The exact incidence of subdural hematoma (SDH) is unknown. Acute SDH is found in about 11% to 20% of patients admitted to hospital with mild to severe traumatic brain injury.[4]Servadei F, Nasi MT, Giuliani G, et al. CT prognostic factors in acute subdural haematomas: the value of the 'worst' CT scan. Br J Neurosurg. 2000 Apr;14(2):110-6.
http://www.ncbi.nlm.nih.gov/pubmed/10889882?tool=bestpractice.com
The annual incidence of patients with closed head injury admitted to hospitals in the US is estimated at 200 per 100,000 people.[5]Narayan RK, Michel ME, Ansell B, et al. Clinical trials in head injury. J Neurotrauma. 2002 May;19(5):503-57.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1462953
http://www.ncbi.nlm.nih.gov/pubmed/12042091?tool=bestpractice.com
Overall, SDHs account for 50% to 60% of acute traumatic intracranial hematomas, and they are more likely to occur after falls or assaults than after motor vehicle accidents.[1]Zwienenberg-Lee M, Muizelaar JP. Clinical pathophysiology of traumatic brain injury. In: Winn HR, Youmans JR (eds): Youmans Neurological Surgery. Philadelphia, PA: WB Saunders; 2004:5039-64.[6]Fisher B, Thomas D, Peterson B. Hypertonic saline lowers raised intracranial pressure in children after head trauma. J Neurosurg Anesthesiol. 1992 Jan;4(1):4-10.
http://www.ncbi.nlm.nih.gov/pubmed/15815431?tool=bestpractice.com
[7]Marshall L, Gautille T, Klauber M. The outcome of severe closed head injury. J Neurosurg. 1991;75:S28-36. They can also occur with increased frequency in patients with coagulopathy (iatrogenic or pathologic).[1]Zwienenberg-Lee M, Muizelaar JP. Clinical pathophysiology of traumatic brain injury. In: Winn HR, Youmans JR (eds): Youmans Neurological Surgery. Philadelphia, PA: WB Saunders; 2004:5039-64.[8]Kawamata T, Takeshita M, Kubo O, et al. Management of intracranial hemorrhage associated with anticoagulant therapy. Surg Neurol. 1995 Nov;44(5):438-42;discussion 443.
http://www.ncbi.nlm.nih.gov/pubmed/8629228?tool=bestpractice.com
[9]Wintzen AR, de Jonge H, Loeliger EA, et al. The risk of intracerebral hemorrhage during oral anticoagulant treatment: a population study. Ann Neurol. 1984 Nov;16(5):553-8.
http://www.ncbi.nlm.nih.gov/pubmed/6508238?tool=bestpractice.com
Vitamin K antagonists increase the risk of SDH approximately threefold over the risk associated with factor Xa or antiplatelet agents and approximately twofold over the risk associated with direct thrombin inhibitors.[10]Connolly BJ, Pearce LA, Hart RG. Vitamin K antagonists and risk of subdural hematoma: meta-analysis of randomized clinical trials. Stroke. 2014 Jun;45(6):1672-8.
http://stroke.ahajournals.org/content/45/6/1672.long
http://www.ncbi.nlm.nih.gov/pubmed/24876259?tool=bestpractice.com
It is predicted that the incidence rates of chronic SDH in aging populations in the US Veterans Administration and civilian populations will reach 121.4 and 17.4 cases per 100,000 people, respectively, by 2030.[11]Balser D, Farooq S, Mehmood T, et al. Actual and projected incidence rates for chronic subdural hematomas in United States Veterans Administration and civilian populations. J Neurosurg. 2015 Nov;123(5):1209-15.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4575892
http://www.ncbi.nlm.nih.gov/pubmed/25794342?tool=bestpractice.com
Incidence estimates of chronic SDH in the UK range from 1.7 per 100,000 per year to 48 per 100,000 per year.[12]Stubbs DJ, Davies B, Hutchinson P, et al. Challenges and opportunities in the care of chronic subdural haematoma: perspectives from a multi-disciplinary working group on the need for change. Br J Neurosurg. 2022 Oct;36(5):600-8.
https://www.tandfonline.com/doi/full/10.1080/02688697.2021.2024508
http://www.ncbi.nlm.nih.gov/pubmed/35089847?tool=bestpractice.com
Several longitudinal studies have demonstrated increased incidence over time, likely driven by aging populations, increased detection linked to access to imaging, and use of anticoagulation.[12]Stubbs DJ, Davies B, Hutchinson P, et al. Challenges and opportunities in the care of chronic subdural haematoma: perspectives from a multi-disciplinary working group on the need for change. Br J Neurosurg. 2022 Oct;36(5):600-8.
https://www.tandfonline.com/doi/full/10.1080/02688697.2021.2024508
http://www.ncbi.nlm.nih.gov/pubmed/35089847?tool=bestpractice.com
Chronic SDHs occur most commonly in older people (age >65 years), and are frequently associated with a history of falls or anticoagulant use.[13]Baechli H, Nordmann A, Bucher HC, et al. Demographics and prevalent risk factors of chronic subdural haematoma: results of a large single-center cohort study. Neurosurg Rev. 2004 Oct;27(4):263-6.
http://www.ncbi.nlm.nih.gov/pubmed/15148652?tool=bestpractice.com
[14]Gaist D, García Rodríguez LA, Hellfritzsch M, et al. Association of antithrombotic drug use with subdural hematoma risk. JAMA. 2017 Feb 28;317(8):836-46.
https://jamanetwork.com/journals/jama/fullarticle/2605799
http://www.ncbi.nlm.nih.gov/pubmed/28245322?tool=bestpractice.com