Nationwide Prevalence and Geographic Variation of Idiopathic Intracranial Hypertension among Women in the United States

To determine the nationwide prevalence and geographic distribution of idiopathic intracranial hypertension (IIH) among women in the United States. Retrospective cross-sectional study using Medicaid claims and electronic health record data from the IRIS® Registry (Intelligent Research in Sight) and Sight Outcomes Research Collaborative (SOURCE). Female Medicaid beneficiaries 18 to 55 years of age with IIH diagnoses and prescriptions for acetazolamide or methazolamide in 2018 were identified, excluding those with other causes of intracranial hypertension. We calculated the proportion of women with IIH in the United States who were insured by Medicaid by combining analyses from the IRIS Registry and SOURCE. To calculate the number of women with IIH in each state, we divided the number of Medicaid beneficiaries by the proportion of patients insured by Medicaid. We used census data from the 2018 American Community Survey to calculate prevalence. We examined geographic variation in IIH prevalence using Moran's I statistic and compared it to obesity prevalence data from the 2018 Behavioral Risk Factor Surveillance System. In a validation study, we compared the calculated prevalence of IIH in Minnesota with similar data from the Rochester Epidemiology Project. Of 13 959 female Medicaid beneficiaries with IIH, 6828 had a prescription for acetazolamide or methazolamide. In the IRIS Registry and SOURCE, 25% of women with IIH were insured by Medicaid (95% confidence interval [CI], 16%–33%), suggesting that 27 312 women 18 to 55 years of age with IIH were taking acetazolamide or methazolamide in 2018 (6828 / 0.25 = 27 312). Prevalence was 3.44 per 10 000 women (95% CI, 2.61–5.39 per 10 000 women), and significant geographic variation was found (Moran I statistic, 0.20; P = 0.03), with higher prevalence in states where obesity was more common. The calculated prevalence of IIH in Minnesota was statistically equivalent to that identified using Rochester Epidemiology Project data (P < 0.05 for equivalence test). Idiopathic intracranial hypertension affects 3.44 per 10 000 women 18 to 55 years of age in the United States with significant geographic variation, some of which is explained by variation in obesity prevalence. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.