 reported incidence from 12 countries in five continents. The lowest incidence was found in Brazil (3.39/100,000/year), and the highest in the USA at 39.1/100,000. Incidence increases with age and may be up to three times higher among patients over 80. It also appears to increase over time, probably with improved diagnostics. In most studies, incidence was higher in men. The most common aetiology was trauma and falls. Other contributing factors were chronic alcohol abuse, anticoagulation, and violence. Several articles did not report any cause. Discussions and conclusions: Epidemiological data remain sparse, with limited incidence data and no prevalence data. The level of evidence remains medium to low with regional differences in methodology, suggesting the need for standardisation. Incidence has increased over time in all regions, particularly amongst older patients. This trend will likely continue with an ageing population.