A national Swedish case-control study investigating incidence and factors associated with idiopathic intracranial hypertension

Anna Sundholm,A Ingela M Nilsson Remahl,Sarah Burkill,Elisabet Waldenlind,Shahram Bahmanyar

doi:10.1177/03331024211024166

Abstract

ObjectiveTo study the incidence of idiopathic intracranial hypertension in Sweden and to explore whether previously proposed risk factors are associated with idiopathic intracranial hypertension by investigating the odds of exposure one year prior to diagnosis in patients compared to controls.MethodsUsing Swedish health care registers and validated diagnostic algorithms, idiopathic intracranial hypertension patients diagnosed between 2000–2016 were compared with randomly selected matched controls, five from the general population and five with obesity.ResultsWe identified 902 idiopathic intracranial hypertension patients and 4510 matched individuals in each control group. Mean incidence among inhabitants ≥18 years of age was 0.71 per 100,000; rising from 0.53 in 2000–2005 to 0.95 in 2012–2016. There were increased odds for idiopathic intracranial hypertension patients compared to general population for exposure to: kidney failure (odds ratio =13.2 (4.1–42.0)), arterial hypertension (odds ratio =17.5 (10.5–29.3)), systemic lupus erythematosus (odds ratio =13.8 (4.3–44.7)), tetracyclines, sulphonamides, lithium, and corticosteroids. In obese controls, odds ratios were also significantly increased for these exposures. Hormonal contraceptive use and exposure to pregnancy did not appear to be associated factors for idiopathic intracranial hypertension development.ConclusionsThe incidence of idiopathic intracranial hypertension in Sweden is lower relative to reports from other countries but is on the rise. This case-control study confirms several previously reported risk factors associated with idiopathic intracranial hypertension.

Highlights

Idiopathic intracranial hypertension (IIH) is a condition resulting in high intracranial pressure (ICP) without known cause
We found no association with hormonal contraceptive treatments, rather the opposite, i.e. the exposure to hormonal contraceptives was lower in IIH than in general population (GP) controls
Our study confirms that the incidence of IIH is rising in Sweden, with the largest increase in females of reproductive age

Summary

Introduction

Idiopathic intracranial hypertension (IIH) is a condition resulting in high intracranial pressure (ICP) without known cause. Other possible risk factors include Addisons disease, hyperparathyroidism, systemic lupus erythematosus (SLE), kidney failure, iron deficiency anaemia, and exposure to tetracyclines, sulphonamides, cycline antibiotics, vitamin A, lithium, hormonal contraceptives and pregnancy [4]. For some of these factors, the strength of the association has been questioned [4]. There are few previous case-control studies available with a representative control population investigating risk factors associated with IIH, most including between 20–60 cases [5,6,7,8,9] aside from two studies investigating fluoroquinolones antibiotics (339 cases) [10] and hormonal contraceptives (3323 cases) [11].

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