IIH occurs worldwide. In the US, annual national incidence is estimated at 1.15 per 100,000.[3]Ghaffari-Rafi A, Mehdizadeh R, Ko AWK, et al. Idiopathic intracranial hypertension in the United States: demographic and socioeconomic disparities. Front Neurol. 2020 Sep 8;11:869.
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7506031
http://www.ncbi.nlm.nih.gov/pubmed/33013623?tool=bestpractice.com
IIH is most prevalent among obese women of childbearing age; the highest incidence in England is among females age 25 years (15.2 per 100,000).[4]Mollan SP, Aguiar M, Evison F, et al. The expanding burden of idiopathic intracranial hypertension. Eye (Lond). 2019 Mar;33(3):478-85.
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC6460708
http://www.ncbi.nlm.nih.gov/pubmed/30356129?tool=bestpractice.com
One study of IIH in Libya found an average incidence rate of 2.2 per 100,000 persons; among obese females ages 15 to 44 years, the rate rose to 21.4 per 100,000.[5]Radhakrishnan K, Thacker AK, Bohlaga NH, et al. Epidemiology of idiopathic intracranial hypertension: a prospective and case-control study. J Neurol Sci. 1993 May;116(1):18-28.
http://www.ncbi.nlm.nih.gov/pubmed/8509801?tool=bestpractice.com
In the US there is a higher incidence among black people (2.05 per 100,000) followed by white people (1.04 per 100,000), Hispanics (0.67 per 100,00), and Asian/Pacific Islanders (0.16 per 100,000).[3]Ghaffari-Rafi A, Mehdizadeh R, Ko AWK, et al. Idiopathic intracranial hypertension in the United States: demographic and socioeconomic disparities. Front Neurol. 2020 Sep 8;11:869.
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7506031
http://www.ncbi.nlm.nih.gov/pubmed/33013623?tool=bestpractice.com
The mean age at diagnosis is about 30 years.[6]Durcan FJ, Corbett JJ, Wall M. The incidence of pseudotumor cerebri: population studies in Iowa and Louisiana. Arch Neurol. 1988 Aug;45(8):875-7.
http://www.ncbi.nlm.nih.gov/pubmed/3395261?tool=bestpractice.com
The incidence of IIH has increased in recent years.[3]Ghaffari-Rafi A, Mehdizadeh R, Ko AWK, et al. Idiopathic intracranial hypertension in the United States: demographic and socioeconomic disparities. Front Neurol. 2020 Sep 8;11:869.
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7506031
http://www.ncbi.nlm.nih.gov/pubmed/33013623?tool=bestpractice.com
In England, the incidence of IIH rose between 2002 and 2016 from 2.3 to 4.7 per 100,000 persons.[4]Mollan SP, Aguiar M, Evison F, et al. The expanding burden of idiopathic intracranial hypertension. Eye (Lond). 2019 Mar;33(3):478-85.
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC6460708
http://www.ncbi.nlm.nih.gov/pubmed/30356129?tool=bestpractice.com
Increasing prevalence and incidence of IIH mirrors population increases in obesity and has been associated with social deprivation.[4]Mollan SP, Aguiar M, Evison F, et al. The expanding burden of idiopathic intracranial hypertension. Eye (Lond). 2019 Mar;33(3):478-85.
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC6460708
http://www.ncbi.nlm.nih.gov/pubmed/30356129?tool=bestpractice.com
[7]Miah L, Strafford H, Fonferko-Shadrach B, et al. Incidence, prevalence and healthcare outcomes in idiopathic intracranial hypertension: a population study. Neurology. 2021 Jan 20;96(8):e1251-61.
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC8055349
http://www.ncbi.nlm.nih.gov/pubmed/33472926?tool=bestpractice.com
Younger children with IIH are less likely to be obese than teenagers or adults.[8]Balcer LJ, Liu GT, Forman S, et al. Idiopathic intracranial hypertension: relation of age and obesity in children. Neurology. 1999 Mar 10;52(4):870-2.
http://www.ncbi.nlm.nih.gov/pubmed/10078746?tool=bestpractice.com
Incidence is the same in pregnant and nonpregnant women.[9]Sundholm A, Burkill S, Waldenlind E, et al. A national Swedish case-control study investigating incidence and factors associated with idiopathic intracranial hypertension. Cephalalgia. 2021 Dec;41(14):1427-36.
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC8619724
http://www.ncbi.nlm.nih.gov/pubmed/34407644?tool=bestpractice.com